Structural and Seismologic Investigation of Blind-thrust Earthquake Segmentation, San Joaquin Basin, California

通过对1982年新伊德里亚（Mw=5.4）、1983年科林加（Mw=6.5）和1985年凯特尔曼山（Mw=6.1）地震的综合地质和地震学分析，正在研究盲冲地震分段的性质，这些地震发生在加州中部的圣华金盆地西部。这些地震发生在新伊德里亚、科林加和凯特尔曼山的背斜之下，这些背斜形成了一个向南延伸到洛斯特山的雁行结构系统。同震隆起和地下研究的模式令人信服地表明，这些结构是断层相关的褶皱，发展在下面的盲冲系统的运动。这三个地震的破裂区域的限制是由这个褶皱系统的不同的雁行偏移定义的，这被认为是覆盖在下面的盲冲断层的几何段边界。褶皱具有良好的地表暴露，地下结构由丰富的工业地震反射和测井数据确定。因此，这方面提出了一个很好的机会，研究过程中的盲冲地震分割，深入了解，可以帮助评估地震灾害在其他地区的活跃thushing.The的几何形状和运动学的失落山- Kettleman山-科林加褶皱和逆冲断层链的特点是利用地震反射剖面，井控制，地表地质，遥感图像，并精确地重新定位地震活动。该分析记录了撕裂（走滑）断层、侧向斜坡和地震段边界处其他类型的断层联系的发生情况。这些边界的断层几何形状的见解将转化为帮助开发一个更好的方法来定义潜在的段边界上的其他盲冲系统，这往往决定了地震的位置和震级，两个关键参数在概率地震危险性评估。此外，这些详细的结构模型可以提供一个有据可查的情况下，数值研究的动态破裂传播和余震分布在盲冲事件。此外，这些调查将提供一个地震构造模型，解决故障活动的速率和时间变化，这可以比较到更多的区域测量，如空间大地测量和地震活动的邻近断层系统，包括圣安德烈亚斯。

The nature of blind-thrust earthquake segmentation is being examined through integrated geologic and seismologic analyses of the 1982 New Idria (Mw=5.4), 1983 Coalinga (Mw=6.5), and 1985 Kettleman Hills (Mw=6.1) earthquakes, which occurred in the western San Joaquin basin of central California. These earthquakes occurred beneath the New Idria, Coalinga, and Kettleman Hills anticlines, which form an en echelon system of structures that extend south to Lost Hills. Patterns of coseismic uplift and subsurface studies have demonstrated convincingly that these structures are fault-related folds that develop in response to motions on the underlying blind-thrust system. The limits of the rupture areas for the three earthquakes are defined by the distinct en echelon offsets of this fold system, which are thought to overlie geometric segment boundaries in the underlying blind-thrust fault. The folds have excellent surface exposures, and the subsurface structure is defined by a wealth of industry seismic reflection and well log data. Thus, this area presents an excellent opportunity to study processes of blind-thrust earthquake segmentation, insights into which can help to assess earthquake hazards in other regions of active thrusting.The geometry and kinematics of the Lost Hills - Kettleman Hills - Coalinga fold and thrust chain is characterized utilizing seismic reflection profiles, well control, surface geology, remote sensing imagery, and precisely relocated seismicity. The analysis is documenting the occurrence of tear (strike-slip) faults, lateral ramps, and other types of fault linkages at the earthquake segment boundaries. Insights into the fault geometries of these boundaries will translate into helping to develop a better methodology for defining potential segment boundaries on other blind-thrust systems, which often dictate the locations and magnitudes of earthquakes, two key parameters in probabilistic seismic hazard assessment. Moreover, these detailed structural models can provide a well-documented case study for numerical investigations of dynamic rupture propagation and aftershock distribution during blind-thrust events. Additionally, these investigations will provide a seismotectonic model that addresses the rates and temporal variability of fault activity, which can be compared to more regional measurements such as space geodesy and to earthquake activity on adjacent faults systems, including the San Andreas.