A critical requirement for accurately representing surface-atmosphere interactions within an atmospheric model is to realistically characterize the land surface. Data must be extracted from a geographical database and transformed so that it is consistent with the needs of the numerical model. In such a process, there are two major classes of error that must be understood and minimized whenever possible. The first class involves the accuracy, precision, and resolution of the geographical data itself. The second is error introduced by the transformations used to assimilate the data into the atmospheric model. Thus, this research has two coupled objectives: to understand the effects of errors within the geographical data base upon the accuracy of the atmospheric model simulation and to design optimal techniques for the transformation of the data.

Lawrence Livermore National Laboratory responded to the 17 January 1994, Northridge earthquake by sending an information gathering team to observe and study the collapse of the interchange between highways 14 and I-5 in the northern San Fernando Valley. This field team examined the structural failure at the interchange and the surface soil conditions, and they installed high-grain RefTek seismic recorders to record aftershocks. We recorded aftershocks for two weeks. Analyses of aftershock recordings in this report illustrate the degree of differential support motion for this site, and the higher than expected ground motion from an earthquake of this size and distance. We used the aftershock recordings of small earthquakes as empirical Green`s functions and synthesized strong ground motion at three sites in the interchange area. Results presented here are based on an assumption that the geology of the interchange area remained linear in its response to the main event.

This report identifies the colleges and universities attended by Senators elected to the 103rd Congress.