Numerical Modeling of Moderate Magnitude Earthquakes

每年都会发生大地震，给世界各地的社区带来毁灭性的打击。在过去的十年里，印度、土耳其、台湾、日本和美国的地震造成了数十亿美元的损失和数千人的伤亡。产生适当的地震地面运动时程是设计抗震结构的必要步骤，除了了解地震波的传播、地壳地质和场地的土壤条件外，还需要了解震源。因此，地震工程是一个跨学科的领域，结合了结构工程、岩土工程、地震学和地质学的专业知识。提出的合作工作弥合了工程和地震学在中等震级地震数值模拟之间的差距。所提出的工作的智力优点是采用4到5级(M)范围内的中等大小地震来了解区域波传播，震源和局部场地效应，并将这些结果外推到该地区的大地震和强地面运动。通过仔细计算和验证震源、路径和地点对中等地震的影响，我们假设我们可以定性地。预测大地对大地震的反应特征。我们的第二个假设是，在地壳模型中包含详细的土壤条件将导致比目前常见的更精确的模拟地面运动（精确到更高的频率）。我们的研究计划包括四个具体任务：1)确定旧金山湾和大阪湾地区最近三次中等地震的震源机制。2)为每个研究区域（旧金山湾和大阪湾）开发和验证波传播的地壳模型。3)通过评估垂直阵列的预测波形来评估土层的影响。4)验证大地震的方法。研究团队是一个多学科的研究团队，由地震学和地质/岩土地震工程专家组成。百色是一名地质/岩土地震工程师，具有研究波传播和场地效应的经验。百色将领导该项目，以确保结果具有工程用途和重要性。Dreger和Abercrombie是地震学家，他们将在震源表征（Abercrombie和Dreger）和波传播技术（Dreger）领域提供指导和积极参与。这项研究的广泛影响有三方面。首先，该方法可用于低地震活动性地区对大地震的区域地震效应预测。因此，拟议的研究将改进地面运动模拟并减少地震损失。其次，当地震学家和工程师在研究和课堂上聚集在一起时，这项工作将广泛地影响所有三所大学的教育环境。最后，通过PI的持续努力，来自代表性不足群体的研究生和本科生将被招募参与这项研究。

Large earthquakes occur every year, devastating communities around the world. In the past ten years, earthquakes in India, Turkey, Taiwan, Japan, and the United States have caused billions of dollars of damage and thousands of casualties. Producing appropriate earthquake ground motion time histories, a necessary step for designing earthquake resistant structures, requires an understanding of the earthquake source in addition to an understanding of the wave propagation, crustal geology, and the soil conditions at the site. As a result, earthquake engineering is an interdisciplinary field combining expertise in structural engineering, geotechnical engineering, seismology, and geology. The proposed collaborative work bridges the gap between engineering and seismology in the numerical modeling of moderate magnitude earthquakes. The intellectual merit of the proposed work is to take moderate-sized earthquakes in the magnitude (M) range from 4 to 5 to understand regional wave propagation, earthquake sources, and local site effects with the long term goal of extrapolating these results to large earthquakes and strong ground motions for that region. By carefully accounting for and validating the source, path, and site effects in a moderate earthquake, we hypothesize that we can .qualitatively. predict the characteristics of ground response for large earthquakes. Our second hypothesis is that including detailed soil conditions in a crustal model will result in more accurate simulated ground motions (accurate to a higher frequency) than is currently common. Our research plan consists of four specific tasks: 1) Determine the source mechanisms of three recent moderate earthquakes each in the San Francisco Bay and in the Osaka Bay regions. 2) Develop and validate a crustal model for wave propagation for each study region: San Francisco Bay and Osaka Bay. 3) Evaluate effect of the soil layer by assessing predicted waveforms at Vertical Arrays. 4) Validate method for large earthquakes. The research team is multidisciplinary and consists of experts in seismology and geology/geotechnical earthquake engineering. Baise is a geology/geotechnical earthquake engineer, with experience studying wave propagation and site effects. Baise will lead the project to ensure that the result is of engineering use and importance. Dreger and Abercrombie are earthquake seismologists and will provide guidance as well as active participation in the areas of source characterization (Abercrombie and Dreger) and wave propagation techniques (Dreger). The broader impact of this study is three-fold. First, the proposed method can be used in areas of low seismicity to predict regional earthquake effects for large earthquakes. The proposed research will therefore improve ground motion simulations and reduce seismic losses. Secondly, the effort will broadly impact the educational environment at all three universities involved when seismologists and engineers are brought together in research and in a classroom. Finally, through continuing efforts of the PI both graduate and undergraduate students from underrepresented groups will be recruited to participate in this research.