2012 IRIS Workshop
Search for Tectonic Tremor in Central Chile Following the February 2010 Maule Earthquake
Carl Ulberg: Ken Creager: Justin Sweet: Aaron Wech:
Data from the CHAMP deployment are examined for evidence of tectonic tremor following the 2010 Maule earthquake in Chile. Left: Location of events detected with the waveform envelope cross-correlation method (Wech and Creager, 2008) in the first two weeks of August compared with seismicity recorded by the USGS from March to September of 2010. Stations are gray triangles. Right: Waveforms such as these exhibiting tremor-like characteristics are examined.
Full-resolution graphics file in original format: 0116.png
Seismic data are examined from central Chile, from March to late September of 2010, following the February 27, 2010 M8.8 Maule earthquake. Data from 58 stations of the CHAMP deployment are bandpass filtered at frequencies between 1.5- and 5.5-Hz, and envelopes are calculated. We search for evidence of tectonic tremor, using a variety of methods. There are a number of aftershocks recorded in the data, and care is taken to account for these. In particular, periods of increased background noise are examined closely. Initial results from using the waveform envelope cross-correlation method (Wech and Creager, 2008) show thousands of event locations at latitudes and longitudes corresponding to the upper ~40-km of the subducting slab. Roughly half of the 5-minute windows examined yield locations, many or all of which are likely from earthquakes. The event distribution is very similar to the distribution of seismicity between March and September of 2010 as determined by the USGS. However, there are some event locations at regions down-dip of the locked portion of the plate interface which will be examined more closely.
Acknoweldgements: Data come from the CHAMP deployment and funding to calculate the envelopes is provided by an IRIS Data Management System sub-award.
Keywords: chile, tremor, slow_slip
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