ISSN 1004-4140
CN 11-3017/P

海南岛及邻区中小地震重定位

Relocation of Moderate-to-small Earthquakes in and Around Hainan Island

  • 摘要: 本研究收集中国地震台网中心2008年11月18日至2023年10月26日期间由68个地震台站记录的海南及邻区415次地震事件的6090条P波和5545条S波震相到时数据,采用双差定位方法开展重定位研究,最终获得313次地震的高质量震源参数。研究结果显示,地震在E-W向、N-S向和垂直向上平均定位误差分别为0.14、0.15和0.22 km。地震主要集中在海南岛东北部和西南部,优势深度为5~15 km。在海南岛东北部,地震主要呈现出NNE-SSW向带状分布,与NW-SE向的铺前−清澜断裂、海口−云龙断裂及长流−仙沟断裂并非完全一致。海南岛西南部地区自2019年三亚4.2级地震后发育了一系列中小地震震群,地震主要发生在九所−陵水断裂附近及乐东−田独断裂西段。这些结果表明,地震的发生可能与断裂活动有关。结合前人其他学科研究结果,海南岛西南部地区地震时序变化特征可能暗示三亚4.2级地震对乐东震群的形成有一定促进作用。海南岛及邻区地震的发生可能受到断裂带活动、火山活动和流体作用的共同影响。

     

    Abstract: In this study, 6090 P-wave and 5545 S-wave arrival time data recorded by 68 seismic stations during 415 seismic events in and around Hainan Island between November 18, 2008, and October 26, 2023, were collected from the China Earthquake Networks Center observational bulletins. The double-difference algorithm was used for relocation, and eventually, the high-quality source parameters of 313 earthquakes were obtained. Our results show that the average location errors of earthquakes in the E-W, N-S, and vertical directions are 0.14, 0.15, and 0.22 km, respectively. The earthquakes are concentrated mainly in the northeastern and southwestern Hainan Island, with the dominant depths being 5~15 km. In the northeastern Hainan Island, the earthquakes present predominantly an NNE-SSW banded distribution, which is not consistent with the NW-SE Puqian-Qinglan, Haikou-Yunlong, and Changliu-Xiangou Faults. Since the 2019 Sanya M 4.2 earthquake, a series of moderate-to-small seismic swarms have been developed in southwestern Hainan Island. The earthquakes occurred predominantly near the Jiusuo-Lingshui Fault and west of the Ledong-Tiandu Fault. This suggests that the occurrence of earthquakes may be related to fault activity. Combined with the findings of previous studies, the spatiotemporal seismic changes in southwestern Hainan Island suggest that the 2019 Sanya M4.2 earthquake likely promoted the formation of the Ledong seismic swarm. The occurrence of earthquakes in and around Hainan Island is jointly affected by fault zone activity, volcanic activity, and fluid action.

     

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