Earthquake swarms near the Mór Graben, Pannonian Basin (Hungary): implication for neotectonics

Abstract

The central part of the Pannonian Basin is characterised by low to medium seismicity. North central Hungary is one of the most dangerous areas of the country in terms of earthquakes, which also includes the area of the Mór Graben where some of the largest earthquakes occurred in Hungary’s history. Recent activity has been observed in the Mór Graben. It has been established that earthquake swarms occur quite frequently in the graben. To further study these events, we deployed a temporary seismic network that operated for 20 months. Using the temporary network stations as well as permanent stations from the Kövesligethy Radó Seismological Observatory and the GeoRisk Ltd. networks we registered 102 events of small magnitudes. In this paper, we demonstrate and compare three different event detection methods based on the registered waveforms by the permanent and temporary stations to find the optimal one to collect a complete swarm list in the Mór Graben. After the hierarchical cluster analysis, we relocated the hypocentres using a multiple-event algorithm. Our results demonstrate that the most successful detector in this case is the “Subspace detector.” We managed to create a complete list of the events. Our results indicate that the Mór Graben is still seismically active.