Rupture process of 2013 Shonbe earthquake sequence

TL;DR

This study analyzes the rupture process of the 2013 Shonbe earthquake sequence using relocated seismic events and point-source inversion, revealing fault geometry, slip vectors, and rupture depth within sedimentary layers.

Contribution

It introduces a detailed seismotectonic analysis of the Shonbe earthquake sequence using Bayesian relocation and point-source inversion, providing new insights into fault geometry and rupture characteristics.

Findings

Rupture depth localized between 8-12 km.

Reverse slip with left-lateral component observed.

Fault dips southward, consistent with seismic data.

Abstract

In this study, we have used point-source approximation with the premise that it is compatible with the rupture process of the predominant faulting geometry caused by the initiation of Shonbe seismic sequence. First, all recorded earthquakes during six months after the main shock, 2013 April 9th, in the vicinity of khaki anticline near Shonbe, are relocated with the probabilistic nonlinear method based on Bayesian inference. The synthetic test is done, with the exact distribution of real stations on hand. Thus, the proper value for the parameter that can explicitly affect the error results is calculated to be 0.01. After performing relocation task, 98 relocated events with horizontal errors less than 5 km from all 373 recorded events are taken into account for further analysis of the spatial characteristics of the sequence. In advance, point source inversion is implemented for 21 events greater than 4.5 Mn. Then, supplementary investigations and stability tests are performed for the results of the main shock. Accordingly, we are convinced that the gathered results are reliable enough to be used for the seismotectonic analysis of the region resulting from the sequence. Eventually, the reverse slip vector with substantial left-lateral strike slip component (in some cases) is modeled employing the distribution of inverted centroids and resulting faulting geometry for the chosen events. A southward dip of the probable causative fault is seen, furthermore depth range of the rupture is localized within 8 to 12 km, in the lowermost part of the sedimentary cover.