Aftershock forecasting in Hawai`i: accounting for a complex mix of tectonic and magmatic processes.

Olana R. Costa, & Andrew J. Michael

Submitted September 10, 2023, SCEC Contribution #12827, 2023 SCEC Annual Meeting Poster #159

Earthquake aftershock forecasts serve to relay situational awareness of the probability of experiencing aftershocks to the public, emergency managers, and other people who make decisions about response and recovery activities. Currently, the U.S. Geological Survey (USGS) generates forecasts automatically for earthquakes of magnitude 5 and greater in the United States and U.S. territories using the statistical model of aftershock rate developed by Reasenberg and Jones (Science, 1989). However, forecasts are not generated automatically for earthquakes that occur in Hawai`i due to the influence that the state’s magmatism has on its aftershock sequences. Generating an aftershock forecast requires the determination of regional model parameters that best suit earthquake clustering for the area of focus. These parameters vary greatly in Hawai`i depending on the mainshock’s proximity to active magmatism as well as its association with flexural stress on the underlying Pacific plate and the evolution of Kīlauea’s south flank. The USGS is actively updating its aftershock forecasting model from the current Reasenberg and Jones (1989) method to the Epidemic-Type Aftershock Sequence (ETAS) model from Ogata (J. Am. Stat. Assoc., 1988), in which aftershocks creating their own aftershock sequences is taken into consideration. The ETAS model can also allow for a time-varying rate of independent earthquakes that may be useful for modeling sequences that are partially caused by magmatism. Using seismicity recorded by the USGS Hawaiian Volcano Observatory since 1960, we present a suite of ETAS model parameters estimated for regions in Hawai`i that vary by their relation to Hawai`i’s different magmatic and tectonic processes.

Key Words
Aftershocks, Hawaii, Volcano, ETAS

Citation
Costa, O. R., & Michael, A. J. (2023, 09). Aftershock forecasting in Hawai`i: accounting for a complex mix of tectonic and magmatic processes.. Poster Presentation at 2023 SCEC Annual Meeting.

Related Projects & Working Groups
Earthquake Forecasting and Predictability (EFP)