CAREER: Intraplate tectonics and deep crustal faulting in Rural Alaska

该项目将地震模拟和地震波场模拟应用于新的地震数据采集，以确定北美最活跃的板内区之一内的一个主要的、但未知的断裂带的特征。涅纳纳盆地位于阿拉斯加-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地震带一致。地震带是阿拉斯加中部深部(15公里)地壳地震活动最集中的地区。两次深部地震包括2012年触发的24级S地震和1995年的6.0兆瓦地震，后者破裂了断裂带的一小部分，并对该地区进行了强烈震动。三维断裂带结构以及活动沉积盆地和次盆地断裂之间的关系尚不清楚，部分原因是该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个站的战略部署提供了通道。来自当地地震的地震波形将被用来开发准确的地震位置目录。一个新的局部事件的矩张量目录将表征断层的样式。将使用断裂带内地震的地震波场模拟来探索断层复杂性、地震破裂和盆地结构对区域地震波场的影响。对地震数据的模拟将有助于确定地壳异常深部的地震活动是与上覆盆地的形成有关，还是与下伏的板片驱动过程有关，还是与横向驱动过程有关。在这次实验中收集的地震波形将是该活动构造区的第一次记录，它们将为阿拉斯加中部未来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相互竞争的构造模式提供基本约束。该项目有一个重要的教育部分，其中包括来自涅纳纳的高中生以及本科生和研究生。实地教学模块、课堂教学模块和每年一次的费尔班克斯科学展览实地考察将使涅纳纳州的高中生参与阿拉斯加的地震科学和活动构造学。

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.