[Depfis] prediccion notable

Mie Mar 3 13:35:12 ART 2010

Hola,

Un colega me hizo llegar una copia de un trabajo publicado en 2009  
cuyos autores son geofisicos franceses, chilenos y bulgaros. El  
trabajo, publicado en la revista "Physics of the earth and planetary  
interiors", termina con la siguiente conclusion: "It is possible that  
the northern part of the plate interface between Constitución and  
Concepción was affected by the earthquakes of 1851, 1928 and 1939, but  
it is unlikely that this was the case near the city of Concepción. We  
would then conclude that the southern part of the  
Concepción-Constitución gap has accumulated a slip deficit that is  
large enough to produce a very large earthquake of about Mw= 8.0-8.5."  
Bastante impresionante como prediccion. Abajo copio el abstract. El  
pdf puede obtenerse electronicamente. Saludos,

Juan Pablo

--------------------------------------------------------------------------------
J.C. Ruegg, A. Rudloff, C. Vigny, R. Madariaga, J.B. de Chabalier, J.  
Campos, E. Kausel, S. Barrientos, D. Dimitrov (2009) Interseismic  
strain accumulation measured by GPS in the seismic gap between  
Constitución and Concepción in Chile. Physics of the Earth and  
Planetary Interiors 175:78-85

Abstract
The Concepción-Constitución area [35-37°S] in South Central Chile is  
very likely a mature seismic gap, since no large subduction earthquake  
has occurred there since 1835. Three campaigns of global positioning  
system (GPS) measurements were carried out in this area in 1996, 1999  
and 2002. We observed a network of about 40 sites, including two  
east-west transects ranging from the coastal area to the Argentina  
border and one north-south profile along the coast. Our measurements  
are consistent with the Nazca/South America relative angular velocity  
(55.9°N, 95.2°W, 0.610°/Ma) discussed by Vigny et al. (2008, this  
issue) which predicts a convergence of 68mm/year oriented 79°N at the  
Chilean trench near 36°S. With respect to stable South America,  
horizontal velocities decrease from 45mm/year on the coast to  
10mm/year in the Cordillera. Vertical velocities exhibit a coherent  
pattern with negative values of about 10mm/year on the coast and  
slightly positive or near zero in the Central Valley or the  
Cordillera. Horizontal velocities have formal uncertainties in the  
range of 1-3mm/year and vertical velocities around 3-6mm/year. Surface  
deformation in this area of South Central Chile is consistent with a  
fully coupled elastic loading on the subduction interface at depth.  
The best fit to our data is obtained with a dip of 16±3°, a locking  
depth of 55±5 km and a dislocation corresponding to 67mm/year oriented  
78°N. However in the northern area of our network the fit is improved  
locally by using a lower dip around 13°. Finally a convergence motion  
of about 68mm/year represents more than 10m of displacement  
accumulated since the last big interplate subduction event in this  
area over 170 years ago (1835 earthquake described by Darwin).  
Therefore, in a worst case scenario, the area already has a potential  
for an earthquake of magnitude as large as 8-8.5, should it happen in  
the near future.

Dr Juan Pablo Paz
Profesor Titular UBA, Investigador Principal CONICET
Departamento de Fisica & Instituto de Fisica de Buenos Aires
FCEyN UBA, Pabellon 1, Ciudad Universitaria
1428 Buenos Aires, Argentina
Email: paz en df.uba.ar
Phone: +54-11-45763353
  http://www.df.uba.ar/users/paz[1]
  http://www.qufiba.df.uba.ar[2]

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[1] http://www.df.uba.ar/users/paz
[2] http://www.qufiba.df.uba.ar
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