Export 2 results:
Sort by: [ Author  (Asc)] Title Type Year
A B C D E F G H I J K L M N O P Q [R] S T U V W X Y Z   [Show ALL]
Rasmussen, L, Bromirski PD, Miller AJ, Arcas D, Flick RE, Hendershott MC.  2015.  Source location impact on relative tsunami strength along the US West Coast. Journal of Geophysical Research-Oceans. 120:4945-4961.   10.1002/2015jc010718   AbstractWebsite

Tsunami propagation simulations are used to identify which tsunami source locations would produce the highest amplitude waves on approach to key population centers along the U.S. West Coast. The reasons for preferential influence of certain remote excitation sites are explored by examining model time sequences of tsunami wave patterns emanating from the source. Distant bathymetric features in the West and Central Pacific can redirect tsunami energy into narrow paths with anomalously large wave height that have disproportionate impact on small areas of coastline. The source region generating the waves can be as little as 100 km along a subduction zone, resulting in distinct source-target pairs with sharply amplified wave energy at the target. Tsunami spectral ratios examined for transects near the source, after crossing the West Pacific, and on approach to the coast illustrate how prominent bathymetric features alter wave spectral distributions, and relate to both the timing and magnitude of waves approaching shore. To contextualize the potential impact of tsunamis from high-amplitude source-target pairs, the source characteristics of major historical earthquakes and tsunamis in 1960, 1964, and 2011 are used to generate comparable events originating at the highest-amplitude source locations for each coastal target. This creates a type of ``worst-case scenario,'' a replicate of each region's historically largest earthquake positioned at the fault segment that would produce the most incoming tsunami energy at each target port. An amplification factor provides a measure of how the incoming wave height from the worst-case source compares to the historical event.

Rudman, AJ, Mallick S, Frazer LN, Bromirski P.  1993.  Workstation computation of synthetic seismograms for vertical and horizontal profiles: A full wavefield response for a two-dimensional layered half-space. Computers & Geosciences. 19:447-474.   10.1016/0098-3004(93)90095-m   AbstractWebsite

FORTRAN code for generation of full wavefield synthetic seismograms is presented for two-dimensional horizontally layered models bounded by a free surface and a half space. Model layers are user defined by compressional and shear velocities, Q factors, densities and thicknesses. The algorithm is based on the reflectivity method and uses the propagator matrix approach. Explosion (point) and double couple (fault) sources are generated with a moment tensor representation. As evaluation of the slowness integrals involves time consuming numerical Hankel transforms, these computations are made with a generalized Filon method that saves computational time. The architecture of the program is unusual because the outermost loop is over temporal frequency and the innermost loop is over slowness. This permits the use of frequency-dependent seismic velocities, necessary for causality, while giving a factor of seven speed-up from vectorization. The codes are applicable for both vector computers and workstations. Two test cases demonstrate successful applications of the codes for both horizontal seismic profiles (receivers at one depth at successively larger offsets) and for vertical seismic profiles (receivers arranged in a vertical array at any offset). Receivers and source may be positioned within any layer. The seismograms display direct, refracted, reflected, and head-wave arrivals and their multiples. Mode converted events of compressional and shear propagation are generated and identified. The code generates seismograms for pressure, vertical and horizontal displacement sensors and for models combining acoustic and elastic layers.