hide
Free keywords:
seismology, attenuation tomography, subduction, fluids and melts, central Andes
DDC:
550 - Earth sciences
Abstract:
We present a high resolution 3-D model of P-wave attenuation for the central Andean subduction zone. Data from 1500, mostly intermediate depth (60 - 250 km) earthquakes recorded at three temporary seismic networks covering the forearc, arc, and backarc around 23° S were used for tomographic inversion. The forearc is characterised by uniformly high Qp values, indicating low temperature rocks, in accordance with low surface heat flow values. Continuous regions of low Qp connect earthquake clusters at 100 km and 200 km depth with zones of active wedge, where they induce melting, explain our observations. We propose that low Qp regions indicate source and vertical, as is often implicitely assumed. Instead, sources of fluids are located at different depth levels, and ascent Cerro Tuzgle id fed by mantel melts which are imaged as a plume of low Qp material that reaches to the strong earthquake cluster at 200 km depth.
