Seismic parameters re-determined from historical seismograms of 1935-Erdek-Marmara Island and 1963-Çinarcik Earthquakes

Abstract

In this study, the original seismograms of the 1935-Erdek-Marmara Island and 1963-Çinarcik Earthquakes, recorded at local and regional distances, were vectorized. The epicentral locations have been calculated using available readings from original records and also ISS and seismic station bulletins for 04.01.1935-14:41 and 16:20 Marmara Island-Erdek Earthquakes and 18.09.1963-16:58 Çinarcik Earthquake. The epicenter determinations show that the first event in 04.01.1935 was located at 40.72N-27.72E, while the second one occurred at 40.61N-27.43E, indicating that both were located near the Marmara Island. Another finding is that the 1963 event was located at 40.80N-29.18E, near the Princes' Island fault. Furthermore, moment tensor inversion method was applied on these earthquakes by using original seismograms, which provided an opportunity to illuminate the seismotectonic features of Marmara Region based on the retrieved fault mechanism solutions. For the first time, the fault mechanisms for 04.01.1935-14:41 and 16:20 Earthquakes were determined using moment tensor inversion from the original seismic waveforms. Likewise, the result obtained for the fault mechanism of 1963 Çinarcik Earthquake showed normal fault mechanism with much shallower depth than estimated before. Our preferred solutions showed that the fault mechanisms for the three events are normal faults and coincide with the seismotectonic structure of the Marmara Region.

Baarr Batrk et al. Earth, Planets and Space (2016) 68:158 DOI 10.1186/s40623-016-0528-8

Seismic parameters re-determined fromhistorical seismograms of1935-Erdek Marmara Island and1963-narck Earthquakes

Nilay Baarr Batrk1*, Nurcan Meral zel1 and Marco Caciagli2

Introduction

The North Anatolian fault (NAF) system across the Turkey is a right lateral strike-slip fault about 1500km from Karlova triple junction to the Sea of Marmara. It plays an important geodynamic role between Anatolian and Eurasia plates by moving with an average slip rate at 2030mm/year (McKenzie 1972; McClusky etal. 2000; Barka 1992; Fichtner etal. 2013; Dresen etal. 2007). The western part of NAF system enters the Sea of Marmara in the Gulf of Izmit and then splits into two distinct branches that dene, tectonically, northern and southern boundaries of the Marmara region. The complex tec-tonic structure of NAF system was responsible for many destructive earthquakes in the past (Ambraseys and

Jackson 2000), and the recent seismic activity showed an apparently westward propagating sequence of earthquakes since 1939 (Barka 1996; Hubert-Ferrari etal. 2000; Parsons etal. 2000; Stein etal. 1997; Toksz etal. 1979; Reilinger etal. 2000), leaving a long segment within Marmara Sea near Istanbul as a seismic gap (Le Pichon etal. 2001; Oglesby etal. 2008). On the western part of northern branch of the North Anatolian fault, two strike-slip faults are connected with a fault zone consisting of three basins (narck, Central and Tekirda) in the Marmara Sea. The faults ruptured after 1912 Ganos and 1999 zmit earthquakes (Le Pichon etal. 2003; Armijo etal. 2002). Also, a pull-apart structure accompanying with normal faulting components seems to control narck and Central basins (Armijo etal. 2005). Some active faults in the Marmara basin were also historically tsunamigenic (Altinok and Ersoy 2000; Altinok etal. 2011; Ambraseys 2002; Armijo etal. 2005; Hancilar 2012; Ozel etal. 2011; Ozcicek etal. 19661967).

*Correspondence: [email protected]; [email protected]

1 Geophysics Department, Kandilli Observatory and Earthquake Research Institute, Boazii University, 34684 Cengelkoy, Uskudar, Istanbul, Turkey

Full list of author information is available at the end of the article

2016 The Author(s). This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/

Web End =http://creativecommons.org/licenses/by/4.0/ ), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

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The knowledge of the historical earthquakes which occurred in the Marmara Region indicates that stanbul has been aected by high intensity (Io=VIIIIX) events for the interval of 250300 years (e.g., 1509, 1766)

(Ambraseys 2002, 2009; Guidoboni et al. 1994; Duman etal. 2016). This available evidence and the existing seismic gap suggest the idea that the destructive earthquake probability in this city is above 65 % in 30 years (Ozel etal. 2011; Parsons 2004; Parsons etal. 2000). Undoubtedly, the high level of seismic hazard poses a major threat to the lives of one-third of total Turkish population (13 millions of inhabitant only in Istanbul) around this city (Altinok etal. 2011; Hancilar 2012; Hubert-Ferrari etal. 2000; Kalkan etal. 2009; Ozel etal. 2011; Parsons 2004; Parsons etal. 2000). Since the earthquake cycle has long period of time, examining historical events can give new insights about the seismotectonics of their respective region (Kanamori 1988). Although the historical earthquakes are so important to the understanding of the seismic characteristics of a region, our knowledge about these earthquakes is very limited, except dening them by macroseismic, paleoseismologic and geological data. In that respect, analyzing historical earthquakes using their original seismograms which were recorded instrumentally comes into prominence which will enable seismologists to expand their knowledge about the seismicity of long period of time of a region (Kanamori 1988; Lee etal. 1988; Batll etal. 2008). However, this process entails much eort because of the deciencies in technology of the historical recording systems. Usually the information necessary for all the process of the analyzing of these records, such as instrument constants and time accuracy, is missing or doubtful (Batll etal. 2008; Kanamori 1988; Abe 1994). The importance of studying

historical earthquakes by analyzing original records through the modern techniques has been realized by many researchers over the world (e.g., Baskoutas et al. 2000; Dineva etal. 2002; Kanamori etal. 2010; Lee etal. 1988; Pino etal. 2000, 2008; Schlupp 1996; Schlupp and Cisternas 2007; Stich etal. 2003, 2005; Teves-Costa etal.

1999; Cadek 1987; Abe 1994; Rivera etal. 2002; Kikuchi etal. 2003), which presented dierent methods and stimulated to carry out more comprehensive investigations about historical earthquakes over the world.

To date, collection and distribution of these early records necessitated too much eort. In recent years, there has been increasing interest in historical seismo-grams and many initiatives around the world have been intended to create digital forms of the early seismograms and their related material to preserve seismological heritage of the world such as International Data Centre (IDC), World Wide Seismographic Stations Network (WWSSN), and International Association of Seismology and Physics of the Earths Interior (IASPEI) (Michelini et al. 2005; Batll et al. 2008). More recently, SISMOS (Michelini etal. 2005) and EUROSEISMOS (Ferrari and Pino 2003; Ferrari and Roversi Monaco 2005) projects undertook the scanning, archiving and distribution of historical seismograms. KOERI also have taken part of this project which enabled us to obtain old records analyzed in this study to understand the seismological properties of the 1935 and 1963 Earthquakes that occurred in the Marmara Region.

The seismic hazard analysis of Marmara Region is also related to the evaluation of historical earthquakes, especially those which are believed to have taken place in the Sea of Marmara (Ambraseys 2002; Ambraseys and Finkel 1991) (Fig. 1). Understanding seismological properties

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of the instrumentally recorded 1935 ErdekMarmara Island and 1963 narck Earthquakes to understand the seismotectonics of the Marmara Region has also great importance in this assessment. Particularly, the ambiguity of the locations, magnitudes and fault mechanisms of these earthquakes inspired us to study the 1935 and 1963 historical events. Illuminating whether these earthquakes are related to the so-called faults, on the northern branches of the western continuation of the NAF system (Le Pichon et al. 2001), may also contribute to the knowledge of the seismotectonic structure of the region. Several studies had been published on the 1935 and 1963 Earthquakes (e.g., Ambraseys and Finkel 1987; Ambraseys 1988; ziek 1996; Taymaz etal. 1991; Toksz etal. 1979); however, many of these studies were based on only geological and macroseismic data, which may not be as accurate as found by an assessment using instrumental earthquake records.

In this study, the historical 1935 ErdekMarmara Islands Ms = 6.4 and 1963 narck Ms = 6.3 Earthquakes were investigated using P and S waveform data at regional seismic stations. To carry out this process, the seismic traces recorded on the analog seismograms were obtained in digital form through the vectorization method. The seismic traces acquired in digital form were corrected geometrically to avoid the distortions caused by the needle mechanisms of old-time seismic instruments. In addition, the epicenters of the 1935 ErdekMarmara Islands Ms=6.4 and the 1963 narck

Ms = 6.3 Earthquakes were re-determined using the arrival times obtained from ISS Bulletins as well as the P and S readings based on original seismograms through the HYPOCENTRE 3.2. by Lienert (1994). Fault plane solutions were also obtained for the 1935 ErdekMarmara Islands M=6.4 and 1963 narck Ms=6.3 Earthquakes using the moment tensor inversion time-domain moment tensor inversion (TDMT-INV) algorithm produced by Dreger (2002).

04.01.1935, ErdekMarmara Island Earthquakes

On 04.01.1935, three successive events occurred in Erdek and Marmara Islands (Figs.2, 3; Pinar and Lahn 1952). The rst shock (Ms=6.4) was reported to have occurred at 14:41:29 (GMT) and located at 40.64N, 27.51E, with an intensity Io=IX (MSK) assigned by Ambraseys (1988).

The damage caused 5 death and 30 injured. This event was followed by 15:18:57 (GMT) (Ms = 4.6), 15:19:24 (GMT) (Ms = 4.5) Earthquakes. Shortly after these events, there has been another shock which took place at 16:20:05 (GMT) (Ms = 6.3) (Ambraseys and Jackson 2000) and was strongly felt in a large area. The aftershocks were monitored through the recording systems of that period for 3months. (Pinar and Lahn 1952). The

depths of these two earthquakes that occurred at 14:41:29 and 16:20:05 were reported as 20 and 30km, respectively, by Ayhan etal. (1981). Table1 shows the epicentral locations given by dierent sources for 04.01.1935-14:41 and 16:20 (GMT) Earthquakes. It should be noted the large ambiguity of the location.

Although a seismological study based on original seismic waveforms was not carried out for these two earthquakes that occurred on 04.01.1935, the focal mechanism

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Table 1 Epicentral locations given in various sources mostly based onthe macroseismic investigations, forthe 04.01.1935-14:41 and16:20 (GMT) Earthquakes

Date andtime Latitude Longitude Depth Ms References

04.01.1935-14:41 (GMT)

40.64N 27.51E 6.4 1

40.50N 27.60E 6.4 240.0N 27.5E 340.40N 27.49E 30 6.4 4

04.01.1935-16:20 (GMT)

40.55N 27.75E 6.3 2

40.0N 27.5E 340.30N 27.45E 20 6.3 4

1 Ambraseys (1988), 2 Ambraseys and Jackson (2000), 3 ISS Bulletin, 4 Kalafat etal. (2007)

for the fault concerned has been proposed as 100/40/90 (strike/dip/rake) by Nalbant etal. (1998) who investigated the Coulomb stress change after these shocks. There are some reports that this earthquake caused tsunami, and its eects were published in some newspapers. One of them is the Kurun newspaper on January 10, 1935, reporting the words of an eyewitness, named Mr. Kevork, of the earthquake. He claimed that when the third shock came, which occurred 45min after the rst shock, he was able to see the sea, which was not normally visible in his position, which may imply an evidence of seismic seawave, as stated by Altnok and Alpar (2006).

18.09.1963,narck Earthquake

The narck Earthquake which occurred on 18.09.1963at 16:58 GMT was located in the western Marmara, with a magnitude of Ms=6.3 (Fig.4). It was reported by Ozcicek (19661967) that after the earthquake, the seashells were noticed on the coastline of the Mudanya Bay in the east west direction. Kuran and Yalciner (1993) stated that the sea waves reached about 1 m height along the shore in some region, which may be the evidence that the earthquake is tsunamigenic. Ergin etal. (1967) reported that 4 buildings were destroyed and 2 buildings were damaged and the damage was observed mostly in narck. There were also reports of damage in Yalova. In total, 7 buildings were demolished in Yalova and narck Regions. This earthquake caused 1 dead (Ergin, et al. 1967). The locations and the mechanism solutions estimated before are signicantly scattered. Dierent epicentral locations and fault mechanism solutions for 18.09.1963-16:58 (GMT) Earthquake are given in Table2.

Epicenter estimations

It is a well-known fact that, before the 1960s, for seismological observatories in many places including Mediterranean countries, the quality of input data containing the arrival times is not sufficient for an accurate epicentral location procedure, and the biggest problem is the accuracy of the ISS epicenters, especially before 1960 (Ambraseys and Melville 1982). This fact inspired us to analyze the epicenter of these signicant events that occurred in the Marmara Region by assessing the available P and S arrival times using modern approximation.

In order to re-determine the epicenters of the 1935 and 1963 events, we used P and S arrival times based on original seismograms, original bulletins to cross-check the data reported by International Seismological Summary (ISS) Bulletins. We also checked the dierence between the theoretical phase readings from travel time tables for ISS Bulletin and also especially the original records which are not in the list of available readings. It has been possible to see the reliability of a station time by comparing the phases with the theoretical arrival times to see whether there are large clock bias, misidentication of the seismic phases, or typing mistakes and so on. We also compared the available seismic stations bulletins with the ISS Bulletin data.

Epicentral location was performed using the program HYPOCENTRE 3.2. (Lienert 1994) and the velocity model of Kalafat etal. (1987). The estimated results are shown in Table3 and Fig.5. We also used the IASPEI91 velocity model (Kennett and Engdahl 1991) to check the reliability

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Table 2 Earthquake parameters givenby dierent sources for18.09.1963-16:58 (GMT) Earthquake

Date andtime Latitude Longitude Depth (km) M Strike Dip Rake References

18.09.1963-16:58 (GMT) 40.83N 29.01E 140.80N 29.13E 240.77N 29.12E 6.3 (Ms) 340.90N 29.20E 15 2 5.2 (Mb) 304 56 82 4

40.60N 29.00E 268 70 125 5

40.70N 28.95E 6.4 (Ms) 640.90N 29.20E 33 6.4 (Ms), 5.2 (Mb) 152 40 32 7, 9

40.90N 29.20E 33 5.2 (Mb) 118 20 8

1 Ozcicek (19661967), 2 ISS Bulletin for 1963, 3 Alsan etal. (1976), 4 Taymaz etal. (1991), 5 Jackson and McKenzie (1988), 6 Ambraseys and Jackson (2000), 7 Jackson and McKenzie (1984), 8 McKenzie (1972), 9 Kalafatet al.(2009)

Table 3 Location Results ofthe 04.01.1935, 14:41, 16:20 and18.09.1963, 16:58 Earthquakes

Earthquake Result VM1 RMS value

Error inlatitude (km)

Error inlongitude (km)

Result VM2 RMS value

Error inlatitude (km)

Error inlongitude (km)

04.01.1935, 14:41 40.72N27.72E 2.47 8 8 40.69N27.71E 2.49 8 904.01.1935, 16:20 40.61N27.43E 3.44 13 13 40.62N27.43E 3.45 14 1318.09.1963, 16:58 40.80N29.18E 2.82 10 11 40.80N29.15E 2.83 10 11

VM1 velocity model estimated by Kalafat etal. (1987), VM2 global IASPEI91 velocity model

of the results, but the results did not change signicantly, which do not exceed 3km for both events that occurred on 04.01.1935, and 1km for the 18.09.1963Earthquake. The rst earthquake that occured in 1935 (at 14:41) has condence limits of 8km in longitude and latitude, which denes the epicenter quality. The second event in 1935 (at 16:20) shows errors about 13km in longitude and latitude. 18.09.1963 Earthquake has errors of about 11km in

longitude and 10km in latitude. Although errors in longitude and latitude seem to be large for these events, it is possible to observe the large condence limits for the historical earthquakes, also in the published papers such as Kanamori etal. (2010), Batll etal. (2008, 2010) and Tobin and Sykes (1968). The data obtained from the ISS Bulletin for this earthquake indicated large errors during the process of epicentral location. For this reason, we followed

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the process of removing the arrival time readings that show time residuals above 100s. However, the total RMS value was still too large after the rst run. Then, the readings with time residuals larger than 10s were removed to obtain smaller total RMS value.

For 04.01.1935-14:41 event, in addition to data from ISS Bulletin, the readings from obtained original records which are not in the list of ISS Bulletin and are seismograms of ISK, ATH, MNH, FBR, COI stations were included. The readings of P and S arrival times from the seismograms of ZUR, STR, PRA, JENA, DBN, COP, BER, ZAG, VIE, PCN stations, which are also available in the ISS Bulletin, were reevaluated. The same procedure was followed also for 04.01.1935-16:20 ErdekMarmara Island Earthquake. The readings of P and S arrival times obtained from ISS Bulletins indicated large errors for 04.01.1935-14:41 as in the case of rst event. The readings based on available original records enabled to compare P and S arrival times with ISS Bulletin and reduce large residuals. As a result, the RMS values were obtained as 2.47 and 3.44 for 04.01.1935-14:41 and 16:20 Earthquakes, respectively.

For 18.09.1963-16:58 narck Earthquake, the readings based on original seismograms were also available in the list of ISS Bulletins. Therefore, we included these readings in our epicenter solution. Most of the readings for P and S waves based on original records agree with the readings of ISS Bulletins. During the process of epicenter location of the historical earthquakes interest of this study, P and S arrival times in original seismograms were also checked and the large residuals were reduced. The RMS value was acquired as 2.82 for this event. In most cases, our readings for P and S wave agree with the readings of ISS Bulletins. Theoretical arrival times (Additional le1: Appendix C; Table C1, C2 and C3) were calculated for the velocity model used to compare with the phase reading data. By doing this comparison, the inconsistencies may be recognized in the data of the phases, such as large clock bias, misidentication of the seismic phases or typing mistakes.

We have azimuthal gap in station coverage 139 for 04.01.1935, 14:41 Earthquake, while the azimuthal gap is 87 for the second event of 04.01.1935. For 18.09.1963, 16:58 Earthquake, the azimuthal gap is 38. These azimuthal gap values are sufficient to constrain location accuracy for these events as the largest azimuthal gap is, at worst, 180 as also specied by several authors such as Engdahl etal. (1998, 2007). Furthermore, global bulletins such as those reported by the International Seismologcal Center and the US Geological Survey National Earthquake Information Center (NEIC) that contain predominantly teleseismic arrival time data have an accuracy of 1015 km when the largest azimuthal gap

is < 200 in continental regions, reported by Sweeney (1996) and Zare etal. (2004).

Vectorization andcorrection procedure ofhistorical seismograms

The historical seismograms used in this study were obtained from the SISMOS seismogram archive in the framework of the EUROSEISMOS Project. European countries were scanned at a resolution of 1016 dpi using very high-quality scanners at the SEISMOS laboratories of the Istituto Nazionale di Geosica e Vulcanologia in Rome (Michelini etal. 2005; Pintore etal. 2005; Ferrari and Pino 2003; Batll et al. 2008). In order to use historical seismograms, the raster images of the interested recorded waveform must be converted into vector format with a vectorization procedure. However, it may not be possible to use all the scanned paper seismograms due to the poor quality of the recorded signal and seismograms without recorded earthquakes.

In this study, we obtained 81 seismograms from 23 seismic stations for the 04.01.1935 14:41:29 and 16:20:05 Earthquakes that occurred at Marmara IslandErdek and 38 seismograms from 11 stations for 18.09.1963-16:58 narck-Yalova Earthquake. During the analysis of the analog records, we realized that earthquakes of our interest were not registered on some seismograms. Also, it was not possible for some records to be vectorized due to the poor quality of recorded waveforms on paper seismograms. Consequently, we have vectorized 35 seismograms from 16 stations for 04.01.1935 14:41:29, 33 seismograms from 15 stations for 04.01.1935-16:20:05 Erdek Earthquake, and 29 seismograms from 10 stations for 18.09.1963-16:58:08 narck Earthquake. Figure 6 shows the station locations of obtained seismograms for 04.01.1935-14:41 and 16:20 Marmara IslandErdek Earthquakes and 18.09.1963-16:58 narck-Yalova Earthquake.

In this study, manual vectorization method that is based on redrawing seismic traces on old record by using the mouse pointer has been used to convert seismic traces recorded on paper to a digital time series. Vectorization process is of considerable eort due to many problems that arise from quality of trace on the paper and the mechanism of traditional seismometers. Examples are pen slipping on the paper and little oscillations that are interpreted as noise on the trace because of instrumentation (Batll etal. 2008; Kanamori etal. 2010). Correct identication of the earthquake to be studied can also be troublesome, which necessitates counting very carefully time marks available on records. Yet, some of the historical records do not have well-marked time marks, and therefore it is essential to obtain some bulletins for stations and regard delay times of the rst arrival times in

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relation to station distances. Besides, the needle mechanism leads to curvatures of the traces. Inadequate contrast between recorded waveform and the background poses a serious problem during the digitization of the historical seismograms, which may be seen in the case of mechanical recording when the paper was insufficiently smoked (Batll etal. 1997, 2008, 2010; Kanamori etal. 2010). In this study, we have also encountered some problems that complicate the vectorization process. For example, we observed seismic traces in mesh on historical records (Additional le 1: Figure F1). Since the historical records were exposed to many external factors, it is possible to encounter records including erased parts of traces, which is also another problem that makes difcult to vectorize old seismograms when a part of trace is erased on the paper. If the missing part is small, the erased part can be completed; however, they do not provide a reliable basis when large parts are missing from the records as it seems in Additional le1: Figure F2 which shows the historical seismogram recorded at KAS (Kastamonu, Turkey) station for the 1963 Earthquake.

After obtaining vectorized scanned seismic traces, it is necessary to carry out some corrections, such as the geometry of the recording system, deconvolution with the instrument response, etc. One of the major problems with the historical seismograms is the curvatures on vectorized seismic traces, which is the result of the mechanism of needle mounted on a nite-length pivoting arm of mechanical seismometer. In such a case, the abscissa of the seismogram cannot be obtained as linear function of time (Grabrovec and Allegretti 1994). In this study, the

geometrical distortions such as the pen curvature, uneven paper speed and skew on seismic traces have been corrected by applying the formula of Grabrovec and Allegretti (1994) and Samardjieva etal. (1998).

In that respect, it is necessary to nd some parameters for the geometrical corrections as the arm length of the mechanical recording system. In cases where the proper seismic traces could not be obtained after correction process, we tried dierent solutions to nd especially the arm length value of the recording systems of the seismograms. For example, we observed a big problem for the records of ISK (Kandilli) station. Since it has been possible for us to obtain the arm length values by measuring directly from instruments available at ISK (Kandilli) station, we used these values to remove circular arcs on original seismograms for the 1935 Earthquake. This eort considerably changed the seismic traces on the records from its rst solutions with wrong arm length value (Fig.7). The arm length value of the Wiechert ISK (Kandilli) station seismometer was measured as 150mm, while the value of the arm length of Mainka seismometer was measured as

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450mm. Despite the fact that we obtained more proper seismograms to analyze, there were still problems with the records of ISK station. Probably, this situation arises from the traces that are very close to each other, which also requires a considerable eort during vectorization process. Another example of the curvature correction of the seismogram recorded by Tromometrograph Omori instrument at PRT (Italy) station for the 1935 Earthquake can be seen in Additional le1: Figure F3.

The vectorized points of seismic signal recorded on original seismogram were scaled to time (X) and amplitude (Y) axes considering the length between two time marks on the original records to obtain equal time intervals on time (X) axis. In order to acquire equally spaced points on the time axis, a polynomial interpolation method has been used. Interpolated data have been sampled using 0.1s sampling rate.

The instrument response correction

In order to carry out instrument response correction, the seismic traces have been corrected by specifying transfer function with the free period of pendulum (To), damping constant (h) and the magnication (V) of the instrument for mechanical sensors (Herak etal. 1998). In fact, it is sometimes possible to nd these values on the original seismograms even though it is a low possibility. However, in general, it is a difficult task to obtain the collection of the instrument constants which are essential to perform the process, for the old seismic recording systems since the necessary documents are not available. For this purpose, a special eort has been made to gather every possible source. These sources include Uccle (UCC), Prague (PRA), Fabra (FBR), DeBilt (DBN), Copenhagen (COP) seismic station bulletins for the year 1935 and Timisoara (TIM) seismic station bulletin for the year 1963, Bulletin of National Research Council in McComb and West (1931) and INGV (http://storing.ingv.it/es_web/Data/Es_map.html

Web End =http://storing.ingv.it/es_web/Data/ http://storing.ingv.it/es_web/Data/Es_map.html

Web End =Es_map.html , EUROSEISMOS Project). Also, some European observatories (SPC, BRA) have been consulted for the documentation and bulletins of the stations (see Additional le1: Appendix D; Table D1, D2). Here, it is important to note that the instrument constants given in the Bulletin of the National Research Council cannot be considered of the same value of the station bulletins. We used these values only in the case that we could not obtain the instrument constants from the seismic station bulletins.

Moment tensor inversion

For the moment tensor inversion, three component seismograms of DBN, ZAG, JENA, COP stations for the 1935 Earthquakes and BRA, COP, DBN, PAV, ROM for the 1963 Earthquake were selected. We tried to nd

more seismograms for this process. We used the locations that we previously obtained for these events to perform this application (Figs.2, 3, 4). However, as pointed out by many researchers (Kanamori 1988; Lee etal. 1988; Batll et al. 2008; Stich et al. 2005), studied on analyzing historical records, it is a big deal to nd adequate and high-quality old seismograms for the seismological process and to provide much better azimuthal coverage. We had to exclude seismograms from other stations for this analysis since most of them do not have all the three components (usually they have one component), which does not allow us to rotate seismogram components into the cylindrical or spherical coordinate system, which is essential for this process. Vectorized and geometrically corrected seismic traces were converted to SAC format in order to perform the essential operations such as ltering, rotating and integration. TDMT-INV algorithm produced by Dreger (2002) was used to moment tensor inversion. The synthetic data were generated using an algorithm named FKRPROG (Saikia 1994), which calculates the Greens functions in the frequency domain. The Greens functions were modeled using the velocity model estimated by Kalafat etal. (1987). The procedure of the coherency between the synthetic and observed waveform is assessed with variance reduction (VR). Here, the objective is the correlation between these synthetic waveforms and the waveforms produced with the earthquake source. In Eq. (1), datai represents the observed waveforms, whereas the synthi indicates the synthetic waveforms (Dreger 2002). The non-DC component, compensated-linear-vector-dipole (CLVD) component, is also depicted in Figs.8, 9and 10

1

datai

synthi

R =

i

2

100.

(1)

data2i

We used 0.0250.075-Hz lter for the both events (14:41:30 and 16:20:05) that occurred on 04.01.1935 and 0.0350.085-Hz lter for the 18.09.1963 event. For this process, the instrumental correction was performed by multiplying the amplitudes with a coefficient to approximate to synthetic waveforms. These coefficients (Additional le 1: Appendix E) were determined by trying dierent values by approximating these values to the magnitudes of these events which were previously reported (Tables1, 2).

In the application of moment tensor inversion, we encountered the common problems also cited by Stich etal. (2005) such as the absence of three components of the historical seismograms, uneven time marks on the records (which results in an incoherency between seismic

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waveforms when they are superposed to each other). For two earthquakes, the seismograms were obtained from the eastern part of the epicenter, which is a trouble for estimating earthquake fault mechanism. The process of cutting three components from the starting time is troublesome due to the fact that the starting times of the waveforms are usually doubtful on the original seismograms. Radial and transversal components must be obtained by rotating the NSEW components.

The comparison of the moment tensor solutions for 04.01.1935-14:41 and 16:20 Erdek Earthquakes is given in Fig.11: (1) the result of this study found for the 14:41

Earthquake 140/56/98 (strike/dip/rake); (2) the result found for the 16:20 Earthquake 352/51/77 (strike/

dip/rake); (3) the fault mechanism for 04.01.1935-14:41 Earthquake given by Nalbant etal. (1998) as 100/40/90 (strike/dip/rake). However, it must be reminded that this solution is a preference for modeling this event by examining Coulomb stress changes, not based on the analyzing original records. We believe that we obtained best coherency of the observed and synthetic waveforms (Figs. 12, 13). The moment tensor inversion solutions of this study for fault mechanisms of these two events

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may contribute to the seismotectonic of the Marmara Region, since no study was carried out using original seismograms. In addition, this rigorous eort contains valuable importance as it claries for the rst time the fault characteristics of the couple of 1935 Earthquakes. Also, a reasonable consistency between observed and synthetic waveforms was achieved using moment tensor inversion application (Fig. 14) for the 18.09.1963 16:58 narck Earthquake. We can also see a comparison of the moment tensor solutions for this event in Fig. 15, which seems below.

Discussion

The seismic parameters and fault mechanism solutions were obtained for 04.01.1935-14:41 and 16:20 Earthquakes through the modern seismological techniques

central location determined by Ambraseys (1988). The second large shock that occurred at 16:20 was located 40.61N27.43E, which is situated at about 27 km NW of the epicentral location (40.55N27.75E) determined by Ambraseys and Jackson (2000). Semi-major axes are <30km for the error ellipses for both earthquakes that occurred in 1935 (at 14:41 and 16:20) (Fig.5). The condence limits obtained for these events may seem relatively large compared to those found for some recent earthquakes as in Pierri et al. (2013), which is probably the result of the poor arrival time data of historical earthquakes as pointed out by Kanamori etal. (2010). However, the condence errors may be obtained with semi-major axis reaching to the values at least 50 km reported by Okal etal. (2012) and Kanamori etal. (2010) for the historical events and also for more recent earthquakes given by Schweitzer and Kennett (2007) and Henry and Das (2002). A thorough re-assessment of the

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fault mechanism of these earthquakes was one of the objectives of this work since the information of fault characteristics is not available. We investigated the fault characteristics of these two earthquakes, which were not determined previously by analyzing of original seismo-grams. Nalbant et al. (1998) modeled these two earthquakes as resulted from one rupture for investigating Coulomb stress changes. The appropriate focal mechanism assumption when modeling these earthquakes was

chosen as 100/40/90 (strike/dip/rake). In our study, the fault characteristics of these two earthquakes have been determined for the rst time using modern seismological analysis. We found fault characteristics for these two shocks by applying moment tensor inversion on the waveforms obtained by vectorizing on the original records. Comparing the observed and synthetic waveforms, the coherency between them may present reliable solutions.

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Our preferred moment tensor solution for the rst shock that occurred in 1935 indicates predominantly normal faulting at 4 km depth. The nodal planes have orientations of 140/56/98 (strike/dip/rake) and 335/34.8/77.23. As a non-double-couple component, the compensated linear dipole vector (CLVD) of the moment tensor inversion is 4.1, which indicates the smallest CLVD value of the all solutions for this earthquake. Inversion produces a total seismic moment of Mo = 4.112 1025 dyn cm (Mw = 6.4). The hypocentral depth with the best t is 4 km, which indicates that the focus of this earthquake was closer to the surface than previously reported as 20 km by Ayhan et al. (1981). Moment tensor inversion solutions for the second large shock, which occurred at 16:20, gave the Nodal Plane 1, 2 as 352/51/77 and 153/40/105 (strike/dip/

rake). Seismic moment is Mo=1.321025dyncm. We choose the fault plane solution for the second event as 352/51/77 at a depth of 10km which is much shallower than previous estimate of 40km (Ayhan etal. 1981). Also, it can be seen that the faulting type changes from normal to reverse fault type in deeper parts (1420km) for the rst event, and the variance reduction (VR) does not change so much with these dierent fault mechanisms at dierent depths, but the CLVD of the chosen solution with respect to depth is much smaller than other (Figs.8, 16). For the second event, the mechanism changes from normal to reverse at the depth 12km (Figs.9, 17). However, the largest VR value is obtained at the depth of 10km. Also, it should also be noted that VR is not the one aspect that we take into consideration to assess the fault mechanism solutions. One can obtain smaller VR by using more stations with a good azimuthal coverage (Ylmazer 2009), which was one of the problems for us to obtain more seismograms during the process of this study and it may be the result of the variation of mechanisms at some depths. Although the acquired fault mechanism solutions are given by the high degree of sensitivity with respect to the depth with a little change of variance reduction values, normal faulting type of the solutions at the shallower depths found in this study corresponds to the tectonic structure of the Marmara region. Also, the preferences for the solutions of the two possible planes (fault plane and auxiliary plane) were made by the tec-tonic properties and the knowledge of this region. Some studies show the existence of the normal faulting system in this area such as Parke etal. (1999, 2002) who mentions the basins that are half graben, formed on north dipping fault planes, in the southern Sea of Marmara by using regional grid of high-resolution seismic reection proles. They also reported that there is most likely a zone of deformation on the north of Marmara Island. In addition, normal faults dip both north and south bound the deep basins in the Sea of Marmara, which may be interpreted as the uplift of the Islands including

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the Marmara, Imral and Princes Island (Taymaz et al. 1991). Some recent studies also report that normal faults observed at a shallow level in the sediment are not deeply rooted (Zitter et al. 2012). In the southern part of the Eastern Ganos Oshore cluster, on the surroundings Marmara Island (especially north, northwest and western parts of the island) which was investigated in detail by Korkusuz (2012) and Korkusuz ztrk etal. (2015), has extensional fault plane solutions resultswhich backs up the fault mechanism of two events of 1935 that indicated NWSE normal faulting type.

Other nding related to these two earthquakes occurred in 1935 is that they are two separate events. We realized the waveforms are not similar to each other in terms of their shape by comparing available original seismograms. This can be seen dominantly on the original seismograms of ISK station. Their nearly equal magnitude and the proximity of occurring time are also indications that the second shock at 16:20 is not the aftershock of the rst shock at 14:41.

It can be seen that both events (14:41 and 16:20) in 1935 were located in the vicinity of the Marmara Islands which are northward continuations of Kapidag Peninsula in geological and geomorphological aspect (Altnok and Alpar 2006). It was also reported by Papazachos and Papazachhou (1997) that there has been a similar historical earthquake that occurred in Marmara Island on 11.08.1265. The magnitude and epicenter of this event are given as M=6.6 and 40.7N, 27.4E, respectively (Papazachos and Papazachhou 1997). The locations of these historical and instrumental earthquakes are not on the main fault zone (Fig.1) and on the extending southern branch of NAF (Altnok and Alpar 2006).

The location of the 1963 Yalova Earthquake is a signi-cant question since the rupture of this event and western termination of the 1999 Izmit Earthquake are debated (Muller etal. 2006). In this study, epicenter of the 1963 narck Earthquake is found to be at 40.80N29.18E,

based on the readings on the original seismograms and ISC Bulletin data, in the Sea of Marmara. The semi-major axis of the error ellipse for the 1963 Earthquake is about 10km (Fig.5), which is relatively small compared to two events relocated in this study. Our result is closer to the epicenter location (40.80N29.13E) of ISS Bulletin data for the year 1963. The epicenter location found by Taymaz etal. (1991) is 15km northeast of the fault of Princes Island and 25km northeast of the narck Fault pointed out by Muller etal. (2006) (Fig.4). The epicenter location result determined by this study is 11km southwest of the location found by Taymaz etal. (1991) and is closer to the Princes Island Fault and the margin of the narck Basin. Another study by Bulut and Aktar (2007) using seismological method for this event creates an uncertainty, especially in the epicenter location. They re-determined the location of the 1963 event using ISC Bulletin data that includes the stations within a 12 distance and found that this event occurred on the north of the Armutlu Peninsula. In that study, they also compared two waveform pairs including mainshocks and aftershocks of 1963 narck Earthquake and 1999 zmit Earthquake, which suggested that the similarity of rst motion polarity of the compared waveforms may be interpreted as the same fault mechanism of aftershocks of two earthquakes.

The preferred result for 18.09.1963-16:58 narck Earthquake from moment tensor inversion applications is a fault mechanism with 285/59/101 (strike/

dip/rake) at 12km. The other nodal plane is obtained as 126/32/71 (strike/dip/rake). A total seismic moment of

Mo=2.041025dyncm (Mw=6.2) is found. Taymaz etal. (1991) determined fault characteristics of the 1963 event using P and SH waveforms and rst motion polarities of P waves. They found almost pure normal slip on south and north dipping nodal planes with 304/56/82 (strike/dip/rake). Our preferred solution (285/59/101)

is close to the solution, NE-dipping, pure normal fault which was thought to have ruptured to NE margin of the

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narck Basin (Fig. 1), found by Taymaz et al. (1991). Also, NE-dipping plane of our solution is a little steeper and has more easterly strike than their result. As already mentioned, the pull-apart mechanism in the Marmara Sea is thought to have formed the basin structures in this region. The solutions obtained are normal faulting mechanisms with changing the strike that rotates to some degree at the depths 22 and 24km. Looking at Figs.10 and 18, the variance reduction values seem to have close values to each other at the dierent depths. We preferred the solution 285/59/101 (strike/dip/rake) at 12km, consistent with the stress tensor alignments of the Northern narck Basin (Korkusuz ztrk etal. 2015), by indicating WNWESE-trending normal faults as the solution reported by Taymaz et al. (1991). Despite the fact that there are researches implying that narck basin exhibits compressional (Pinar etal. 2009) and strike-slip motions (zalaybey etal. 2002), recent studies indicate that there are normal and oblique structures in the narck area from the analyses of the focal mechanism applications (Karabulut etal. 2002, 2011; Tun etal. 2011; rgl and Aktar 2001). In a very recent study, the present stress state in the Marmara Region was investigated by Korkusuz ztrk et al. (2015) who analyzed the fault plane solutions with a comprehensive and high-quality data of small earthquakes, nding the normal components in the area that correspond to our fault mechanism solutions. The study demonstrated that normal and oblique faulting system dominates in narck Basin and Yalova cluster, which matches with the pull-apart mechanism suggested by Armijo etal. (2005). Also, deep basins, resulting of the normal faults, in the Marmara Sea (Taymaz etal. 1991) may also back up this mechanism in the region.

Conclusion

To conclude, the seismic parameters of three large historical earthquakes, 04.01.1935 (GMT) 14:41 and 16:20 (GMT) Marmara IslandErdek and 18.09.1963-16:58

(GMT) narck-Yalova Earthquakes, which occurred in the Marmara Region, have been assessed using original records from mechanical and also electromagnetic (Galitzin 1914) seismographs. The epicenter estimations gave the results 40.72N27.72E and 40.61N27.43E for the 04.01.1935-14:41 (GMT) and 16:20 (GMT) Earthquakes, respectively. Furthermore, 18.09.1963-16:58 (GMT) Earthquake was located at 40.80N29.18E. Despite the fact that we had some decits in the seismogram quality and limited azimuthal coverage, the fault mechanisms for these events that occurred in 1935 were determined for the rst time. Our preferred solution showed that the fault mechanisms for the three events are normal faults and coincide with the seismotectonic structure of the Marmara Region, considering the recent studies (Korkusuz ztrk et al. 2015; Karabulut etal. 2002, 2011; Tun etal. 2011; rgl and Aktar 2001). These ndings may be developed by analyzing also other historical earthquakes in the Marmara Region and attribute to understanding of its complicated seismotectonic structure and seismic hazard analysis.

Additional le

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References

Abe K (1994) Instrumental magnitudes of historical earthquakes by 1892 to

1898. Bull Seismol Soc Am 84:415425Ambraseys NN, Finkel C (1987) The SarosMarmara earthquake of 9 August

1912. Earthq Eng Struct Dyn 15:189211Ambraseys NN (2009) Earthquakes in the Mediterranean and Middle East: a multidisciplinary study of seismicity up to 1900. Cambridge University Press, Imperial College, London, ISBN 978 0 521 87292 8Ambraseys NN (1988) Engineering seismology. Earthq Eng Struct Dyn

17:1105Ambraseys NN, Finkel C (1991) Long-term seismicity of Istanbul and of the

Marmara Sea region. Terra Nova 3(5):527539Ambraseys NN, Jackson JA (2000) Seismicity of Sea of Marmara (Turkey) since

1500. Geophys J Int 141:F1F6Ambraseys NN (2002) The seismic activity of the Marmara Sea region over the last 2000 years. Bull Seismol Soc Am 92:118Ambraseys NN, Melville CP (eds) (1982) A history of Persian earthquakes.

Cambridge University Press, CambridgeAlsan E, Tezuan L, Bath M (1976) An earthquake catalogue For Turkey for the interval 19131970. Tectonophysics 31:T13T19Altnok Y, Alpar B (2006) Marmara Island earthquakes, of 1265 and 1935; Turkey.

Nat Hazards Earth Syst Sci 6:9991006Altinok Y, Ersoy S (2000) Tsunamis observed on and near the Turkish coast. Nat

Hazards 21:185205Altinok Y, Alpar B, Ozer N, Aykurt H (2011) Revision of the tsunami catalogue aecting Turkish coasts and surrounding regions. Nat Hazards 11:273291Armijo R, Meyer B, Navarro S, King G, Barka A (2002) Asymmetric slip portioning in the Sea of Marmara pull-apart: a clue to propagation process of the North Anatolian fault? Terra Nova 14:8086Armijo R, Pondard N, Meyer B, Uarku G, De Lpinay BM, Malavieille J,

Dominguez S, Gustcher MA, Schmidt S, Beck C, aatay N, akr Z, mren C, Eri K, Natalin B, zalaybey S, Tolun L, Lefvre I, Seeber L, Gasperini L, Rangin C, Emre , Sarkavak K (2005) Submarine fault scarps in the Sea of Marmara pull-apart (North Anatolian fault): implications for seismic hazard in Istanbul. Geochem Geophys Geosyst 6:Q06009. doi:http://dx.doi.org/10.1029/2004GC000896

Web End =1 http://dx.doi.org/10.1029/2004GC000896

Web End =0.1029/2004GC000896 Ayhan A, Alsan E, Sancakl N, er SB (1981) Trkiye ve Dolaylar Deprem

Katalou 18811980. Boazii niv, stanbulBarka A (1992) The North Anatolian fault zone. Ann Tecton 6:164195

Barka A (1996) Slip distribution along the North Anatolian fault associated with the large earthquakes of the period 1939 to 1967. Bull Seismol Soc Am 86:12381254

Batll J, Susagna T, Roca A (1997) A processing system for old records of regional earthquakes: analysis of the 19th November 1923 earthquake in the Pyrenees. Cah Cent Eur Godyn Sismol 13:149157

Batll J, Stich D, Maci R (2008) Quantitative analysis of early seismograph recordings. Mod Approaches Solid Earth Sci 2(IV):385402. doi:http://dx.doi.org/10.1007/978-1-4020-8222-1_19

Web End =10.1007/978-1-4020-8222-1_19

Batll J, Stich D, Maci R, Morales J (2010) Moment tensor inversion for the 5 July 1930 Montilla Earthquake (Southern Spain). Seismol Res Lett 82(5):725731Baskoutas IG, Kalogeras IS, Kourouzidis M, Panopoulou G (2000) A modern technique for the retrieval and processing of historical seismograms in Greece. Nat Hazards 21:5564Bulut F, Aktar M (2007) Accurate relocation of zmit Earthquake (Mw = 7.4,

1999) aftershocks in narck basin using double dierence method. Geophys Res Lett 34:L10307Cadek O (1987) Studying earthquake ground motion in Prague from Wiechert seismograph records. Gerl Beitr Geophys 96:438447Dineva S, Batll J, Mihailov D, van Eek T (2002) Source parameters of four strong earthquakes in Bulgaria and Portugal at the beginning of the 20th century. J Seismol 6:99123Dreger DS (2002) Time-domain moment tensor inverse code (TDMT_INVC) version 1.1. Available via DIALOG. ftp://www.orfeus-eu.org/pub/software/iaspei2003/8511_tutorial.pdf

Web End =ftp://www.orfeus-eu.org/pub/soft ftp://www.orfeus-eu.org/pub/software/iaspei2003/8511_tutorial.pdf

Web End =ware/iaspei2003/8511_tutorial.pdf Dresen G, Bonho M, Aktar M, Eyidoan H (2007) Drilling the North Anatolian

Fault. Sci Drill Spec Iss 1:4244. doi:http://dx.doi.org/10.2204/iodpsds01172007

Web End =10.2204/iodpsds01172007 Duman TY, an T, Emre , Kadirolu FT, Baarr Batrk N, Kl T, Arslan

S, zalp S, Kartal RF, Kalafat D, Karakaya F, Erolu Azak T, zel NM, Ergintav S, Akkar S, Altnok Y, Tekin S, Cingz A, Kurt A (2016)

Seismotectonic database of Turkey. Bull Earthq Eng. doi:http://dx.doi.org/10.1007/s10518-016-9965-9

Web End =10.1007/ http://dx.doi.org/10.1007/s10518-016-9965-9

Web End =s10518-016-9965-9 Engdahl ER, Van der Hilst RD, Buland R (1998) Global teleseismic earthquake relocation with improved travel times and procedures for depth determination. Bull Seismol Soc Am 88:722743Engdahl ER, Villasenor A, DeShon HR, Thurber CH (2007) Teleseismic relocation and assessment of seismicity (19182005) in the region of the 2004 Mw 9.0 SumatraAndaman and 2005 Mw 8.6 Nias Island great earthquakes. Bull Seismol Soc Am 97:S43S61Ergin K, Guclu U, Uz Z (1967) A catalog of earthquakes for Turkey and surrounding area (11 AD to 1964 AD). Istanbul Technical University, Faculty of Mining Engineering, IstanbulFerrari G, Pino NA (2003) Euroseismos 20022003 a project for saving and studying historical seismograms in the Euro-Mediterranean area. Geophys Res Abstr 5, EAE03-A-05274. http://adsabs.harvard.edu/abs/2003EAEJA.....5274F

Web End =http://adsabs.harvard.edu/ http://adsabs.harvard.edu/abs/2003EAEJA.....5274F

Web End =abs/2003EAEJA.....5274F Ferrari G, Roversi Monaco C (2005) Restoration and conservation of the scientic documentation of seismology. http://storing.ingv.it/esweb/Data/restoration/restoration.html

Web End =http://storing.ingv.it/esweb/Data/ http://storing.ingv.it/esweb/Data/restoration/restoration.html

Web End =restoration/restoration.html , INGVFichtner A, Saygn E, Taymaz T, Cupillard P, Capdevillee Y, Trampert J (2013)

The deep structure of the North Anatolian fault. Earth Planet Sci Lett 373:109117. doi:http://dx.doi.org/10.1016/jepsl20130427

Web End =10.1016/jepsl20130427 Galitzin B (1914) Vorlesungen ber Seismometrie. B.G. Tubner, Leipzig and

BerlinGuidoboni E, Traina G, Comastri A (eds) (1994) Catalogue of ancient earthquakes in the Mediterranean area up to the 10th century. INGV, Rome. ISBN 88-85213-06-5Grabrovec D, Allegretti I (1994) On the digitizing of historical seismograms.

Geozika 11:2731Hancilar U (2012) Identication of elements at risk for a credible tsunami event for Istanbul. Nat Hazards Earth Syst Sci 12(107119):2012. doi:http://dx.doi.org/10.5194/nhess-12-107-2012

Web End =10.5194/ http://dx.doi.org/10.5194/nhess-12-107-2012

Web End =nhess-12-107-2012 Henry C, Das S (2002) The Mw 8.2, 17 February 1996 Biak, Indonesia, earthquake: rupture history, aftershocks, and fault plane properties. J Geophys Res 107(B11):2312. doi:http://dx.doi.org/10.1029/2001JB000796

Web End =10.1029/2001JB000796 Herak M, Allegretti I, Herak D, Duda SJ (1998) Numerical modeling of the observed Wiechert seismograph magnication. Pure Appl Geophys 152:539550Hubert-Ferrari A, Barka A, Jacques E, Nalbant S, Meyer B, Armijo R, Tapponnier

P, King G (2000) Seismic hazard in the Marmara Sea region following the 17 August 1999 Izmit earthquake. Nature 404:269273Jackson JA, McKenzie DP (1984) Active tectonics of the AlpineHimalayan

Belt between western Turkey and Pakistan. Geophys J R Astro Soc 7:185264Jackson JA, McKenzie D (1988) The relationship between plate motions and seismic moment tensors, and the rates of active deformation in the Mediterranean and the Middle East. Geophys J Int 93:4573Kalafat D, Grbz C, er SB (1987) Bat Trkiyede Kabuk ve st Manto

Yapsnn Aratrlmas. Deprem Aratrma Blteni 59:4364Kalafat D, Gne Y, Ylmazer M, Kara M, Deniz P, Kekoval K, Kuleli HS, Glen

L, zel NM (2007) A revised and extended earthquake catalogue for Turkey since 1900(M 4 0). Boazii Univ, stanbul

Kalafat D, Kekoval K, Gne Y, Kara M, Deniz P, Berberolu M (2009) A catalog of source parameters of moderate and strong earthquakes for Turkey and its surrounding area (19382008). Boazii Univ, stanbul

Kalkan E, Glkan P, Ylmaz N, elebi M (2009) Reassessment of probabilistic seismic hazard in the Marmara region. Bull Seism Soc Am 99:21272146

Kanamori H (1988a) Importance of historical seismograms for geophysical research. In: Lee WHK, Meyers H, Shimazaki K (eds) Historical seismo-grams and earthquakes of the world. Academic Press, San Diego

Kanamori H, Rivera L, Lee W H K (2010) Historical seismograms for unravelling a mysterious earthquake: the 1907 Sumatra earthquake. Geophys J Int 183:358374. ISSN 0956-540x

Karabulut H, Bouin M, Bouchon M, Dietrich M, Cornou C, Aktar M (2002) The seismicity in the Eastern Marmara Sea after the 17 August 1999 Izmit Earthquake. Bull Seismol Soc Am 92(1):387393

Karabulut H, Schmittbuhl J, zalaybey S, Lengline O, Kme-Mutlu A, Durand

V, Bouchon M, Daniel G, Bouin MP (2011) Evolution of the seismicity in the Eastern Marmara Sea a decade before and after the 17 August 1999 Izmit Earthquake. Tectonophysics 510:1727

Baarr Batrk et al. Earth, Planets and Space (2016) 68:158

Page 19 of 20

Kikuchi M, Nakamura M, Yoshikawa K (2003) Source rupture processes of the

1944 Tonankai earthquake and the 1945 Mikawa earthquake derived from low-gain seismograms. Earth Planets Space 55:159172Kennett BLN, Engdahl ER (1991) Travel times for global earthquake location and phase identication. Geophys J Int 105:429465Korkusuz ztrk Y, Meral zel N, zbakr AD (2015) States of local stressesin the Sea of Marmara through the analysis of large numbers ofsmall earthquakes. Tectonophysics 665(2015):3757. doi:http://dx.doi.org/10.1016/j.tecto.2015.09.027

Web End =10.1016/j. http://dx.doi.org/10.1016/j.tecto.2015.09.027

Web End =tecto.2015.09.027 Korkusuz Y (2012) The present day stress states in the Marmara Region. Dissertation, Department of Geophysics, Bogazici University, Istanbul. https://tez.yok.gov.tr/UlusalTezMerkezi/tarama.jsp

Web End =https:// https://tez.yok.gov.tr/UlusalTezMerkezi/tarama.jsp

Web End =tez.yok.gov.tr/UlusalTezMerkezi/tarama.jsp Kuran U, Yalciner AC (1993) Crack propagations earthquakes and tsunamis in the vicinity of Anatolia. In: Tinti S (ed) Tsunamis in the world, advances in natural and technological hazards research. Kluwer, Dordrecht, pp 159175Le Pichon X, Sengor AMC, Demirbag E, Rangin C, Imren C, Armijo R, Gorur N,

Cagatay N, De Lepinay BM, Meyer B, Saatcilar R, Tok B (2001) The active main Marmara Fault. Earth Planet Sci Lett 192(4):595616Le Pichon X, Chamot-Rooke LN, Rangin C, engr C (2003) The North

Anatolian fault in the Sea of Marmara. J Geophys Res. doi:http://dx.doi.org/10.1029/2002JB001862

Web End =10.1029/200 http://dx.doi.org/10.1029/2002JB001862

Web End =2JB001862 Lee WHK, Meyers H, Shimazaki K (eds) (1988) Historical seismograms and earthquakes of the World. Academic Press, San Diego, p 513Lienert BRE (1994) HYPOCENTER 3 2: a computer program for locating earthquakes locally, regionally and globally. Technical report, Hawaii Institute of Geophysics, PlanetologyMcKenzie DP (1972) Active tectonics of the Mediterranean region. Geophys J R

Astron Soc 30:109185McClusky S, Balassanian S, Barka A, Demir C, Ergintav S, Georgiev I, Gurkan O,

Hamburger M, Hurst K, Kahle H, Kastens K, Kekelidze G, King R, KotzevV, Lenk O, Mahmoud S, Mishin A, Nadariya M, Ouzounis A, Paradissis D, Peter Y, Prilepin M, Reilinger R, Sanli I, Seeger H, Tealeb A, Toksz MN, Veis G (2000) Global positioning system constraints on plate kinematics and dynamics in the eastern Mediterranean and Caucasus. J Geophys Res 105:56955719. doi:http://dx.doi.org/10.1029/1999JB900351

Web End =10.1029/1999JB900351 McComb HE and West JC (1931) List of seismological stations of the world,

Bulletin of the National Research Council, National Academy of Sciences, Washington, No. 82Michelini A, De Simoni B, Amato A, Boschi E (2005) Collecting, digitizing and distributing historical seismological data. EOS Trans AGU 12 July 2005, 28/86 Muller JR, Aydin A, Wright TJ (2006) Using an elastic dislocation model to investigate static Coulomb stress change scenarios for earthquake ruptures in the eastern Marmara Sea region, Turkey. Geol Soc Lond Spec Publ 253:397414. doi:http://dx.doi.org/10.1144/GSLSP20062530121

Web End =10.1144/GSLSP20062530121 Nalbant S, Hubert A, King GCP (1998) Stress coupling between earthquakes in northwest Turkey and the north Aegean Sea. J Geophys Res 103:2446924486Okal EA, Reymond D, Hongsresawat S (2012) Large, pre-digital earthquakesof the Bonin-Mariana subduction zone, 19301974. Tectonophysics. doi:http://dx.doi.org/10.1016/j.tecto.2012.09.006

Web End =10.1016/j.tecto.2012.09.006 rgl G, Aktar M (2001) Regional moment tensor inversion for strong aftershocks of the August 17, 1999 Izmit Earthquake (Mw = 7.4). Geophys

Res Lett 28(2):371374Oglesby DD, Mai PM, Atakan K, Pucci S (2008) Dynamic models of earthquakes on the North Anatolian fault zone under the Sea of Marmara: eect of hypocenter location. Geophys J Int 35:L18302Ozel NM, Necmioglu O, Yalciner AC, Kalafat D, Erdik M (2011) Tsunami hazard in the Eastern Mediterranean and its connected seas: toward a Tsunami warning center in Turkey. Soil Dyn Earthq Eng 31:598610Ozcicek B (19661967) 18 Eyll 1963 Dou Marmara Depremi Etd. Jeozik

1(2):4969zalaybey S, Ergin M, Aktar M, Taprdamaz C, Bimen F, Yrk A (2002) The

1999 Izmit earthquake sequence in Turkey: seismological and tectonic aspects. Bull Seismol Soc Am 376386Papazachos B, Papazachhou C (1997) The earthquakes of Greece. Zitis,

ThessalonikiParke JR, Minshul TA, Anderson G, White RS, McKenzie D, Kuu I, Bull JM, Grr

N, engr C (1999) Active faults in the Sea of Marmara, western Turkey, imaged by seismic reection proles. Terra Nova 11:223227

Parke JR, White RS, McKenzie D, Minshull TA, Bull J, Kuscu I, Grr N, Sengr C

(2002) Interaction between faulting and sedimentation in the Sea of Marmara, western Turkey. J Geophys Res 107(B11):2286. doi:http://dx.doi.org/10.1029/2001JB000450

Web End =10.1029/2 http://dx.doi.org/10.1029/2001JB000450

Web End =001JB000450 Parsons T (2004) Recalculated probability of M > 7 earthquakes beneath the

Sea of Marmara, Turkey. J Geophys Res 109(B05304):1029. doi:http://dx.doi.org/10.1029/2003JB002667

Web End =10.1029/ http://dx.doi.org/10.1029/2003JB002667

Web End =2003JB002667 Parsons T, Toda S, Stein R, Barka A, Dieterich J (2000) Heightened of large earthquakes near Istanbul: an interaction-based probability calculation. Science 288:661665Pierri P, De Lorenzo S, Calcagnile G (2013) Analysis of the low-energy seismic activity in the Southern Apulia (Italy). Open J Earthq Res. doi:http://dx.doi.org/10.4236/ojer.2013.24010

Web End =10.4236/ http://dx.doi.org/10.4236/ojer.2013.24010

Web End =ojer.2013.24010 Pinar N, Lahn E (1952) Trkiye Depremleri Izahli Katalogu. Bayindirlik Bakanligi,

Yapi ve Imar Isleri Reisligi, 36, 6, AnkaraPinar A, Ucer SB, Honkura Y, Sezgin N, Ito A, Baris S, Kalafat D, Matsushima M,

Horiuchi S (2009) Spatial variation of stress eld along the fault rupture zone of the 1999 Izmit Earthquake. Earth Planets Space 61:114 Pintore S, Quintiliani M, Franceschi D (2005) Teseo: a vectorizer of historical seismograms. Comput Geosci 31:12771285Pino N, Giardini AD, Boschi E (2000) The December 28, 1908, Messina Straits, southern Italy, earthquake: waveform modeling of regional seismo-grams. J Geophys Res 105(B11):2547325492Pino NA, Palombo B, Ventura G, Perniola B, Ferrari G (2008) Waveform modeling of historical seismograms of the 1930 Irpinia earthquake provides insight on blind faulting in Southern Apennines (Italy). J Geophys Res 113:B05303. doi:http://dx.doi.org/10.1029/2007JB005211

Web End =10.1029/2007JB005211 Reilinger RE, Ergintav S, Brgmann R, McClusky S, Lenk O, Barka A, Grkan

O, Hearn L, Feigl KL, akmak R, Aktu B, zener H, Toksz MN (2000) Coseismic and postseismic fault slip for the 17 August 1999, M = 7 5,

Izmit, Turkey earthquake. Science 289(5484):15191524Rivera L, Sieh K, Helmberger D, Natawidjaja D (2002) A comparative study of the Sumatran subduction-zone earthquakes of 1935 and 1984. Bull Seismol Soc Am 92(5):17211736Schlupp A, Cisternas A (2007) Source history of the 1905 great Mongolian earthquakes (Tsetserleg, Bolnay). Geophys J Int 169:11151131 Schlupp A (1996) Notectonique de la Mongolie Occidentale analyse partir de donnees de terrain, sismologiques et satellitaires. Ph.D. Dissertation, University Louis Pasteur, StrasbourgStein RS, Barka AA, Dieterich JH (1997) Progressive failure on the North Anatolian fault since 1939 by earthquake stress triggering. Geophys J Int 128:594604Stich D, Batll J, Morales J, Maci R, Dineva S (2003) Source parameters ofthe 1910 Mw = 6 1 Adra earthquake (Southern Spain). Geophys J Int

155:539546Stich D, Batll J, Maci R, Teves-Costa P, Morales J (2005) Moment tensor inversion with single-component historical seismograms: the 1909 Benavente (Portugal) and Lambesc (France) earthquakes. Geophys J Int 162:850858Saikia CK (1994) Modied frequency-wavenumber algorithm for regional seismograms using Filons quadraturemodeling of Lg waves in eastern North America. Geophys J Int 118:142158Samardjieva E, Payo G, Badal J, Lopez C (1998) Creation of a digital database for

XXth century historical earthquakes occured in the Iberian area. Pure Appl Geophys 152:139163Schweitzer J, Kennett BLN (2007) Comparison of Location Procedures: the

Kara Sea Event of 16 August 1997. Bull Seismol Soc Am 97(2):389400. doi:http://dx.doi.org/10.1785/0120040017

Web End =10.1785/0120040017 Sweeney JJ (1996) Accuracy of teleseismic event locations in the Middle East and North Africa, Lawrence Livermore National Laboratory Informal Document, UCRL-ID-125868Taymaz T, Jackson J, McKenzie D (1991) Active tectonics of the north and central Aegean Sea. Geophys J Int 106:433490Teves-Costa P, Borges JF, Rio I, Ribeiro R, Marreiros C (1999) Source parameters of old earthquakes: semi-automatic digitization of analog records and seismic moment assessment. Nat Hazards 19:205220Tun B, aka D, Irmak TS, Woith H, Tun S, Bari , zer MF, Lhr BG, Gnther

E, Grosser H, Zschau J (2011) The Armutlu Network: an investigation into the seismotectonic setting of ArmutluYalovaGemlik and the surrounding regions. Geophys Ann. doi:http://dx.doi.org/10.4401/ag-4877

Web End =10.4401/ag-4877

Baarr Batrk et al. Earth, Planets and Space (2016) 68:158

Page 20 of 20

Tobin DG, Sykes LR (1968) Seismicity and tectonics of the northeast Pacic ocean. J Geophys Res 73:38213845

Toksz MN, Shakal AF, Michael J (1979) Space-time migration of earthquakes along the North Anatolian fault zone and seismic gaps. Pure Appl Geophys 117:12581270

Ylmazer M (2009) Trkiyede 3-Bileenli Kuvvetli Yer Hareketi ve Geni Bantl Deprem Kaytlarndan Faylanma Mekanizmalarnn Belirlenmesi ve Sismotektonik Yorumlar, Ph.D. Dissertation, stanbul University

Zare M, Amini H, Yazdi P, Sesetyan K, Demircioglu MB, Kalafat D, Erdik

M, Giardini D, KhanM Asif, Tsereteli N (2014) Recent developments of the Middle East catalog. J Seismol 18(3):749. doi:http://dx.doi.org/10.1007/s10950-014-9444-1

Web End =10.1007/ http://dx.doi.org/10.1007/s10950-014-9444-1

Web End =s10950-014-9444-1 Zitter TAC, Grall C, Henry P, zeren MS, aatay MN, engr AMC, Gasperini L

De, Lpinay BM, Gli L (2012) Distribution, morphology and triggers of submarine mass wasting in the Sea of Marmara. Mar Geol 329331:5874. doi:http://dx.doi.org/10.1016/j.margeo.2012.09.002

Web End =10.1016/j.margeo.2012.09.002