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内的主要但未知的断层带。 Nenana 盆地位于阿拉斯加-阿留申海沟以北 700 公里处，是一个深 7 公里的活动沉积盆地，与 200 公里长的 Minto Flats 地震带对齐。该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区域。两次深层事件包括 2012 年触发的 24 秒成核期地震，以及 1995 年发生的 6.0 级地震，该地震使一小部分断层带破裂并强烈震动该地区。三维断层带结构以及活动沉积盆地与次盆地断层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。塔纳纳河为针对断层带的 12 个战略站部署提供了通道。当地地震的地震波形将用于制定准确的地震位置目录。局部事件的新矩张量目录将表征断层的类型。通过断裂带内地震的地震波场模拟，探讨断裂复杂性、地震破裂、盆地结构对区域地震波场的影响。地震数据建模将有助于确定异常深部地壳地震活动是否与上覆盆地形成、下伏板片驱动过程或横向驱动过程有关。本次实验期间收集的地震波形将是该活动构造区域首次记录的地震波形，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。明托平原断层带的表征将为阿拉斯加中部盆地形成和变形的竞争构造模型提供基本约束。该项目包含大量教育内容，包括来自内纳纳的高中生以及本科生和研究生。实地教学模块、课堂教学模块以及每年费尔班克斯科学展览实地考察将使尼纳纳高中生了解阿拉斯加的地震科学和活动构造。

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.