HR: 16:00h
AN: G24A-01 INVITED    [Abstracts]
TI: Towards Real-time Recognition of Near-Field Tsunamigenic Earthquakes
AU: * Dragert, H
EM: hdragert@nrcan.gc.ca
AF: Geological Survey of Canada, Pacific Geoscience Centre, 9860 West Saanich Road, Sidney, BC V8L 4B2, Canada
AU: Schmidt, M
EM: mschmidt@nrcan.gc.ca
AF: Geological Survey of Canada, Pacific Geoscience Centre, 9860 West Saanich Road, Sidney, BC V8L 4B2, Canada
AU: Lu, Y
EM: ylu@nrcan.gc.ca
AF: Geological Survey of Canada, Pacific Geoscience Centre, 9860 West Saanich Road, Sidney, BC V8L 4B2, Canada
AU: Rogers, G
EM: grogers@nrcan.gc.ca
AF: Geological Survey of Canada, Pacific Geoscience Centre, 9860 West Saanich Road, Sidney, BC V8L 4B2, Canada
AU: Rosenberger, A
AF: Geological Survey of Canada, Pacific Geoscience Centre, 9860 West Saanich Road, Sidney, BC V8L 4B2, Canada
AB: Whether a tsunami has been generated from a large earthquake immediately offshore cannot be determined within a crucial time window from traditional seismic or tide gauge data alone. Geodetic data show that coseismic motions of the Earth's surface, even hundreds of kilometres from the earthquake, can be used to determine the nature of the rupture and whether the earthquake is likely tsunamigenic. High-rate data (1 Hz or greater) from continuous GPS stations located along the coastal margin can provide on-line streamed data that can be analyzed in real time to provide relative positions to an accuracy of 1-2 cm horizontally and 3-5 cm vertically with a latency of a few seconds. Regional ground displacements at the time of a major offshore earthquake could therefore point to the certainty of a tsunami within several minutes. Likewise, a coastal network of strong- motion instruments transmitting data in real-time can provide an immediate estimate of rupture propagation and rupture length and thereby possesses the same rapid tsunami discrimination potential. The Geological Survey of Canada, in cooperation with the Canadian Hydrographic Service has set up a small network of geodetic quality GPS installations with continuous on-line IP communications. This facilitates real-time positioning along the coast of the Canadian segment of the Cascadia subduction zone. The aim is to evaluate the realizability and effectiveness of automatically determining major vertical and horizontal motion at coastal versus inland GPS stations that would unambiguously and rapidly indicate tsunami generation. In addition, a prototype network of smart strong-motion seismographs is being deployed in the coastal region. Determining the length and character earthquake of rupture in the immediate offshore region using on-scale seismic data should also provide real-time tsunami discrimination. It is hoped that these relatively low cost techniques can become mainstream tools of tsunami warning systems worldwide.
DE: 1242 Seismic cycle related deformations (6924, 7209, 7223, 7230)
DE: 4564 Tsunamis and storm surges
DE: 7215 Earthquake source observations (1240)
DE: 7240 Subduction zones (1207, 1219, 1240)
SC: Geodesy [G]
MN: 2007 Fall Meeting