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Volcanic uplift, caused by the accumulation of magma in subsurface reservoirs, is a common precursor to eruptions. But, for some volcanoes, uplift of metres or more has not yet led to an eruption. Here we present displacement maps of volcanoes in the Galápagos Islands, constructed using satellite radar interferometry, that might help explain this dichotomy.(More)
Remeasurement of a triangulation network in the southern part of the New Madrid seismic zone with the Global Positioning System has revealed rapid crustal strain accumulation since the 1950s. This area experienced three large (moment magnitudes >8) earthquakes in 1811 to 1812. The orientation and sense of shear is consistent with right-lateral strike slip(More)
Probabilistic estimates of earthquake hazard use various models for the temporal distribution of earthquakes, including the 'time-predictable' recurrence model formulated by Shimazaki and Nakata (which incorporates the concept of elastic rebound described as early as 1910 by H. F. Reid). This model states that an earthquake occurs when the fault recovers(More)
[1] Postseismic displacements of as much as 14 cm were recorded by GPS measurements in the 3 months following the M W 7.6 1999 Chi-Chi, Taiwan earthquake. Data from 35 continuous and 90 campaign-surveyed stations, which show continued east over west thrusting, are analyzed to estimate the postseismic slip distribution and fault geometry. Assuming the(More)
Mauna Loa volcano, Hawaii, deforms by a combination of shallow dike intrusions in the rift zones and earthquakes along the base of the volcano, but it is not known how the spreading is accommodated in the lower part of the volcanic edifice. We present evidence from interferometric synthetic aperture radar data for secular inflation of a dike-like magma body(More)
Satellite radar interferometry data reveal strong localized uplift in a semi-circular pattern on the southwest flank of Fernandina volcano, Galápagos, where an eruption took place in January to April, 1995. The observations show a maximum decrease in radar range of 0.75 m, and they are consistent with a model of a shallow-dipping dike intrusion feeding this(More)
[1] Earthquake nucleation requires reduction of frictional strength = (À p) with slip or slip rate, where , n , and p are the friction coefficient, normal stress, and fluid pressure, respectively. For rate state at fixed (À p), instabilities can occur when d ss /dv < 0, where ss is the steady state friction and v is slip rate. Shear heating increases p and,(More)
We use GPS displacements collected in the 15 months after the 1999 Chi-Chi, Taiwan earthquake (M w 7.6) to evaluate whether post-seismic deformation is better explained by afterslip or viscoelastic relaxation of the lower crust and upper mantle. We find that all viscoelas-tic models tested fail to fit the general features in the post-seismic GPS(More)
The horizontal displacements accompanying the 1906 San Francisco earthquake and the 1989 Loma Prieta earthquake are computed from geodetic survey measurements. The 1906 earthquake displacement field is entirely consistent with right-lateral strike slip on the San Andreas fault. In contrast, the 1989 Loma Prieta earthquake exhibited subequal components of(More)