Seismicity in the Central Andean Southern Puna Antofalla Gap: New Results from the Southern PUNA Passive Seismic Array

CHEN, C., MAHLBURG KAY, S., SANDVOL, E.A., BROWN, L.D., ISACKS, B.L., HEIT, B., COIRA, B. AND YUAN, X.

San Francisco, California

Congreso; American Geophysical Union, Fall Meeting 2009; 2009

American Geophysical Union

Preliminary locations for earthquakes recorded by the Central Andean southern PUNA seismic array, which operated between December 2007 and November 2009, show widespread low magnitude seismicity in the region of the well known teleseismic gap between 25°S and 28°S, which is here referred to as the Antofalla teleseismic gap. The southern PUNA experiment, which is a collaboration of Argentine, Chilean, German and U.S. scientists, consisted of 75 stations deployed over an area bounded by 25°S to 28°S and 70°W to 65°W. The US component of the network included 23 broad band and 22 short period seismometers; the German component included 9 broadband and 21 short period seismometers. Previous regional geophysical studies (e.g. Cahill and Isacks 1992) showed a relative lack of crustal earthquakes as well as few large events below 100 km in the Wadati-Benioff zone between 25°S and 28°S. The southern Puna Antofalla gap in teleseismicity is also evident in the current PDE global catalog. Nevertheless, new data from the PUNA network show substantial low magnitude seismic activity (generally