Finalizing the 2020 National Seismic Hazard Model for Hawaii

Session: Forthcoming Updates of the USGS NSHMs: Hawaii, Conterminous U.S. and Alaska
Type: Oral
Date: 4/28/2020
Time: 10:45 AM
Room: 230 + 235
Description: 

The USGS is updating the National Seismic Hazard Model for Hawaii which was last produced in 2001 and has been implemented in the U.S. building codes. The updated seismic source model now includes additional earthquakes since 1997, updated fault ruptures for flank decollement earthquakes and seismicity-based forecasts based on Gutenberg-Richter statistical projections. In addition, several large earthquakes, including the 2006 Mw 6.7 Kiholo Bay and the 2018 Mw 6.9 Leilani Estates earthquakes, provide abundant strong motion datasets that show good agreement with NGAWest2 and two local ground motion models. These ground motion models allow for more periods and site classes than ever before. Challenges in developing the model include assessing seismicity rates in a volcanic environment, delineating the locations and sizes of future flank events and evaluating earthquake rates and shaking intensities near Honolulu. The preliminary ground motions for 2% probability of exceedance in 50 years are high across the island of Hawaii and changes with respect to 2001 model are spatially complex, with models showing higher hazard on the southern coast of Hawaii. Results, once finalized, will be considered as input into future building codes and risk assessments. These draft hazard models were developed through an extensive deliberation process with scientists, engineers and other stakeholders.

Presenting Author: Mark D. Petersen

Authors