JpGU-AGU Joint Meeting 2017

講演情報

[EJ] 口頭発表

セッション記号 S (固体地球科学) » S-SS 地震学

[S-SS12] [EJ] 活断層と古地震

2017年5月23日(火) 13:45 〜 15:15 A04 (東京ベイ幕張ホール)

コンビーナ:小荒井 衛(茨城大学理学部理学科地球環境科学コース)、杉戸 信彦(法政大学人間環境学部)、松多 信尚(岡山大学大学院教育学研究科)、安江 健一(日本原子力研究開発機構)、座長:松多 信尚(岡山大学大学院教育学研究科)、座長:後藤 秀昭( 広島大学大学院文学研究科)

14:15 〜 14:30

[SSS12-21] Preliminary study on related faults and triggering mechanism of the 9.12 Gyeongju earthquake (ML=5.8)

*Taehyung Kim1Junho Lee1Young-Seog Kim1 (1.Dept. of Earth & Environmental Sciences, School of Earth Environmental Hazard System Science, Pukyoung National University)

キーワード:Gyeongju Earthquake, Active fault, Earthquake mechanism, LiDAR, Aftershock distribution, Fault damage zone

The 9.12 Gyeongju Earthquake (ML=5.8), the biggest instrumental earthquake in South Korea, are followed by hundreds of small to medium magnitude of aftershocks around the Hwagok reservoir in Naenam-myeon, Gyeongju, Korea. This earthquake is a shock to Korean people who believed that a Korean peninsula is a safe place from earthquakes. It was enough people to think the importance of earthquake and active fault. One of the hottest issues after the earthquake is the related active fault. We directly visited the epicenter area and carried out field work to find surface ruptures or any related faults, and furthermore, we have done lineament analysis based on pre-existing satellite images and new LiDAR data as well as fore/aftershocks distribution. Although we could not find any surface ruptures related to this earthquake, there are many N-S to NNE-SSW trending lineaments and minor dextral faults, which are parallel to the main Yangsan Fault and a subsidiary Deokcheon fault. The two major faults are geometrically linked by several NE-SW trending connecting lineaments in LiDAR Image. Focal mechanisms of the 9.12 Gyeongju Earthquake represent NNE trending dextral strike-slip fault, and distributions of fore/aftershocks indicate the concentration in the linking damage zone between the two major faults. Based on these preliminary studies, the 9.12 Gyeongju Earthquake may be triggered by a connecting fault in the linking damage zone of the two NNE-SSW trending faults (Yangsan fault and Deokcheon fault) with a dextral strike-slip sense.