Uturuncu volcano, located near the borders of Chile and Bolivia in the Central Andes, has been identified as one of two volcanoes in the region with large-scale and active, yet decelerating, inflation. A large low-velocity zone named the Altiplano-Puna magma body (APMB) has been shown to feed magma to Uturuncu and is thought to be a source of the deformation occurring here. The international, multidisciplinary PLUTONS project deployed 28 broadband seismic sensors in a 90 km by 90 km region around and on Uturuncu volcano between April 2010 and October 2012. Over 800 teleseismic receiver functions have been generated and stacked in order to constrain the depths to the top and bottom of this magma body, as well as the depth to the Mohorovičić (Moho) discontinuity. Depths to the top of the magma body are, on average, ∼8 km below mean sea level (bmsl), and it has an average thickness of ∼9 km. This thickness, however, changes directly under Uturuncu to ∼6 km. Depths to the Moho discontinuity are shown to be highly variable over a short distance (less than 100 km), between 39 and 70 km bmsl, with significant upwarping beneath Uturuncu volcano. This study provides a better resolution than previously shown for the depths to major boundaries in the crust beneath Uturuncu and shows the lateral heterogeneity of the top and bottom of the APMB, as well as that of the Moho. In addition, the upwarping in the Moho and the bottom of the APMB coincide with an elongated vertical feature seen in tomography studies of the crust beneath Uturuncu volcano.
Receiver function analyses of Uturuncu volcano, Bolivia and vicinity
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Heather McFarlin, Douglas Christensen, Stephen R. McNutt, Kevin M. Ward, Jamie Ryan, George Zandt, Glenn Thompson; Receiver function analyses of Uturuncu volcano, Bolivia and vicinity. Geosphere doi: https://doi.org/10.1130/GES01560.1
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