Grzegorz Kwiatek
Seth C. Moran
Rebecca M. Harrington
2015
<p><span>We analyze a group of 6073 low-frequency earthquakes recorded during a week-long temporary deployment of broadband seismometers at distances of less than 3 km from the crater at Mount St. Helens in September of 2006. We estimate the seismic moment (</span><i>M</i><span>0</span><span>) and spectral corner frequency (</span><i>f</i><span>0</span><span>) using a spectral ratio approach for events with a high signal-to-noise (SNR) ratio that have a cross-correlation coefficient of 0.8 or greater with at least five other events. A cluster analysis of cross-correlation values indicates that the group of 421 events meeting the SNR and cross-correlation criteria forms eight event families that exhibit largely self-similar scaling. We estimate the </span><i>M</i><span>0</span><span> and </span><i>f</i><span>0</span><span> values of the 421 events and calculate their static stress drop and scaled energy (</span><i>E</i><span><i>R</i></span><span>/</span><i>M</i><span>0</span><span>) values. The estimated values suggest self-similar scaling within families, as well as between five of eight families (i.e., </span><span class="math-equation-construct" data-equation-construct="true"><span class="math-equation-image" data-equation-image="true"><img class="inlineGraphic" src="http://api.onlinelibrary.wiley.com/asset/v1/doi/10.1002%2F2014JB011744/asset/equation%2Fjgrb51149-math-0001.png?l=SkaBT8QEx2qAil3ITBtkuHTOQ1pnqowGQTmpw5QHnx2U2cn3oXAM090hrHXYlyZSX7%2Bmk1m%2BpFCe%0AAIvE%2FSocLg%3D%3D" alt="inline image" /></span></span><span> and </span><span class="math-equation-construct" data-equation-construct="true"><span class="math-equation-image" data-equation-image="true"><img class="inlineGraphic" src="http://api.onlinelibrary.wiley.com/asset/v1/doi/10.1002%2F2014JB011744/asset/equation%2Fjgrb51149-math-0002.png?l=SkaBT8QEx2qAil3ITBtkuHTOQ1pnqowGQTmpw5QHnx2U2cn3oXAM090hrHXYlyZSlKraTIzJaq1Q%0ASI5N7VQPag%3D%3D" alt="inline image" /></span></span><span> constant). We speculate that differences in scaled energy values for the two families with variable scaling may result from a lack of resolution in the velocity model. The observation of self-similar scaling is the first of its kind for such a large group of low-frequency volcanic tectonic events occurring during a single active dome extrusion eruption.</span></p>
application/pdf
10.1002/2014JB011744
en
American Geophysical Union
Self-similar rupture implied by scaling properties of volcanic earthquakes occurring during the 2004-2008 eruption of Mount St. Helens, Washington
article