HR: 1340h
AN: S13A-1029    [Abstracts]
TI: Dynamic Seismic Hazard Model for New Zealand
AU: * Tormann, T
EM: t.tormann@web.de
AF: Victoria University of Wellington, Kelburn Parade PO Box 600, Wellington, 6001 New Zealand
AU: Savage, M K
EM: martha.savage@vuw.ac.nz
AF: Victoria University of Wellington, Kelburn Parade PO Box 600, Wellington, 6001 New Zealand
AU: Stirling, M
EM: m.stirling@gns.cri.nz
AF: Institute of Geological and Nuclear Sciences LTD, 69 Gracefield Rd PO Box 30-368, Lower Hutt, 6009 New Zealand
AB: We are creating a new dynamic seismic hazard model for New Zealand to add the effects of short-term hazard fluctuations due to earthquake triggering to the current Poissoninan probability from the national probabilistic seismic hazard model. Prospective foreshock probability decay is modeled as a function of origin time and epicentral distance from the potential foreshock, and the magnitude difference between foreshock-mainshock pairs. Preliminary results show that some parameters are different for the Taupo Volcanic Zone (TVZ) compared to the rest of New Zealand. In both regions, the magnitude probability distribution follows the Gutenberg-Richter relationship with a b-value of 1.3. In the TVZ, the foreshock probability decreases with approximately $1/t^{2.4 \pm 0.5}$ and $1/r^{3.62 \pm 0.03}$. Elsewhere, the decay with time and distance is smaller, at $1/t^{1.6 \pm 0.2}$ and $1/r^{2.7 \pm 0.2}$. Combining this information with a generic aftershock model, we calculate fluctuating daily hazard maps for New Zealand, showing the regional probability distribution for peak ground accelerations of 0.05g or more being observed. We are developing a methodology to test these ground motion forecasts against 40 years of strong motion observations in New Zealand.
DE: 7223 Seismic hazard assessment and prediction
DE: 7230 Seismicity and seismotectonics
SC: Seismology [S]
MN: 2004 AGU Fall Meeting