Collaborative Research: Seismic Failure Processes of Intersecting Intraplate Faults Using Microearthquake Clusters

9614448谢这项研究是哥伦比亚大学和德克萨斯农工大学通过微震丛集特征对美国中部新马德里地震带的破坏过程进行的合作研究。早期的分析将扩展到整个NMSZ的聚集事件。大多数星团位于中心节段的拐点附近，或该节段与其他主要节段的交界处附近。空间/时间星团发生在4到9公里的深度范围内，既显示了走向机制，也显示了反向滑动震源机制，并位于节段交界处和扭结附近或远离节段交界处。其目的是为集群提供最好的物理模型，并进一步深入了解1)较大断裂的静态应力降与震源深度、震源机制和靠近或远离交界处的位置的关系，2)NMSZ主要断裂段之间的相互作用模式，如沿相交断裂段的地震或非地震预滑触发破裂，以及3)流体参与在断裂过程中的作用。这项研究是国家减少地震灾害计划的一部分。***

9614448 Xie This research is for collaborative research between Columbia and Texas A&M Universities on the failure processes in the New Madrid Seismic Zone (NMSZ) of the Central U.S. through characterization of microearthquake clustering. Earlier analysis is to be extended to clustered events throughout the NMSZ. Most clusters are located near the kink in the central segment, or near the junctions of that segment with other major segments. The spatial/temporal clusters occur over a range of depths of 4 to 9 km, display both strike and reverse slip focal mechanisms, and are located both near and away from the segment junctions and the kink. The goal is to provide the best physical model for the clustering and give additional insight into 1) the relation of the static stress drops of the larger ruptures to focal depths, focal mechanisms, and locations near or away from the junctions, 2) the mode of interactions among major fault segments in the NMSZ, such as triggering of ruptures by seismic or aseismic preslip along intersecting fault segments, and 3) the role of fluid involvement in faulting processes. This research is a component of the National Earthquake Hazard Reduction Program. ***