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Strong Motion Estimation for Active Faults with High Earthquake Potential

高地震可能性活断层的强运动估计

基本信息

批准号：
08248111
负责人：
IRIKURA Kojiro
金额：
$ 68.8万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research on Priority Areas
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-08248111/
关键词：
strong motion Prediction active faults seismic hazard dynamic source model near-field earthquakes site effect strong motion observation hybrid Green's function 強震動観測強震動レシピ震源物理地下構造波動場計算手法活断層調査ジオスライサー数値シミュレーション断層モデル /

项目摘要

Our major objectives are to obtain accurate long-term earthquake prediction by assessing hazard potential of active faults, to clarify physics of the faulting dynamics and to develop the numerical as well as semi-empirical methods for precise ground-motion modeling by computational and observational approaches. Final target is to establish the methodology of predicting strong ground motions for hypothetical active-fault earthquakes and to mitigate earthquake damage from future large earthquakes.We have been developing the above six subjects as follows : (1) Aerial photograph interpretation and paleoseismic trenching were made to date late Holocene earthquakes along the active faults for the seismic hazard evaluation on the Median Tectonic active fault system (MTL). The geometry and average slip rate of seismic source faults were obtained using the analysis of balanced cross sections based on seismic reflection profilings and boring data in some representative areas, Shinjo and Tomakoma … More i. Fault branching and directivity of rupture propagation were studied from rupture patterns of recent earthquake faultings. (2) The arresting mechanism of dynamic crack growth was studied by BIEM and compared with surface geometry of active faults. Strong pulses near the earthquake faults were calculated by near-field expression theory with a dynamic slip-rate time function. Source heterogeneity was studied by combining the results of low-frequency waveform and high frequency envelope inversions using strong ground motion and broadband recordings. Source characterizations of inland crustal earthquakes and large intra-plate earthquake were done using high-quality network data. (3) Accurate 3-D modelings of underground structures are done by joint inversion of refraction and gravity data. Site effects for sedimentary basins and shallow soil layers are well estimated from S-wave profiles derived by microtrmor array measurements, validated by direct evaluations of amplifications from earthquake records. (4) Numerical methods for propagation media with irregular interfaces are developed as a hybrid scheme with the indirect boundary element method and semi-analytical solution for flat interfaces. Seismic anisotropy are confirmed by some observation and numerical simulation in the source region of the 1997 Kagosima-hokuseibu earthquakes. (5) The results of refraction, reflection, and gravity surveys were gathered for deriving the three-dimensional underground structure in the Kobe-Hanshin area. Simulations of strong ground motions in and around heavily-damaged areas were done for examining the relation between strong ground motions and structure damage. Ground motion estimations considering source effects as well as seismic responses due to complex structures in both macro and micro scales were studied in observation and numerical techniques for the subduction and slab earthquakes. (6) Methods of strong motion prediction for future large earthquakes were developed and validated by comparing synthesized results with the observed data and damage distribution during the 1995 Hyogo-ken Nanbu and the 1994 Northridge earthquakes. Estimation of strong ground motions during the 1948 Fukui earthquake was done by hybrid simulation method. The source characterization for large inland earthquakes has been studied from statistical analyses of slip distributions with the waveform inversion.The results of the above six topics was combined to establish the methodology of estimating strong ground motions for hypothetical active-fault earthquakes. We summarize the procedure that is currently used to characterize earthquake rupture models, based on geological investigations of capable earthquake faults and seismological studies of source models. Then we propose a recipe of predicting strong ground motion form scenario earthquakes caused by active faults. Less

我们的主要目标是通过评估活动断层的潜在危险性来获得准确的长期地震预测，澄清断层动力学的物理学，并通过计算和观测方法来开发精确的地面运动建模的数值和半经验方法。最终目标是建立预测假设活动断层地震的强地面运动的方法，并减轻未来大地震的地震损失。我们一直在开发上述六个主题，具体如下：（1）通过航片判读和古地震槽探，确定了活动断裂带沿着全新世晚期地震活动的时间，对中东部活动断裂系统（MTL）进行了地震危险性评价。根据地震反射剖面和钻孔资料，在新庄和托马科马等代表性地区，利用平衡剖面分析方法，获得了震源断层的几何形状和平均滑动速率 ...更多信息 I.从近期地震断层的破裂模式研究了断层分支和破裂传播的方向性。(2)用边界元法研究了动态裂纹扩展的止裂机制，并与活断层的地表几何形状进行了比较。用动态滑动率时间函数的近场表达式理论计算了地震断层附近的强脉冲。结合低频波形和高频包络反演的结果，利用强地面运动和宽带记录研究了震源的非均匀性。利用高质量的台网资料，对内陆地壳地震和板内大地震进行了震源特征研究。(3)利用折射波和重力资料联合反演，可以得到地下结构的精确三维模型。场地对沉积盆地和浅土层的影响可以从由Microtrmor阵列测量得到的S波剖面中得到很好的估计，并通过对地震记录放大的直接评估得到验证。(4)具有不规则界面的传播介质的数值方法被开发为间接边界元法和平坦界面半解析解的混合格式。1997年鹿儿岛-北西部地震震源区的观测和数值模拟证实了地震各向异性。(5)收集了折射、反射和重力测量的结果，以得出神户坂神地区的三维地下结构。为了研究强地震动与建筑物破坏的关系，对严重破坏区及其周围的强地震动进行了模拟。在俯冲地震和板状地震的观测和数值计算技术中，研究了考虑震源效应的地震动估计以及宏观和微观尺度上复杂结构的地震响应。(6)通过与1995年兵库县南部地震和1994年北岭地震的观测资料和震害分布的比较，发展和验证了未来大地震的强震预测方法。本文用混合模拟方法对1948年福井地震的强地震动进行了估计。本文从滑动分布的统计分析和波形反演两个方面研究了内陆大地震的震源特征，并结合上述六个专题的结果，建立了一套估算假定活动断层地震的强震地面运动的方法。我们总结了目前用于表征地震破裂模型的程序，基于地质调查的地震断层和震源模型的地震学研究。在此基础上，提出了一种从活动断层引起的假想地震中预测强震的方法。少