A seismic quiescence before the 2017 Mw 7.3 Sarpol Zahab (Iran) earthquake: Detection and analysis by improved RTL method

Publication date: Available online 22 March 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Stefania Gentili, Antonella Peresan, Mohammad Talebi, Mehdi Zare, Rita Di GiovambattistaAbstractA major earthquake, with magnitude Mw 7.3, struck Sarpol Zahab (Kermanshah province, Iran) on November 122,017, causing extended damage and casualties. The epicenter was located in the Northwestern part of the Zagros mountain range, an active belt originated by the Arabia-Eurasia collision.We explore seismicity preceding this earthquake, by using the Iranian Seismological Center instrumental earthquake catalog (IGTU), with the aim to identify possible anomalies in background seismicity that can be related with this and other future large events. For this purpose, we used a method for intermediate term forecasts of large earthquakes, namely the Region Time Length (RTL) algorithm, which analyzes declustered catalogs and is sensitive to quiescences that may precede major earthquakes. RTL has been progressively refined and has been applied in several regions worldwide during the last decades. To decluster the earthquake catalog we used a quite novel approach, based on the nearest-neigbour distances between events in the space-time-energy domain, a method that preserves the background seismicity while removing the clustered component.The retrospective application of RTL algorithm to the area surrounding the mainshock epicenter highlights two significant quiescences: one precedi...
Source: Physics of the Earth and Planetary Interiors - Category: Physics Source Type: research