Uncertainty in Earthquake Source Inversions

I am interested in the resolving power of seismic data. Kinematic inversions are routinely used to image the rupture process at depth, but differences between various slip inversions make it clear that the uncertainties in these inversions can be quite large. Data fit is not necessarily a good measure of the error in the final slip model. It seems that many features we would like to extract (for example, rupture area, maximum slip, the size and location of asperities) are not robust features of earthquake source models. A better understanding of which features in inversions are robust will allow this research to be applied in ways that are suitable given the information that they provide.

Page, Morgan T., Susana Custódio, Ralph J. Archuleta, and J. M. Carlson, Constraining Earthquake Source Inversions with GPS Data 1: Resolution Based Removal of Artifacts, JGR - Solid Earth, in press.

Seismic Hazard Analysis

Rigorous methodology in Probabilistic Seismic Hazard Analysis (PSHA) requires fully accounting for model uncertainty. PSHA is characterized by deep uncertainty, for not only is there parameter uncertainty regarding the values of various parameters needed to estimate hazard, there is also model uncertainty stemming from uncertainty regarding the mechanism generating risk. The ability of logic trees, as currently implemented in PSHA, to correctly capture model uncertainty is limited. Logic trees are most easily implemented when a) the branches at each level of the logic tree are mutually exclusive, and b) the uncertainties sampled at each level of the logic tree are uncorrelated.

Page, M. T. and J. M. Carlson (2006),Methodologies for Earthquake Hazard Assessment: Model Uncertainty and the WGCEP-2002 Forecast, Bull. Seism. Soc. Am. 96, 5, doi: 10.1785/0120050195

Dynamic Rupture Modeling

Earthquake ground motions are the result of a complex and heterogeneous faulting process. Dynamic forward simulations, which include all of the physics of the earthquake problem, can include realistic friction mechanisms and simulate up to frequencies important for building response. While kinematic models provide a direct connection to data, dynamic models, being feasible physically, can help us better constrain the rupture processes that occur at the source.

Page, M. T., E. M. Dunham, and J. M. Carlson (2005), Distinguishing Barriers and Asperities in Near-Source Ground Motion, J. Geophys. Res. - Solid Earth. 110, B11302, doi:10.1029/2005JB003736.