Migrating Foreshocks Before the 2014 M6.5 Ludian, Yunnan Earthquake
Session: New Insights Into the Preparatory Phase of Earthquakes From Tectonic, Field and Lab Experiments III
Type: Oral
Date: 4/19/2021
Presentation Time: 05:15 PM Pacific
Description:
Large mainshocks are sometimes preceded by seismic activity also known as “foreshocks”. Many researchers found acceleration/migration of foreshock activities before mainshock. The relationship between mainshock and foreshocks is still an open question. In this paper, we take the 2014 MS6.5 Ludian, Yunnan Earthquake as a case to study the seismic activity before the mainshock. We use the GPU-based Match and Locate method (Zhang and Wen, 2015; Liu, 2020) to detect and locate the small foreshocks that may be omitted in the original catalog. We first relocated the original earthquake sequence catalog by tomoDD method (Zhang and Thurber, 2003), and then use the waveforms of 857 earthquakes (ML≥1.0 before mainshock and ML≥2.0 after mainshock) occurred in 2014 as templates to scan the continues waveforms, 9 seismic station near the mainshock is used for the detection. We identified 588 earthquakes in the study area (26.7°-27.5°N, 102.9°-103.7°E) during the last 34 days before the Ludian mainshock. We plot the space-time evolution of the newly detected events with respect to the reference axis distance from the initial point of the main shock rupture. We found seismic activity is accelerated and earthquakes are migrated toward the rupture initial point of the mainshock during the last 24-19 days before the mainshock. However, after that until the mainshock, the seismicity near the seismogenic fault is relative quiet.
This study was supported by the National Key R & D Program of China (2018YFC1503305).
References
Liu Ming et al. 2020. Graphics Processing Unit-Based Match and Locate (GPU-M&L): An Improved Match and Locate Method and Its Application. Seismol. Res. Lett. 91, 1019–1029.
Zhang Haijiang and Turber H Clifford. 2003. Double-Difference Tomography: The Method and Its Application to the Hayward Fault, California. Bulletin of the Seismological Society of America, Vol. 93, No. 5, pp. 1875–1889, October 2003.
Zhang Miao and Wen Lianxing. 2015. An effective method for small event detection: match and locate (M&L). Geophys. J. Int. 200, 1523–1537.
Presenting Author: Shiguang Deng
Student Presenter: No
Authors
Shiguang Deng Presenting Author Corresponding Author dengsg@seis.ac.cn China Earthquake Networks Center |
Haikun Jiang jianghaikun@seis.ac.cn China Earthquake Networks Center |
Yawei Ma yawei_m@seis.ac.cn China Earthquake Networks Center |
Jin Song songjinbent@seis.ac.cn China Earthquake Networks Center |
Yanru An anyanru@seis.ac.cn China Earthquake Networks Center |
Yue Wang wangyue@seis.ac.cn China Earthquake Networks Center |
Mengyu Xie xiemengyu@seis.ac.cn China Earthquake Networks Center |
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Migrating Foreshocks Before the 2014 M6.5 Ludian, Yunnan Earthquake
Category
New Insights Into the Preparatory Phase of Earthquakes From Tectonic, Field and Lab Experiments