Possible reduction of earthquake hazard on the Wellington Fault, New Zealand, after the nearby 1855, M 8.2 Wairarapa earthquake and implication for interpreting paleoearthquake intervals

Abstract

Based on the indicative modelling, the changes in Coulomb failure function (ΔCFS) suggest that the W-HV segment and the T-P segment could be stable in at least the future 300 years and 190 years respectively, for these periods should be needed to accumulate the stress released by the M 8.2 Wairarapa earthquake, assuming that there is no influence from the sources, the earthquake did not alter the failure threshold, and that failure is a fairly deterministic process. The results also show that the influence on the W-HV segment and T-P segment of the Wellington Fault caused by the 1855, M 8.2 Wairarapa earthquake is significant considering that the average fault rupture recurrence interval on the Wellington Fault is about 500-770 years. With our present understanding of the Wellington and Wairarapa faults, it can be concluded that the 1855 Wairarapa earthquake retarded earthquake occurrence on the W-HV segment and the T-P segment of the Wellington Fault. Thus the seismic hazard in the Wellington region may be over-estimated.