The Ulakhan fault surface rupture and the seismicity of the Okhotsk–North America plate boundary

<p>New field work, combined with analysis of high-resolution aerial photographs, digital elevation models, and satellite imagery, has identified an active fault that is traceable for <span class="inline-formula">∼90</span> km across the Seymchan Basin and is pa...

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Main Authors:	D. Hindle, B. Sedov, S. Lindauer, K. Mackey
Format:	Article
Language:	English
Published:	Copernicus Publications 2019-04-01
Series:	Solid Earth
Online Access:	https://www.solid-earth.net/10/561/2019/se-10-561-2019.pdf

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spelling	doaj-b853c4d217eb4a82b4f6de442cf1e2322020-11-25T01:22:54ZengCopernicus PublicationsSolid Earth1869-95101869-95292019-04-011056158010.5194/se-10-561-2019The Ulakhan fault surface rupture and the seismicity of the Okhotsk–North America plate boundaryD. Hindle0B. Sedov1S. Lindauer2K. Mackey3Georg-August-Universität Göttingen, Goldschmidtstr. 3, 37077 Göttingen, GermanyUniversity of Magadan, Geological Institute, Magadan, RussiaKlaus-Tschira-Archäeometrie-Zentrum, 68159 Mannheim, GermanyMichigan State University, Dept. of Geological Sciences, East Lansing, Michigan, USA<p>New field work, combined with analysis of high-resolution aerial photographs, digital elevation models, and satellite imagery, has identified an active fault that is traceable for <span class="inline-formula">∼90</span> km across the Seymchan Basin and is part of the Ulakhan fault system, which is believed to form the Okhotsk–North America plate boundary. Age dating of alluvial fan sediments in a channel system that is disturbed by fault activity suggests the current scarp is a result of a series of large earthquakes (<span class="inline-formula">≥<i>M</i><sub>w</sub> 7.5</span>) that have occurred since <span class="inline-formula">11.6±2.7</span> ka. A possible channel feature offset by <span class="inline-formula">62±4</span> m associated with these sediments yields a slip rate of <span class="inline-formula">5.3±1.3</span> mm yr<span class="inline-formula"><sup>−1</sup></span>, in broad agreement with rates suggested from global plate tectonics. Our results clearly identify the Ulakhan fault as the Okhotsk–North America plate boundary and show that tectonic strain release is strongly concentrated on the boundaries of Okhotsk. In light of our results, the likelihood of recurrence of <span class="inline-formula"><i>M</i><sub>w</sub> 7.5</span> earthquakes is high, suggesting a previously underestimated seismic hazard across the region.</p>https://www.solid-earth.net/10/561/2019/se-10-561-2019.pdf
collection	DOAJ
language	English
format	Article
sources	DOAJ
author	D. Hindle B. Sedov S. Lindauer K. Mackey
spellingShingle	D. Hindle B. Sedov S. Lindauer K. Mackey The Ulakhan fault surface rupture and the seismicity of the Okhotsk–North America plate boundary Solid Earth
author_facet	D. Hindle B. Sedov S. Lindauer K. Mackey
author_sort	D. Hindle
title	The Ulakhan fault surface rupture and the seismicity of the Okhotsk–North America plate boundary
title_short	The Ulakhan fault surface rupture and the seismicity of the Okhotsk–North America plate boundary
title_full	The Ulakhan fault surface rupture and the seismicity of the Okhotsk–North America plate boundary
title_fullStr	The Ulakhan fault surface rupture and the seismicity of the Okhotsk–North America plate boundary
title_full_unstemmed	The Ulakhan fault surface rupture and the seismicity of the Okhotsk–North America plate boundary
title_sort	ulakhan fault surface rupture and the seismicity of the okhotsk–north america plate boundary
publisher	Copernicus Publications
series	Solid Earth
issn	1869-9510 1869-9529
publishDate	2019-04-01
description	<p>New field work, combined with analysis of high-resolution aerial photographs, digital elevation models, and satellite imagery, has identified an active fault that is traceable for <span class="inline-formula">∼90</span> km across the Seymchan Basin and is part of the Ulakhan fault system, which is believed to form the Okhotsk–North America plate boundary. Age dating of alluvial fan sediments in a channel system that is disturbed by fault activity suggests the current scarp is a result of a series of large earthquakes (<span class="inline-formula">≥<i>M</i><sub>w</sub> 7.5</span>) that have occurred since <span class="inline-formula">11.6±2.7</span> ka. A possible channel feature offset by <span class="inline-formula">62±4</span> m associated with these sediments yields a slip rate of <span class="inline-formula">5.3±1.3</span> mm yr<span class="inline-formula"><sup>−1</sup></span>, in broad agreement with rates suggested from global plate tectonics. Our results clearly identify the Ulakhan fault as the Okhotsk–North America plate boundary and show that tectonic strain release is strongly concentrated on the boundaries of Okhotsk. In light of our results, the likelihood of recurrence of <span class="inline-formula"><i>M</i><sub>w</sub> 7.5</span> earthquakes is high, suggesting a previously underestimated seismic hazard across the region.</p>
url	https://www.solid-earth.net/10/561/2019/se-10-561-2019.pdf
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The Ulakhan fault surface rupture and the seismicity of the Okhotsk–North America plate boundary

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