Implications of the 26 December 2004 Sumatra–Andaman Earthquake on Tsunami Forecast and Assessment Models for Great Subduction-Zone Earthquakes
- 1 January 2007
- journal article
- Published by Seismological Society of America (SSA) in Bulletin of the Seismological Society of America
- Vol. 97 (1A), S249-S270
- https://doi.org/10.1785/0120050619
Abstract
Results from different tsunami forecasting and hazard assessment models are compared with observed tsunami wave heights from the 26 December 2004 Indian Ocean tsunami. Forecast models are based on initial earthquake information and are used to estimate tsunami wave heights during propagation. An empirical forecast relationship based only on seismic moment provides a close estimate to the observed mean regional and maximum local tsunami runup heights for the 2004 Indian Ocean tsunami but underestimates mean regional tsunami heights at azimuths in line with the tsunami beaming pattern (e.g., Sri Lanka, Thailand). Standard forecast models developed from subfault discretization of earthquake rupture, in which deep- ocean sea level observations are used to constrain slip, are also tested. Forecast models of this type use tsunami time-series measurements at points in the deep ocean. As a proxy for the 2004 Indian Ocean tsunami, a transect of deep-ocean tsunami amplitudes recorded by satellite altimetry is used to constrain slip along four subfaults of the M >9 Sumatra–Andaman earthquake. This proxy model performs well in comparison to observed tsunami wave heights, travel times, and inundation patterns at Banda Aceh. Hypothetical tsunami hazard assessments models based on end- member estimates for average slip and rupture length (Mw 9.0–9.3) are compared with tsunami observations. Using average slip (low end member) and rupture length (high end member) (Mw 9.14) consistent with many seismic, geodetic, and tsunami inversions adequately estimates tsunami runup in most regions, except the extreme runup in the western Aceh province. The high slip that occurred in the southern part of the rupture zone linked to runup in this location is a larger fluctuation than expected from standard stochastic slip models. In addition, excess moment release (∼9%) deduced from geodetic studies in comparison to seismic moment estimates may generate additional tsunami energy, if the exponential time constant of slip is less than approximately 1 hr. Overall, there is significant variation in assessed runup heights caused by quantifiable uncertainty in both first-order source parameters (e.g., rupture length, slip-length scaling) and spatiotemporal complexity of earthquake rupture.Keywords
This publication has 152 references indexed in Scilit:
- Slip correlations on a creeping faultGeophysical Research Letters, 2001
- Full interseismic locking of the Nankai and Japan‐west Kurile subduction zones: An analysis of uniform elastic strain accumulation in Japan constrained by permanent GPSJournal of Geophysical Research, 2000
- Observing plate motions in S.E. Asia: Geodetic results of the GEODYSSEA ProjectGeophysical Research Letters, 1999
- Seismicity and plate deformation below the Andaman arc, northeastern Indian OceanTectonophysics, 1993
- Seismic moment tensors and source depths determined by the simultaneous inversion of body and surface wavesPhysics of the Earth and Planetary Interiors, 1989
- Seismotectonics of subduction and back-arc rifting under the Andaman SeaTectonophysics, 1984
- On tsunami nucleation: II. An instantaneous modulated line sourcePhysics of the Earth and Planetary Interiors, 1982
- Physical size of tsunamigenic earthquakes of the northwestern PacificPhysics of the Earth and Planetary Interiors, 1981
- A note on tsunamis: their generation and propagation in an ocean of uniform depthJournal of Fluid Mechanics, 1973
- Mechanism of tsunami earthquakesPhysics of the Earth and Planetary Interiors, 1972