Microseismic Detection and Precise Relocation of 2012 Gaoyou-Baoying M4.9 Earthquake Sequence in Jiangsu
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摘要: 本文利用江苏地区44个固定台站和4个流动台站的观测数据,采用基于人工智能的PhaseNet震相检测法,对2012年江苏高邮-宝应M4.9地震前后30d的连续数据进行地震检测,并开展REAL震相关联、绝对定位以及HypoDD精定位研究工作,获得了此次地震序列的完整目录。研究结果表明:(1)PhaseNet检测后的地震目录数量为342个,是江苏台网人工测定地震目录数量的3.7倍,震级分布范围为ML0.5~ML5.1;(2)自动检测结果丰富了高邮-宝应ML0.5~ML1.5的地震序列,并在主震前检测到大量前震序列,从主震发生前10d开始,震中区周边出现明显的地震活动增强趋势,主震后7d余震逐渐稀疏趋于平静;(3)精定位后共得到184条高精度地震目录,约为检测前精定位地震数量的3倍,地震序列震源深度主要集中在12~15 km;(4)精定位结果显示本次地震为典型的双向破裂,主震位于剖面的中部偏下位置,地震序列整体呈NNE方向展布,发震断层较为陡峭。综合本文研究、震源机制解以及地质构造资料,推测此次地震的发震断裂为柳菱断裂。
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关键词:
- PhaseNet震相检测 /
- 精定位 /
- 高邮-宝应M4.9地震 /
- 柳菱断裂
Abstract: IIn this study, we applied PhaseNet, an artificial intelligence–based seismic phase detection method, to analyze 30 days of continuous waveform data from 44 permanent and 4 temporary seismic stations surrounding the 2012 Gaoyou–Baoying M4.9 earthquake in Jiangsu Province. Following detection, we performed phase association using REAL, earthquake location, and precise relocation, ultimately producing a comprehensive catalogue of the earthquake sequence. The main findings are as follows: (1) PhaseNet detected 342 events, which is approximately 3.7 times more than the number recorded in the official Jiangsu Seismic Network catalogue. The detected events range in magnitude from ML 0.5 to ML5.1. (2)The automatic detection significantly enriched the Gaoyou–Baoying seismic sequence, particularly for small-magnitude events ( ML0.5~1.5). A large number of foreshocks were identified preceding the mainshock, with a clear increase in seismic activity within 10 days before the mainshock. In contrast, aftershock activity markedly decreased and became more spatially dispersed within 7 days after the mainshock. (3) After precise relocation, 184 high-precision earthquake events were identified—approximately three times the number of accurately located events prior to this analysis. These events are primarily concentrated at depths of 12~15km. (4)The earthquake sequence exhibits characteristics of bi-directional rupture, with the mainshock occurring in the lower section of the central rupture zone. The sequence aligns along a NNE-trending, steeply dipping fault. Based on the spatial distribution of the seismic sequence, source mechanism solutions, and regional geological data, we infer that the Liuling Fault is the likely seismogenic structure responsible for the 2012 Gaoyou–Baoying M4.9 earthquake. -
表 1 江苏一维速度模型
Table 1. The one-dimensional velocity model in Jiangsu
层深/km VP/(km·s−1) VS/(km·s−1) 0 3.70 2.14 5 5.10 2.92 10 5.44 3.14 15 6.03 3.48 20 6.34 3.66 25 6.52 3.76 40 7.02 4.05 -
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