IFIR   05409
INSTITUTO DE FISICA DE ROSARIO
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Cambios periódicos de gravedad vinculados con tectónica activa en la Precordillera Oriental, San Juan, Argentina.
Autor/es:
RUIZ, FRANCISCO; GIMENEZ, MARIO E; INTROCASO, A; MARTINEZ, M. PATRICIA; CORNAGLIA, LAURA LILIANA; LEIVA, LAURA; SISTERNA, JORGE
Lugar:
Salvador, Brasil 2009
Reunión:
Congreso; 11th International Congress of the Brazilian Geophysical Society,; 2009
Institución organizadora:
Sociedad brasilera de Geofísica
Resumen:
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Abstract
The
gravity signal contains information regarding changes in density at all depths
and can be used as a proxy for the strain accumulation in fault networks.
A
network of areal geodetic control (Red G1) was set up with the purpose of
establishing space-time relations in the evolution of the gravity field
produced by seismo-tectonic activity. The network is composite for 50 points
well materialized in the field, and extends over an about 2600 km2
area centered in the San Juan
city of Argentina.
These
bench marks were linked with precise gravity measurements carried out during
years 2000, 2004, 2007 and 2008. The gravity changes are evaluated taking as
fix the gravity value in the Instituto Geofísico Sismológico (UNSJ) station.
The relative gravity variation field shows a consistent relation with the
seismic activity with magnitudes higher than 3 in the area, which was frequent
during these years.
The
most outstanding results indicate that: A) An alignment of maxima with
variations up to +0.100 mGal occurs in the Southwest of the Pie de Palo range,
Barboza and Valdivia interior mountains. B) A generalized descent in gravity
changes to the east of Sierra Chica de Zonda range (topographic uplift). C) The
South of the Sierra Chica de Zonda range shows a marked quiescence in the bench
marks situated to the west and high changes (-0.090 mGal) to the East of the
range. D) A generalized gravity down (upward zone) in the stations situated
north of the San Juan River in the interval
2004-2000.
If
we assign the gravity variations as caused entirely by topographic changes, the
height variations would be in the neighborhood of 15 cm in the last 10 years.
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