Collaborative Research: Paleoseismology and Paleogeodesy of the Sumatran Subduction Zone

EAR-0207690加州大学圣克鲁斯分校继续对苏门答腊岛俯冲带的古地震学和古地理进行研究，以确定断层破裂之间可能存在的周期规律性，断层上滑动模式的重复性，地质构造对断层破裂的影响，以及地震/地震耦合随时间的变化。这项研究的核心是使用对海平面变化敏感的珊瑚头(Porite和其他种类)，不确定度为几厘米。年生长带给出了相对误差为几年的时间序列，U-Th测年给出了误差为十年的日期。与地震有关的垂直形变的大小(古地震学)和两次地震之间的形变(古地形学)正在从这些数据中确定。正在对结果进行模拟，并使用历史地震(来自各种来源的地震图)来确定分段边界是否影响了历史破裂的尺寸。该项目的具体目标是：(1)更好地描述1681年、1797年和1833年地震的震源参数；(2)确定这些事件的南部界限；(3)将记录追溯到14世纪；(4)确定1861年和1907年地震的震源特征；(5)建立苏门答腊岛断裂大地震的历史地震图；(6)描述1861年、1797年和1833年地区的无地震应变事件。

EAR-0207690University of California-Santa CruzThis study continues investigations of the paleoseismology and paleogeodesy of the Sumatran subduction zone in order to determine possible regularity of periods between fault ruptures, repeatability of pattern of slip on faults, influence of geologic structure on fault rupture, and variation of seismic/aseismic coupling with time. The centerpiece of the study is the use of coral heads (Porites and other genera) that are sensitive to sea level changes with uncertainties of a few centimeters. Annual growth bands give time-series with relative errors of a few years and U-Th dating of the heads gives dates with errors of a decade. The magnitude of vertical deformation associated with earthquakes (paleoseismology) and deformation in intervals between earthquakes (paleogeodesy) are being determined from these data. Results are being modeled and historical earthquakes (seismograms from a variety of sources) are being used to determine if segment boundaries influenced dimensions of historical ruptures. The specific goals of this project are to: (1) better characterize source parameters of 1681, 1797, and 1833 events; (2) determine southern limit of these events; (3) extend record back to 14th century; (4) determine source characteristics of 1861 and 1907 quakes; (5) model historical seismograms of large quakes on Sumatran fault; (6) characterize aseismic strain events in 1861, 1797, and 1833 regions.