日本地球惑星科学連合2023年大会

講演情報

[E] 口頭発表

セッション記号 U (ユニオン) » ユニオン

[U-02] Remote Sensing Role in Sustainable Development

2023年5月24日(水) 09:00 〜 10:15 展示場特設会場 (1) (幕張メッセ国際展示場)

コンビーナ:Usman Muhammad(Life and Environmental Science (LES) Department)、阿部 隆博(三重大学大学院生物資源学研究科)、座長:Usman Muhammad(Life and Environmental Science (LES) Department)、阿部 隆博(三重大学大学院生物資源学研究科)

10:00 〜 10:15

[U02-04] Fault slip distribution of the 14 November 2021 Fin doublet earthquakes, Southeast Iran, from InSAR measurements

*Jiaqing Wang1,2Yosuke Aoki2Yan Cui3,2Lang Xu4,2、Guohong Zhang5、Yingfeng Zhang5、Guangli Su1、Iraj Rouhi6 (1.First Monitoring and Application Center, China Earthquake Administration, China、2.Earthquake Research Institute, the University of Tokyo、3.Hohai University, China、4.Southwest Jiaotong University, China、5.Institute of Geology, China Earthquake Administration, China、6.University of Tehran, Iran)

キーワード:Fin earthquake, blind thrust fault, InSAR, BOI

The ambiguity in the fault geometry of buried thrust earthquakes of moderate magnitude occurring in folded thrust zones always brings uncertainties in understanding the interplay between faulting and folding. On 14 November 2021, doublet earthquakes (Mw6.1 and Mw6.4) struck the Fin area in the southeastern Zagros Mountains, providing an opportunity to investigate the interaction between folding and faulting. We use DInSAR and BOI to obtain the coseismic surface deformation with different viewing geometries based on Sentinel-1A and ALOS2 PALSAR images, and reconstruct the 3D deformation by combining all measurements using a weighted least-squares method. We find significant lateral motion along the NNE in the uplifted region near the epicenter, which cannot be reproduced by either the slip on a single N or S dipping reverse fault models. This finding is inconsistent with what had been found before. Here, based on the geomorphological analysis of the epicentral area and the interpretation of the deformation field, we assume that coseismic slip occurred on complex faults consist of a forward and a backward thrust fault. Our inversion results indicate that the first mainshock occurred on a N dipping thrust fault with near east-west orentiation located between Namak and Handun anticlines, and the second mainshock occurred north of Handun anticline along a S-dipping thrust fault oriented W-E, produced most of the subsidence deformation in the south of epicenter. The scalar seismic moments released by the twin shocks from our analysis are equivalent to Mw6.45 and Mw6.10, which are consistent with the moment magnitudes reported by USGS and GCMT, respectively. The Coulomb stress analysis based on the slip distributions of the first mainshock reveals a trigger for the second event. The faulting mechanism of the doublet earthquakes suggests that anticlines and synclines in this area may play a more important role in controlling the way to release of accumulated stress caused by the long-term convergence of the Arabian Plate with the Eurasian Plate and local folding or faulting.