Probabilistic prediction

Probabilistic Prediction of Rupture and Slip

 

Earthquake Early Warning (EEW) predicts future ground shaking based on presently available data. Long ruptures present the best opportunities for EEW since many heavily shaken areas are distant from the earthquake epicenter and may receive long warning times. Predicting the shaking from large earthquakes, however, requires some estimate of the likelihood of the future evolution of an ongoing rupture. An EEW system that anticipates future rupture using the present magnitude (or rupture length) together with the Gutenberg-Richter frequency-size statistics will likely never predict a large earthquake, because of the rare occurrence of extreme events. However, it seems reasonable to assume that large slip amplitudes increase the probability for evolving into a large earthquake. In order to investigate the relationship between the slip and the eventual size of an ongoing rupture, we simulate suites of 1-D rupture series from stochastic models of spatially heterogeneous slip. We find that while large slip amplitudes increase the probability for the continuation of a rupture and the possible evolution into a Big One, the recognition that rupture is occurring on a spatially smooth fault has an even stronger effect. We conclude that an EEW system for large earthquakes needs some mechanism for the rapid recognition of the causative fault (e.g., from real-time GPS measurements) and consideration of its smoothness. An EEW system for large earthquakes on smooth faults, such as the San Andreas Fault, could be implemented in two ways: the system could issue a warning, whenever slip on the fault exceeds a few meters, because the probability for a large earthquake is high and strong shaking is expected to occur in large areas around the fault. A more sophisticated EEW system could use the present slip on the fault to estimate the final rupture dimensions and future slip evolution, and (using this information) could provide probabilistic predictions of seismic ground motions along the evolving rupture. The decision on whether an EEW system should be realized in the first or in the second way (or in a combination of both) is user-specific.

 

 

References:

Bӧse, M. and T.H. Heaton, 2010: Probabilistic Prediction of Rupture Length, Slip and Seismic Ground Motions for an Ongoing Rupture - Implications for Early Warning for Large Earthquakes, Geophys. J. Int., 183(2), pp. 1014-1030, doi: 10.1111/j.1365-246X.2010.04774.x link

 

 

Last up-date:

12/13/2012

Maren Bӧse, Phd

Senior ReseaRch Fellow