马尼拉俯冲带最大可能地震对南海诸岛的海啸灾害评估  

Tsunami hazard assessment to South China Sea Islands induced by the earthquake with maximum possible magnitude in the Manila subduction zone

作　　者：赵广生 牛小静[1,2,3] ZHAO Guangsheng;NIU Xiaojing(State Key Laboratory of Hydroscience and Engineering,Tsinghua University,Beijing 100084,China;Key Laboratory of Hydrosphere Sciences of the Ministry of Water Resources,Tsinghua University,Beijing 100084,China;Department of Hydraulic Engineering,Tsinghua University,Beijing 100084,China)

机构地区：[1]清华大学水圈科学与水利水电工程全国重点实验室,北京100084 [2]清华大学水利部水圈科学重点实验室,北京100084 [3]清华大学水利水电工程系,北京100084

出　　处：《清华大学学报（自然科学版）》2024年第4期612-618,共7页Journal of Tsinghua University(Science and Technology)

基　　金：国家自然科学基金面上项目(51779125);水圈科学与水利水电工程全国重点实验室自主课题(2022-KY-05)。

摘　　要：马尼拉俯冲带是南海可能发生大型地震海啸的地质构造带,一旦发生大地震海啸将对南海沿岸和岛礁地区造成严重灾害。该文通过分析马尼拉俯冲带最大地震震级并模拟诱发海啸过程,评估在最大震级地震发生时南海岛礁面临的海啸危险性。研究综合考虑地震震中、震源深度和断层滑动非均匀性等因素对海啸的影响,模拟了最大震级条件下70万个可能的海啸情景。其中,基于GPS大地测量数据的俯冲带闭锁反演和历史地震数据,选取评估结果500年一遇地震震级8.9级作为最大可能地震。研究给出了南海主要岛礁在发生8.9级地震时的岸外海啸波高,结果表明:即使在同一震级下,海啸波高也有很大的随机性,东沙岛的海啸波高可从1.8 m增加到6.2 m。断层非均匀性对海啸波高影响显著,忽略断层非均匀滑动分布的传统模型会低估海啸波高约20%~50%。从空间分布来看,西沙宣德群岛的南沙洲、南岛和北岛,以及东沙群岛的海啸危险性最大,海啸波高超过4 m。[Objective]The Manila subduction zone is the primary source of potential large tsunamis in the South China Sea,which may result in severe coastal disasters.This study aims to evaluate the tsunami hazards faced by South China Sea Islands caused by earthquakes with maximum magnitudes through assessing the earthquake with maximum possible magnitude in the Manila subduction zone and simulating the process of induced tsunamis.[Methods]The seismic potential was evaluated using the negative dislocation inversion model TDEFNODE based on GPS horizontal velocity field data.The acquired distribution of the locking and slip deficit along the Manila subduction zone was first used to assess the seismic potential.The earthquakes with a magnitude of 8.9 and a 500-year return period were selected as the maximum possible earthquake to design extreme earthquake tsunami events.This study comprehensively considered the impact of the epicenter,focal depth,and heterogeneity in the fault slip on tsunamis,and about 700000 tsunami events under the condition of magnitude 8.9 were simulated for further evaluation.Both uniform and heterogeneous slip models were adopted to describe fault slips in the tsunami events.Considering that a larger fault slip is more likely to occur in areas with a higher degree of fault locking,the distribution of fault locking was also introduced into the heterogeneous slip model as a constraint for the random slip distribution.The tsunami events were simulated by the unit-source superposition method proposed by our group previously,which could efficiently simulate the propagation of tsunami waves based on a precomputed database and provided the offshore tsunami wave heights of major islands with small computational cost.[Results]The findings revealed that even under the same magnitude,the height of tsunami waves exhibited significant randomness.The tsunami wave height in Dongsha Island varied between 1.8 m and 6.2 m during 8.9-magnitude earthquake tsunami events.The heterogeneity of fault slip had a significant im

关 键 词：马尼拉俯冲带 TDEFNODE 断层闭锁 南海诸岛 海啸灾害评估 

分 类 号：P753[交通运输工程—港口、海岸及近海工程]