Collaborative Research: Simultaneous Imaging of the Megathrust and Volcanic Systems in the Aleutian Islands Using Hybrid Mini Seismic Arrays

University Of California-Riverside, Riverside CA

Investigators

Abstract

The Alaska-Aleutian subduction zone is one of the most active areas in the world, in terms of its seismic and volcanic activity. The megathrust experiences large damaging fast (normal) earthquakes, slow earthquakes and associated tectonic tremor revealing a wide spectrum of slip behavior. The volcanoes show a complex blend of seismicity, from volcanic tremor to deep long-period (DLP) events. Many of these tectonic and volcanic natural systems remain relatively unexplored because of the challenging logistics leading to poor instrumentation. We propose to install 4 hybrid mini seismic arrays and 6 stand-alone seismic stations on Unalaska and Akutan Islands, to capture this rich variety of seismic activity, both tectonic and volcanic, and image earth structure in high resolution. The experiment is designed such that it simultaneously images multiple sources, thereby illuminating both megathrust and volcanic systems at the same time. Deployment of mini arrays is logistically convenient in this challenging environment compared to conventional network-style deployments with similar number of stations maximizing scientific gain with relatively low cost. This study will be an important step forward in our understanding of the complex volcanic and tectonic systems and their interplay in Alaska-Aleutian subduction complex. This intertwined natural system will be investigated by combining novel array techniques to image multiple sources with an augmented conventional seismic network. This study will examine a wide spectrum of fault slip dynamics, volcanic plumbing system and earth structure in this area. It will not only enrich our knowledge of the subduction system in this area but also might be extrapolated to other areas like Cascadia that are not so productive seismically. The Alaska-Aleutian subduction zone has witnessed a number of large damaging earthquakes in instrumental history. The Unalaska-Akutan area is located near the eastern edge of the 1957 M8.6 megathrust rupture zone. The proposed study will help better understand the dynamics of the subduction fault, and therefore aid in seismic hazard analyses. In addition, Akutan and Makushin are among the most frequently active volcanoes in the United States and are defined as ?very high threat?. They both pose threat to nearby population centers. This study will help us image and understand the volcanic plumbing systems leading to improved monitoring of precursory phenomena. Moreover, this project will help advance the career of an early-career faculty member, post doctoral researchers, and graduate students, and foster collaboration between educational and government institutions.