Dr. Mikhail Kogan
Earth Institute Contact: Dr. Mikhail Kogan
Northeast Asia and the Bering Sea remain one of the largest regions for which there is not agreement about the plate configuration. This region has received relatively little attention in the past, perhaps because it is remote and surrounded by other poorly characterized areas, and because researchers were until a decade ago divided by the Iron Curtain. Seismicity patterns and focal mechanisms and the limited existing Global Positioning System (GPS) data demonstrate that at least the southern Bering Sea moves significantly relative to North America, but much of eastern Siberia appears to lie on the North American plate. This proposal is aimed at resolving a fundamental question: does the Bering Plate exist? If not, how large is the mobile sliver of crust in the southern Bering Sea? The answers to these questions are critical for an understanding of the tectonics of NE Asia, Alaska, and the Arctic, and other regions of the world for which this may be an analog. Knowing whether the Bering Plate exists and its rate of motion will give insight into the modes of extrusional continental deformation, and the driving forces that act on microplates.
This study will use a combination of GPS surveys and data from the EarthScope Plate Boundary Observatory (PBO) to resolve these questions. Over the course of a 5-year project (with two years of no funds outside of student support to allow for the earth to move in between surveys), teams from the University of Alaska Fairbanks, Lamont-Doherty Earth Observatory, and Russia will survey 12 new GPS sites in extreme East Siberia (Chukotka and the Koryak Highlands), and repeat observations at sites in 7 existing locations in Alaska. In addition, this study will be able to use data from at least 15-20 PBO sites, several of which will be installed in the second year of the project. Data from these sites, and past data from the region, will be combined into a joint, self-consistent velocity field in which sites will have velocity precision of ~1 mm/yr or better.
This velocity field will provide the means to test the recent proposal that the Bering plate exists and rotates clockwise relative to North America about a pole located in northwestern Chukotka. The data will be sufficient to also test alternatives, in particular, to test whether the Denali fault continues across western Alaska with a high slip rate, and thus separates a westward-translating sliver to the south of it from the rest of the Bering Sea and western Alaska (which may still rotate clockwise, but more slowly than the sliver south of the Denali fault). Clarifying the role of the Denali fault is important for understanding its role in the uplift of the Denali massif and more generally for how slip rates on large strike slip faults change along strike.
Understanding the configuration and kinematics of Earth’s tectonic plates is a fundamental problem in earth sciences. This project will test hypotheses that underlie tectonic models for a significant area at the northwestern corner of the North American plate. The results of this project will have an impact on our understanding of deformation processes in the Aleutian arc, and from central Alaska to eastern Siberia. If either of the particular models described in this proposal successfully passes the test of hard kinematic data, the successful model will have implications for the modes of continental deformation driven by subduction and by the collision/accretion of terranes. Possible analogs proposed for this region include Anatolia and parts of east Asia.
Our results will have an impact on the understanding of the present-day tectonics of a large area of NE Asia and NW North America. This project will improve collaborative ties between US and Russian scientists, provide improved opportunities for several Russian scientists and contribute to the education of a graduate student. The largest impacts outside of earth sciences will be in improving earthquake hazard assessments for the Bering Sea region and in the Russian Far East. These areas are sparsely populated, but the people who live there are critically dependent upon fragile infrastructure that could be severely disrupted by earthquakes.
Cross Cutting Themes:
Hazards and Risk
University of Alaska-Fairbanks, Regional GPS Data Acquisition and Analysis Center