报告地点：腾讯会议(会议ID：411 4788 6096）
报告时间：2020-12-04 从 15:00 到 16:00
报告人：盛一笑
报告人简介：
盛一笑，2014年于中国科学技术大学少年班学院，获得地球物理学士学位，2020年六月于美国斯坦福大学获得博士学位，2020年九月起在法国格勒诺布尔-阿尔卑斯大学地球科学研究所任职博士后。主要研究方向包括地震识别和定位，速度变化监测和地球背景噪音的应用。
报告题目：Depth Constraints on Coseismic Velocity Changes from Frequency-Dependent Measurements of Repeating Earthquake Waveforms
报告内容简介
We revisit velocity changes caused by the 2004 Parkfield earthquake through the analysis of the coda of repeating earthquakes. Our results reveal the change to be strongly frequency-dependent. Low-frequency components of the coda of repeating earthquakes are more affected by the velocity alteration than high-frequency components. We interpret this to indicate that the coseismic velocity reduction primarily occurs at a shallow depth, and is expressed in low-frequency energy resulting from reverberations near the Earth’s surface. This can only be observed at low-frequencies because the shallow crust is highly dissipative. The high-frequency component is relatively unaffected as it is comprised of body waves scattered throughout the crust. We support this argument with direct observations of seismic wavefields across a wide range of depths in the shallow crust, supplemented by using downhole geophones and distributed acoustic sensing (DAS) measurements.