Q-values and Attenuation of the Shallow Crust Under Uturuncu Volcano, Bolivia
Uturuncu Volcano, located in the Altiplano-Puna region of the central Andes, near the border of Bolivia and Chile, has been shown to be inflating at a rate of 1-2 cm/yr over an area that is about 70 km wide. The PLUTONS project deployed 28 broadband seismometers around Uturuncu from April 2009 to October 2012. Several thousand shallow (depth < 20 km) local earthquakes were recorded. Attenuation of seismic waves along travel paths for these local crustal earthquakes can be measured by calculating Q-values, which we have performed using the method of single station spectral ratios by Frankel (1982). Large scatter in the Q-values for various distances and travel times appear to be a function of variations in source depth, focal mechanism, and back azimuth. Preliminary Q-values were calculated for azimuths in 30° increments in sectors around each station. Estimates for Q range from about 60 to 700, with many showing a low Q in the direction of the summit from each station. This suggests that the volcanic pile is more highly attenuating than the surrounding crust.
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Citation / Publisher Attribution
Presented at the AGU Fall Meeting on December 11, 2017 in New Orleans, LA
Scholar Commons Citation
McFarlin, Heather L.; McNutt, Stephen R.; and Thompson, Glenn, "Q-values and Attenuation of the Shallow Crust Under Uturuncu Volcano, Bolivia" (2017). School of Geosciences Faculty and Staff Publications. 2185.