PULSE and CAUGHT: Seismology in the High Andes

A map showing the PULSE (red triangles) and CAUGHT (blue triangles) stations. Contours at 50-km (30-mile) intervals show significant variation in the dip of the subducting Nazca Plate. Shaded topography shows the significant variation in elevation across the region. (from Hayes et al, 2012)

Two complementary experiments, Peru Lithosphere and Slab Experiment (PULSE) and Central Andes Uplift and Geodynamics of High Topography (CAUGHT), were deployed in late 2010 to examine the processes of ocean-continent subduction and mountain building in the Central Andes of Peru and Bolivia. These stations add to data collected in 1994-1995 by the Broadband Andean Joint (BANJO) experiment and Seismic Exploration of the Deep Altiplano (SEDA) experiment, which pioneered PASSCAL-supported portable seismographic deployments in South America.

Deployed across southern Peru, PULSE investigates the causes and effects of the flat-slab subduction of the Nazca Plate beneath South America. Flat-slab subduction is the nearly horizontal subduction of an oceanic plate, which has led to its unusually shallow depth beneath much of Peru when compared to the adjacent regions. To the south, where volcanism in the Andes resumes, the slab steepens below the Altiplano, the world’s second highest plain.. Deployed across the Altiplano of Peru and Bolivia, the CAUGHT stations are part of an interdisciplinary project aimed at exploring the geodynamic processes that have formed this high plateau.

The seismometers deployed in these experiments will operate continuously for 2-3 years to record local earthquakes as well as large earthquakes from around the world. These data will be used to image and understand the physical characteristics of flat-slab subduction and to map the structure of the Altiplano. Fieldwork and subsequent analyses from these experiments jointly leveraged the expertise of the principal investigators, field teams, and local collaborators, allowing the projects to focus on maximizing science returns.

Websites:

Principal Investigators George Zandt and Susan Beck (University of Arizona), their graduate students and field team, and Bolivian hosts following the installation of a CAUGHT seismometer on their land in the Andes at 13,000 feet elevation. University of North Carolina student Abhash Kumar constructs a PULSE station. The seismometers and dataloggers for the CAUGHT experiment are being tested in the host country before being transported to the field.

 

 

 

 

 

 

 

 

 

 

 

References:
Hayes, G.P., D.J. Wald, and R.L. Johnson (2012), Slab1.0: A three-dimensional model of global subduction zone geometries, J. Geophys. Res., 117, B01302, doi:10.1029/2011JB008524.

Principal Investigators and Institutions:
Susan Beck (University of Arizona, CAUGHT and PULSE)
Maureen Long (Yale University, PULSE)
Lara Wagner (University of North Carolina, CAUGHT and PULSE)
George Zandt (University of Arizona, CAUGHT)

Field Dates:
CAUGHT: November 2010 - August 2012
PULSE: October 2010 - May 2013 (in progress)

Equipment:
PULSE: 40 broadband seismometers
CAUGHT: 50 broadband seismometers

Funding Source:
National Science Foundation Earth Sciences - Geophysics: PULSE Award
National Science Foundation Earth Sciences - Continental Dynamics: CAUGHT Award