The SIerras pampeanas Experiment using a Multicomponent BRoadband Array (SIEMBRA) was designated to examine flat slab subduction, crustal and upper mantle structure, and crustal deformation of west-central Argentina (~30-32º S). SIEMBRA, which in Spanish means crop (like if we were “planting” instruments on the ground) is a follow-up to the CHile ARgentina Geophysical Experiment (CHARGE) that took place between 2000 and 2002 and looked at slab and mantle structure, the transition from normal to flat slab subduction, and earthquake generation. SIEMBRA focuses in greater detail in the area above the flat slab subduction beneath the San Juan and La Rioja provinces. This region is particularly interesting since is considered a modern analog for the western U.S. Laramide flat subduction.
SIEMBRA is NSF-funded project that involves faculty and students from the University of Arizona, the National University of San Juan, and INPRES. International agreements between these institutions have been established or updated for the development of this project.
Several large damaging earthquakes have occurred in central-west Argentina during the last century such as the San Juan earthquakes of 1944 (magnitude 7.0), 1952 (magnitude 6.8), and 1977 (magnitude 7.5), and the Mendoza earthquake of 1985 (magnitude 5.9). The 1944 earthquake devastated the city of San Juan and had a death toll of at least 5,000 people making this event the largest natural disaster in the history of Argentina.
Map of historical earthquakes in the Cuyo region