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Investigation of Stress Field in Northeast of Iran With Iterative Joint Inversion of Earthquakes Focal Mechanisms

Session: Crustal Stress and Strain and Implications for Fault Interaction and Slip [Poster]

Type: Poster

Date: 4/22/2021

Presentation Time: 11:30 AM Pacific

Description: 

Northeastern Iran is one of the active seismic zones which has experienced many destructive earthquakes throughout history. The purpose of this study is to investigate the stress field using the focal mechanism solution of the earthquakes in the area with Iterative Joint Inversion Method. For this purpose, the focal mechanisms of earthquakes with a magnitude greater than 4.5 which occurred between 1992 and 2017 are reviewed. Information about these earthquakes has been gathered from the International Seismological Center (ISC). In this research, two zones for inversion and also assumption of the independence of events are considered. In this assumption, the focal mechanisms considered for the inversion are supposed to sample the unperturbedregional stress field. Hence they must be independent of each other, i.e. they mustinvolve events that are far enough from each other so that stress variations associated with any previous earthquake do not influence in a significant manner the stress field nearthe event under consideration. With this assumption, 15 earthquakes were used in the inversion. The obtained stress regime governing the region compression with a strike-slip component and strike-slip with compressive component, The maximum horizontal stress directions in two zones are N36.46W and N29.65W, respectively, which show the dominance of local pressure structures such as Freeman, Kasf-Rood and Mozurdan faults (the end section of the Kashf-Rud fault) in the region. Also, the stress regime obtained for the second zone indicates the existence of a strike slip faulting mechanism. Finally, global stress map was used to compare the results of this research.

Keywords: Maximum Horizontal Stress, Focal mechanisms, Stress field, Inversion.

Presenting Author: Fatemeh Khojasteh

Student Presenter: Yes

Authors