有限断层模型在2015年9月16日智利Mw8.3级地震海啸数值模拟中的应用与评估

摘要

On September 16,2015,at 19:54 (local time)a magnitude Mw 8.3 earthquake took place off the coast of central Chile,focal depth of 25 km.Meanwhile,the earthquake with rupture zone 200 km long and 100 km wide triggered moderate intensity teletsunami.The tsunami impacted approximately 700 km of the coast of Chile,some areas tsunami reached amplitudes near 5 m and tsunami run-up exceeded 13 m.Tsunami waves were subsequently recorded by more than 40 Deep-ocean Assessment and Reporting of Tsunami (DART)buoys in the Pacific Ocean and more than 200 tide gauges throughout the Pacific Ocean,a rich supply of data which study the tsunami propa-gation scenarios in near-filed and deep-water.This paper used the finite fault models and adaptive refinement algo-rithms to build a well computational efficiency and high resolution numerical tsunami model.We analyzed the telet-sunami propagation characteristics.The results show that by using the established model can well reproduce the far-field and near-field tsunami process,especially on the near-field the simulation results fit well with the observa-tional data.It indicates that the finite fault model can better depict the near-field,especially the rupture characteris-tics and provide more accurate source information.The fine prediction of tsunami propagation characteristics can be achieved by the finite fault model and high resolution numerical tsunami model.In this paper,using the observa-tion data and simulation results,analyzed the frequency dispersion of the tsunami wave and its influence on the model.Meanwhile,carried out a brief summary of the typical characteristics of the tsunami wave.The wavelet a-nalysis show that the tsunami energy is concentrated in the period band of around 10-50 min.These wave charac-teristics are not involved in the current tsunami warning information,but they are very important parameters.Fur-ther research on these characteristics will provide technical support for the improvement of tsunami warning infor-mation and warning products.%2015年9月16日22时54分(当地时间)智利中部近岸发生Mw 8.3级地震,震源深度25 km.同时,强震的破裂区长200 km,宽100 km,随之产生了中等强度的越洋海啸.海啸影响了智利沿岸近700 km的区域,局部地区监测到近5 m的海啸波幅和超过13 m的海啸爬坡高度.太平洋区域的40多个海啸浮标及200多个近岸潮位观测站详细记录了此次海啸的越洋传播过程,为详细研究此次海啸近场及远场传播及演化规律提供了珍贵的数据.本文选择有限断层模型和自适应网格海啸数值模型建立了既可以兼顾越洋海啸的计算效率又可以实现近场海啸精细化模拟的高分辨率海啸模型.模拟对比分析了海啸的越洋传播特征,结果表明采用所建立的模型可以较好地再现远场及近场海啸特征,特别是对近场海啸的模拟结果非常理想.表明有限断层可以较好地约束近场、特别是局部区域的破裂特征,可为海啸预警提供更加精确的震源信息,结合高分辨率的海啸数值预报模式实现海啸传播特征的精细化预报.本文结合观测数据与数值模拟结果初步分析了海啸波的频散特征及其对模型结果的影响.同时对观测中典型的海啸波特征进行的简要的总结.谱分析结果表明海啸波的能量主要分布在10~50 min周期域内.这些波特征提取是现行海啸预警信息中未涉及,但又十分重要的预警参数.进一步对这些波动特征的详细研究将为海啸预警信息及预警产品的完善提供技术支撑.