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Interseismic strain accumulation in south central Chile from GPS measurements, 1996–1999
Author(s) -
Ruegg J. C.,
Campos J.,
Madariaga R.,
Kausel E.,
de Chabalier J. B.,
Armijo R.,
Dimitrov D.,
Georgiev I.,
Barrientos S.
Publication year - 2002
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2001gl013438
Subject(s) - subduction , geology , global positioning system , seismology , range (aeronautics) , tectonics , telecommunications , materials science , computer science , composite material
Two campaigns of Global Positioning System (GPS) measurements were carried out in the Concepción‐Constitución area of Chile in 1996 and 1999. It is very likely that this area is a mature seismic gap, since no subduction earthquake has occurred there since 1835. In 1996, 32 sites were occupied in the range 35°S–37°S, between the Pacific coast of Chile and the Andes near the Chile‐Argentina border. In 1999, the network was extended by the installation of 9 new points in the Arauco region whereas 13 points among the 1996 stations were reoccupied. The analysis of this campaign data set, together with the data recorded at eight continuous GPS sites (mostly IGS stations) in South America and surrounding regions, indicates a velocity of about 40 ± 10 mm/yr in the direction N80–90°S for the coastal sites with respect to stable cratonic South America. This velocity decreases to about 20–25 mm/yr towards the Andes. We interpret this result as reflecting interseismic strain accumulation above the Nazca‐South America subduction zone, due to a locked thrust zone extending down to about 60 km depth.