Communication, Education and Outreach (CEO)
	LANL/SCEC Earthquakes and Urban Infrastructure Project

Earthquakes and Urban Infrastructure: Excerpt from the Workshop Proceedings, April 1998

The purpose of our workshop, "Earthquakes and Urban Infrastructure," was to engage knowledgeable representatives of infrastructure organizations in a small workshop setting that encouraged information exchange among scientists, practicing professionals, and government officials. We hoped participants would supply us with input about their needs at the beginning of this collaboration, which links modeling of regional ground motion with infrastructure damage, emergency response, and recovery, with the goal of using the models for urban infrastructure planning.

During the first day, we covered a lot of ground: what is known about the seismic hazard in the Los Angeles region, what scientists and engineers have accomplished in terms of modeling that hazard, and how that information can be fed into more realistic risk analyses.

On the second day, we solicited feedback from all participants. This was done through a structured interchange designed to enable each participant to provide specific suggestions on how they might use the models discussed. We used the Nominal Group Technique during our breakout sessions to produce consensus responses.

For the breakout sessions. all Workshop participants and presenters were assigned to one of four groups, which convened in separate rooms. Each group was led by an individual who presented several topics and questions related to the previous day's presentations and discussions, and then systematically collected suggestions and feedback to be used in this summary document.

Background

The vitality of our national infrastructure is critical to our national security. We contend that our nation is most vulnerable where the infrastructure elements converge in cities. Earthquakes severely stress the urban infrastructure system and can be a major test of our understanding of how infrastructure elements are linked. Such stresses have been clearly demonstrated at Northridge (California, 1994), Kobe (Japan, 1995), and Mexico City (1985). A primary cause of the damage in these events is attributed to complex geologic structures such as sedimentary basins, which amplify and prolong ground motion.

The Southern California Earthquake Center (SCEC) is focused on the earthquake hazard in the greater Los Angeles region. SCEC is simulating ground motions from a variety of sources in southern California, including earthquakes on the San Andreas fault and major faults in the Los Angeles basin. These simulations can be used to forecast probable ground motions throughout the southern California urban environment, such as the Downtown/Wilshire corridor and the ports of Los Angeles and Long Beach. In addition, the Northridge earthquake provides a database of measured ground motions, coupled with damage to the urban infrastructure. Thus, the Northridge earthquake can provide a test for the developing model. Given the density and variability of infrastructure in the downtown and port areas, simulations of earthquakes on the Elysian Park and Palos Verdes faults are particularly appropriate for testing the Los Alamos damage modules for predicting damage to urban subsystems.

In parallel with adaptation of the earthquake simulation codes, damage modules will be developed so that the modeled pattern of ground motions can be projected into specific predictions of damage to urban subsystems and to critical parts of the infrastructure. For example, downed communi-cations will adversely affect the electrical power system, transportation, and food and goods distribution, and these feed back into effects on general recovery efforts. Infrastructure systems analysis capabilities will then be applied to emergency response and sustainable development planning, infrastructure vulnerability assessment, and a range of natural disaster scenarios beyond earth-quakes.

The high-performance computing platform being implemented in the Los Alamos National Laboratory Urban Security Initiative program, for example, is an excellent platform on which to perform simulations of the necessary size and resolution (order 107-108 finite difference cells) to accurately predict ground motion patterns. SCEC and Los Alamos propose working on development of nonlinear modules that will enable existing elastic codes to better predict ground motion in areas of high vulnerability. The combination of unprecedented problem size, resolution, and nonlinear wave propagation will be used for seismic risk modeling. High-performance computing benefits infrastructure systems analyses as well, particularly for large regions and networks, large populations, many different scenarios, and sensitivity studies.

The Los Angeles Basin and Kobe, Japan, provide validation for earthquake simulation codes, because of their well-characterized geology, excellent geophysical monitoring, and infrastructure data. Validation of the developing urban system framework and high-level decision tools will play a major role in distinguishing Los Alamos' Urban Security Competency.

Download the Workshop Proceedings (Adobe PDF file- 333K).

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