Precursory transient slip during the 2001 Mw = 8.4 Peru earthquake sequence from continuous GPS

[1] Two-hour position estimates from a continuous GPS station located at Arequipa, Peru, document precursory deformation beginning 18 hours prior to an Mw = 7.6 aftershock of the June 23rd 2001 Mw = 8.4 earthquake. This preseismic signal appears on the north and east components as a slow displacement with an amplitude twice that of the subsequent coseismic. Analysis of three years of 18-hour rate measurement shows this signal to be unprecedented and beyond four standard deviations from the mean rate. The best fitting centroid is directionally consistent with slow slip along the plate interface and suggests the preseismic deformation arises from creep near the aftershock rupture. This implies the Nazca-South American plate interface slipped slowly prior to seismogenic faulting. These observations indicate the Mw = 7.6 earthquake grew out of slow slip along the plate interface and clearly demonstrate the breadth of slip rates accommodated by subduction zone plate interfaces.

[1]  K. Larson,et al.  Transient fault slip in Guerrero, southern Mexico , 2001 .

[2]  Timothy Ian Melbourne,et al.  Rapid postseismic transients in subduction zones from continuous GPS , 2002 .

[3]  James L. Davis,et al.  GPS APPLICATIONS FOR GEODYNAMICS AND EARTHQUAKE STUDIES , 1997 .

[4]  V. E. Levin,et al.  Rapid aseismic moment release following the 5 December, 1997 Kronotsky, Kamchatka, Earthquake , 2001 .

[5]  H. Scherneck.  A parametrized solid earth tide model and ocean tide loading effects for global geodetic baseline measurements , 1991 .

[6]  Paul Segall,et al.  Volcano monitoring using the Global Positioning System: Filtering strategies , 2001 .

[7]  J. Zumberge,et al.  Precise point positioning for the efficient and robust analysis of GPS data from large networks , 1997 .

[8]  T. Sagiya,et al.  The 1992 Sanriku-Oki, Japan, Ultra-Slow Earthquake , 1995 .

[9]  Kelin Wang,et al.  A Silent Slip Event on the Deeper Cascadia Subduction Interface , 2001, Science.

[10]  S. Miyazaki,et al.  A slow thrust slip event following the two 1996 Hyuganada Earthquakes beneath the Bungo Channel, southwest Japan , 1999 .

[11]  J. Ruegg,et al.  Co-, Post- and Pre(?)-seismic Displacements Associated with the Mw 8.4 Southern Peru Earthquake of 23 June 2001 from Continuous GPS Measurements , 2001 .

[12]  Chris Marone,et al.  The depth of seismic faulting and the upper transition from stable to unstable slip regimes , 1988 .

[13]  L. Ruff,et al.  Analysis of the 23 June 2001 Mw = 8.4 Peru underthrusting earthquake and its aftershocks , 2002 .

[14]  J. Dieterich.  Earthquake nucleation on faults with rate-and state-dependent strength , 1992 .