Spatial time cluster analysis and earthquake mechanism for unknown active fault (Kalatoa fault) in the Flores Sea

Abstract

The Flores earthquake (Mw 7.3) occurred on December 14, 2021, in the Flores Sea and was responsible for an unknown active fault known as the Kalatoa fault. The earthquake's epicenter was located around 100 km north of Flores Island, Indonesia. We analyzed the different earthquake mechanisms using moment tensor (MT) inversion for the mainshock and the largest aftershock with the seismic network at a distance up to 700 km from the epicenter. The results confirm that the mainshock mechanism of the earthquake was NW–SE orientated left-lateral fault with a magnitude estimation Mw of 7.30 ± 0.04 and depth of 9.50 ± 2 km. On the other hand, the aftershock mechanism of the earthquake was NW–NS orientated with a thrusting fault having an Mw of 5.95 ± 0.02 and a depth of 7.5 ± 2 km. The earthquake catalog data from November 2008 to March 2022 are considered in this study to rescale their space–time-depth-magnitude (STDM) time series on a logarithmic scale. Based on the break in time series, we tried to explain the earthquake events as preshocks and aftershocks of the Flores earthquake. Finally, we used wavelet plots of the STDM time series for effective visualization. The localization of lower and high frequency with data points confirms the instant events at which the seismic peak occurred. The outcomes from this study align with the efforts to understand future earthquakes' characteristics elsewhere.