Paleoseismological Investigations on the Kamchatka Peninsula, Russia

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The Pacific coast of the southern Kamchatka Peninsula offers a unique opportunity to study in detail the history of a subduction zone over several thousand years. The long-term goal of this investigation is to examine the possible segmentation and episodicity of seismicity associated with this subduction zone. Specifically, this study will use frequency of tsunami deposits as a proxy for seismic activity. Because tephra (volcanic ash layers) are abundantly preserved in Kamchatka, coastal zone stratigraphy, correlation and age dating of tsunami deposits are eminently feasible. Holocene shoreline history is recorded in modern and uplifted coastal terraces, which can also be dated and correlated using tephrostratigraphy. The Kamchatka coast has experienced little occupation or human alteration, so that deposits are well preserved and rarely disturbed. This award supports a combined U. S.-Russian team to conduct detailed studies near the northern end of the subduction zone (Cape Kamchatskiy). This pilot study involves an extended field program of mapping, trenching, and stratigraphic description; samples of ash layers and tsunami deposits will then be analyzed chemically and granulometrically. To improve already existing tephrochronology, radiocarbon dates will be acquired from associated peat layers. Composite sections can then be constructed and analyzed statistically to examine the long-term history of tsunamigenic events in this region. In addition, this work will help reconstruct a detailed, short-term history of tsunamis associated with the Kamchatka subduction zone.