东南亚地震活动与b值的时空分布特征

Spatiotemporal Distribution Characteristics of Seismicity and b-Value in Southeast Asia

东南亚地区是“21世纪海上丝绸之路”(以下简称“海洋丝路”)的重要组成部分,该区历史上曾发生十余次巨大地震,地震及其次生地质灾害是威胁东南亚地区经济社会发展和国际合作的主要自然灾害。系统梳理该区地震活动的时空分布特征及评估未来灾害风险格局,对于推进“一带一路”倡议实施及区域经济社会可持续发展具有重要意义。文章基于东南亚地区1900年以来M≥5地震的时空分布统计分析和地震b值计算,揭示出该区的地震活动在时间上表现出活跃期与平静期交替变化的特征;空间上表现出明显的聚集效应,成丛性强且主要集中在5个地震统计区内,其中印尼—马来多岛弧盆系地震区和菲律宾群岛地震区的地震活动最为活跃。总体而言,东南亚5个地震区的b值偏低,在0.42~0.91之间。该区内的地震b值也存在时空差异,受大地震事件、俯冲带年龄、活动断裂带和震源深度等众多因素影响,但主控因素在不同区域有所不同。地震b值时空变化特征对区域地震活动预测具有启示作用。上述认识为推进“海洋丝路”工程建设和“一带一路”防灾减灾对策提供了科学支撑。

Southeast Asia,an important region of the“21st-Century Maritime Silk Road”,has been struck by more than ten giant devastating earthquakes historically.Accordingly,the earthquakes and associated geological hazards are the main natural hazards threatening the socio-economic development and international cooperation in this region.Systematic investigation on spatiotemporal distribution of the seismicity and the assessment of the future earthquake hazard risk hold key for advancing the“the Belt and Road”Initiative and socio-economic sustainable development in the region.Based on the analysis of the spatiotemporal distribution of Magnitude≥5 earthquakes in Southeast Asia since 1900 and the calculation of regional seismic b-values,our results show that the seismicity in Southeast Asia is featured by the alternations of active and quiescent periods temporally.The seismicity also demonstrates a spatially strong clustering,mainly concentrating on five seismic sub-areas.Among which the Indonesia-Malay archipelagic area and the Philippine islands show intensive earthquake activities.Generally the seismic b-values for this region are low,ranging between 0.42 and 0.91,but show an obviously spatiotemporal variation as well.Seismic b-value of Southeast Asia is mainly affected by the factors that include the large earthquake events,the age of subduction zones,the active fault zone and the focal depth,but their relative contributions are various for different areas.The spatiotemporal variation of seismic b-value is of significance for regional earthquake prediction.The results could provide some scientific supports for reinforcing engineering infrastructures of the Maritime Silk Road and the mitigation of the earthquake hazards for the commencement of the Belt and Road Initiative.