Collaborative Research: Patterns of Serial Fault Rupture in Taiwan

KERRY SIEHEAR-0208505本项目对台湾两个活动断裂系统--车龙铺断裂和纵谷断裂进行了研究，这两个断裂在1999年和1951年的大地震中破裂，以研究重复断裂行为和破裂模式的时间变异性。车龙堡断裂和纵谷断裂的破裂时间序列的获取为系列断层破裂和断层相互作用的物理模型提供了约束。这些结果与地震危险性分析有关，通过考虑导致地震的物理过程，包括相邻断层破裂的相互作用，先前断裂对断层的影响，地质构造和断层几何形状对破裂终止的影响以及抗震与地震行为的关系。车龙铺断裂的古地震研究正在刻画其地震重复和位移历史。例如，如果像1999年那样的地震重现的频率要低得多，那么同一纬度的其他建筑将在应变缓解方面发挥重要作用。这些调查的结果对理解个别断层和造山的应变解除的物理过程具有重要意义。终端成员假说，从无模式或随机重复到高度聚集的行为，正在使用沿着车龙堡和邻近的反断层获得的地震时间历史进行测试。该项目还表征了纵向山谷断层的活动断层。为选定的几个沿海海洋梯田确定海岸线角度的高程，限制了纵向山谷沿线的千禧年增长率。利用地质填图和测年技术，可以得到纵向河谷和东部沿海地区之间的时间平均隆升速率。

Kerry SiehEAR-0208505This project undertakes studies of two active fault systems in Taiwan, the Chelungpu and Longitudinal Valley faults, which ruptured during large earthquakes in 1999 and 1951, in order to address recurrence fault behavior and the temporal variability of rupture modes. Acquisition of rupture time series on the Chelungpu and Longitudinal Valley faults provide constraints on physical models of serial fault rupture and fault interactions. These results bear on seismic hazard analysis, by considering the physical processes that lead to an earthquake, including the interaction of adjacent fault ruptures, the effect of prior ruptures on a fault, the influence of geologic structure and fault geometry on rupture termination and aseismic versus seismic behavior.Paleoseismic studies along the Chelungpu fault are characterizing its earthquake recurrence and displacement history. For example, if the recurrence of 1999-like earthquakes is far less frequent, then other structures at the same latitude would have to play an important role in strain relief. Results from these investigations have implications for understanding the physical processes of strain relief on individual faults and of mountain building. End-member hypotheses, ranging from unpatterned or random recurrence to highly clustered behavior, are being tested using earthquake time histories obtained along the Chelungpu and adjacent reverse faults.The project also characterizes the active faults of the Longitudinal Valley faults. Determining the elevations of shoreline angles for a select handful of coastal marine terraces is constraining the millennial rates along the Longitudinal Valley. Geologic mapping and dating of the fluvial terraces along Shiouguluan River are providing the time-averaged uplift rates between the Longitudinal Valley and the eastern coastal region.