Upper plate deformation measured by GPS in the Coquimbo Gap, Chile

摘要: Abstract Since the Mw = 7.3 Punitaqui earthquake in 1997, area between 30°S and 32°S (Coquimbo-Illapel section) of Chilean subduction has been locus a decennial seismic swarm. A dense network 30+ benchmarks have installed this surveyed six times with high precision GPS over last 3 years. Surface deformation here is compatible elastic loading due to partial locking on interface at depth. Here we show that area, only 40–45% total convergence rate Nazca South America plates gives way accumulation upper plate, remaining 60–55% being dissipated by free or aseismic slip, cumulative slip swarm explaining no more than 1/3rd 1/4th it. We also find decreases northward, reach almost zero around (La Serena – Tongoy). Whether steady state transient pattern (a decrease coupling) not clear since our measurements span years early 10 ago were sparse differ marginally from ours.