Broadband Seismological Investigations of Earth Structure and Earthquake Sources

由Thorne Lay教授监督的UCSC地震研究项目使用全球宽带数字地震数据（以及高速GPS数据和海啸记录）来解决有关地球结构和地震破裂过程的基本问题。对地震产生的记录波场进行定量分析，以解决下列基本问题：（1）对智利、明打威和苏门答腊近海最近发生的大地震进行高速GPS数据、宽频带地震体波和面波以及海啸观测的联合反演，以了解破裂是如何发展的以及断层在每种情况下是如何滑动的;（2）将利用地震波振动的强震和强震记录，对板块边界巨型逆冲断层及其附近的地震进行频谱分析，以进一步发展和测试最近提出的巨型逆冲断层地震辐射随深度变化的模型;（三）将对深源地震的地震记录进行叠加和偏移，以获得上地幔反射率和不均匀性的图像（4）新的叠加和迁移方法将应用于核幔边界附近和地幔上下方向附近结构的深地幔散射成像，以更好地描述这些行星特征的热力学和动力学性质。这项整体研究工作将使PI和两名研究生参与震源和地球结构研究问题，使用定量分析震源产生的各种波型。我们希望充分表征地震辐射的深度依赖性，并评估地震摇晃危险性的含义。我们预计在表征与地表附近和核幔边界附近的地球主要边界层相关的重要动力学过程方面将取得持续进展，利用这些信息来了解地球中的热流以及驱动地表地震和火山的动力学过程。

The UCSC seismological research program supervised by Professor Thorne Lay uses global broadband digital seismic data (as well as high-rate GPS data and tsunami recordings) to address fundamental questions about earth structure and earthquake rupture processes. Quantitative analysis of recorded wave-fields generated by earthquakes will be used to address the following fundamental questions: (1) joint inversions of high-rate GPS data, broadband seismic body waves and surface waves, and tsunami observations will be undertaken for recent huge earthquakes in Chile, Mentawai, and off-Sumatra, for the purpose of understanding how the ruptures grew and how the faults slipped in each case; (2) spectral analysis of earthquakes on and near plate boundary megathrust faults will be conducted using strong-motion and teleseismic recordings of seismic wave vibrations to further develop and test a recently introduced model of depth-dependent variations in seismic radiation from megathrust faults; (3) stacking and migration of seismograms from deep focus earthquakes will be performed to develop images of upper mantle reflectivity and heterogeneity spectrum in the vicinity of subduction zones; and (4) new stacking and migration approaches will be applied to imaging of deep mantle scattering from structures near the core-mantle boundary and near mantle down-wellings and up-wellings to better characterize the thermal and dynamical nature of these planetary features. This overall research effort will engage the PI and two graduate students in both earthquake source and earth structure research problems using quantitative analysis of various wave types generated by earthquake sources. We hope to fully characterize the depth-dependence of seismic radiation from earthquakes, and to evaluate the implications for earthquake shaking hazard. We anticipate sustaining progress in characterizing important dynamical processes associated with the Earth's major boundary layers near the surface and near the core-mantle boundary, drawing upon this information to understand the heat flow in the Earth and the dynamical processes that drive earthquakes and volcanoes at the surface.