The Central Andean Altiplano‐Puna magma body

Receiver function analysis of 14 teleseismic events recorded by 6 temporary PASSCAL broadband stations within the Altiplano‐Puna volcanic complex (APVC) shows a consistent ∼2 s negative‐polarity P ‐to‐ S conversion for all stations for all available azimuths. Forward modeling of the largest amplitudes suggests that this conversion is produced by the top of a very low velocity zone at a depth of ∼19 km, with a Vs <0.5 km/s and a thickness of 750–810 m. We interpret the characteristics of the low‐velocity zone (low Vs , areal extent, and flatness) to be consistent with a sill‐like magma body. On the basis of additional data from the German ANCORP experiment, the Altiplano‐Puna magma body appears to underlie much of the APVC, and it may therefore be the largest known active continental crustal magma body.