CAREER: Intraplate tectonics and deep crustal faulting in Rural Alaska

该项目将地震建模和地震波场模拟应用于新的地震数据采集，以表征北美最活跃的板内区域之一的主要但未知的断裂带。Nenana盆地位于阿拉斯加-阿留申海沟以北700公里处，是一个7公里深的活跃沉积盆地，与200公里长的Minto Flats地震带对齐。在阿拉斯加中部，地震带包含了最集中的深层（15公里）地壳地震活动。两个深层事件包括2012年引发的24秒成核阶段地震，以及1995年发生的6.0兆瓦地震，该地震使断裂带的一小部分破裂，并强烈震动了该地区。三维断裂带结构以及活动沉积盆地与次盆地断裂之间的关系尚不清楚，部分原因是在这个偏远地区从未部署过地震台站。塔纳纳河为针对断裂带的12个战略站点部署提供了通道。当地地震的地震波将被用来编制准确地震位置的目录。一个新的局部事件矩张量目录将描述断裂的样式。通过对断裂带内地震的地震波场模拟，探讨断层复杂性、地震破裂和盆地构造对区域地震波场的影响。地震数据的建模将有助于确定异常的深部地壳地震活动是否与上覆盆地形成、下伏板块驱动过程或横向驱动过程有关。本次实验收集到的地震波形将是首次在这一活跃的构造区域记录下来，它们将为未来阿拉斯加中部的地球物理研究提供宝贵的资源。Minto Flats断裂带的特征将为阿拉斯加中部盆地形成和变形的竞争性构造模型提供基本约束。该项目有大量的教育组成部分，包括来自Nenana的高中生，以及本科生和研究生。实地教学模块，课堂教学模块，以及每年到费尔班克斯参观科学展览的实地考察，将使南纳纳高中的学生参与地震科学和阿拉斯加的活动构造。

This project applies earthquake modeling and seismic wavefield simulations to a new seismic data acquisition in order to characterize a major, yet unknown, fault zone within one of the most active intraplate regions of North America. Located 700 km north of the Alaska-Aleutian trench, the Nenana basin is a 7 km deep, active sedimentary basin aligned with the 200 km long Minto Flats seismic zone. The seismic zone contains the highest concentration of deep (15 km) crustal seismicity in central Alaska. Two deep events include a 2012 triggered earthquake with a 24 s nucleation phase, and also a 1995 Mw 6.0 earthquake that ruptured a small portion of the fault zone and strongly shook the region. The three-dimensional fault zone structure and the relationship between the active sedimentary basin and the sub-basin faulting are unknown, in part because no seismic station has ever been deployed in this remote region. The Tanana river provides access for a strategic 12-station deployment targeting the fault zone. Seismic waveforms from local earthquakes will be used to develop a catalog of accurate earthquake locations. A new moment tensor catalog for local events will characterize the style of faulting. Seismic wavefield simulations of earthquakes within the fault zone will be used to explore the influences of fault complexity, earthquake ruptures, and basin structure on the regional seismic wavefield. Modeling of the seismic data will help determine whether the anomalously deep crustal seismicity is related to overlying basin formation, to underlying slab-driven processes, or to laterally driven processes.The seismic waveforms collected during this experiment will be the first ever recorded in this active tectonic region, and they will provide a valuable resource for future geophysical studies in central Alaska. Characterization of the Minto Flats fault zone will provide fundamental constraints on the competing tectonic models for basin formation and deformation within central Alaska. The project has a substantial education component that includes high school students from Nenana, as well as undergraduate and graduate students. Field-based teaching modules, classroom-based teaching modules, and annual field trips to science exhibits in Fairbanks will engage Nenana high school students in earthquake science and active tectonics of Alaska.