Seismic strong motion estimation with risk evaluation in Mexico City

我们调查了1985年墨西哥城地震中，在湖底区域引起大量建筑物破坏的大振幅长周期强震。我们合理地估计了强烈的运动，并在湖床区进行了建筑物的响应分析。对墨西哥城地震危险性进行了评估，并总结了地震灾害防御对策。为此，我们进行了以下3个研究主题：1.强运动。(1)我们分析了在墨西哥城的湖床区的三维，小阵列站记录的强烈运动。我们估计了一个理论波场，使用浅和深结构。同时，从理论上分离了体波和表面波。此外，我们进行了数值模拟的体波传播，考虑非线性和沉降的土壤。(2)我们分析了在墨西哥城的几个钻孔站记录到的强烈运动，并调查了不同岩土区域的波场。我们估计了一些理论波场使用深层结构，并指出，面波激发的墨西哥火山带。2.建筑物。(1)本文建立了考虑强震特性的三维非线性土-建筑物相互作用分析方法。我们进行了相互作用分析，低高层建筑在墨西哥城的湖床区在假设的格雷罗地震，这是类似于1985年的地震。在1985年的地震中，我们解释了许多中层建筑物的损坏。(2)我们在墨西哥城的不同岩土工程区进行了同样的分析，并解释了当地的差异损害水平。我们开始改善墨西哥城现有的地震风险评估系统，通过考虑强震特性和建筑物的反应。此外，我们正在估计墨西哥城由于一些地震造成的经济损失。

We investigate large-amplitude long-period strong motions with long duration, which caused much building damage in the lakebed zone of Mexico City during the 1985 earthquake. We estimate strong motions reasonably, and perform a building response analysis in the lakebed zone. We evaluate seismic risk in Mexico City, and summarize countermeasures for earthquake disaster prevention. For these purposes, we performed the following 3 research themes.1.Strong motions. (1) We analyzed strong motions recorded at a 3-dimensional, small array station in the lakebed zone of Mexico City. We estimated a theoreticalwavefield, using a shallow and deep structures. Also, we separated body andsurface waves theoretically. Furthermore, we performed a numerical simulation for body-wave propagation, considering nonlinearity and subsidence of soils. (2) We analyzed strong motions recorded at several borehole stations in Mexico City, and investigated wavefields in different geotechnical zones. We estimated some theoretical wavefields using deep structures, and indicated that surface waves were excited by the Mexican Volcanic Belt.2.Buildings. (1) We developed a 3-dimensional nonlinear soil-building interaction analysis, which considered characteristics of strong motions. We performed the interaction analysis for low- to high-rise buildings in the lakebed zone of Mexico-City during the hypothetical Guerrero earthquake, which is similar to the 1985 earthquake. We interpreted much damage to mid-rise buildings during the 1985 earthquake. (2) We conducted the same analysis in different geotechnical zones of Mexico City, and interpreted local differences in damage level.3.Urban disaster prevention. We started to improve an existing seismic risk evaluation system for Mexico City, by considering strong-motion characteristics and building responses. Also, we are estimating economical damage in Mexico City due to some earthquakes.