Generating Random Earthquake Events for Probabilistic Tsunami Hazard Assessment

LeVeque, Randall J.
Waagan, Knut
González, Frank I.
Rim, Donsub
Lin, Guang
Date Issued
LeVeque, Randall J.; Waagan, Knut; González, Frank I.; Rim, Donsub; Lin, Guang. Generating Random Earthquake Events for Probabilistic Tsunami Hazard Assessment. Pure and Applied Geophysics 2016 ;Volum 173.(12) s. 3671-3692
Size: 3M
To perform probabilistic tsunami hazard assessment for subduction zone earthquakes, it is necessary to start with a catalog of possible future events along with the annual probability of occurrence, or a probability distribution of such events that can be easily sampled. For near-field events, the distribution of slip on the fault can have a significant effect on the resulting tsunami. We present an approach to defining a probability distribution based on subdividing the fault geometry into many subfaults and prescribing a desired covariance matrix relating slip on one subfault to slip on any other subfault. The eigenvalues and eigenvectors of this matrix are then used to define a Karhunen-Loève expansion for random slip patterns. This is similar to a spectral representation of random slip based on Fourier series but conforms to a general fault geometry. We show that only a few terms in this series are needed to represent the features of the slip distribution that are most important in tsunami generation, first with a simple one-dimensional example where slip varies only in the down-dip direction and then on a portion of the Cascadia Subduction Zone.
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