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...
| Main Authors: | , , , |
|---|---|
| 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 |
| Summary: | <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> |
|---|---|
| ISSN: | 1869-9510 1869-9529 |