USGS National Seismic Hazard Mapping Project

USGS National Seismic Hazard Mapping Project
Name	USGS National Seismic Hazard Mapping Project
Formed	1996
Parent	United States Geological Survey
Jurisdiction	United States

USGS National Seismic Hazard Mapping Project

The National Seismic Hazard Mapping Project produces probabilistic seismic hazard maps and related products for the United States and territories, informing building codes, risk assessments, and disaster planning for agencies such as the Federal Emergency Management Agency, National Institute of Standards and Technology, and state seismic commissions. Its outputs integrate paleoseismology, geodesy, and seismicity datasets from institutions including the United States Geological Survey, California Geological Survey, University of California, Berkeley, Southern California Seismic Network, and international partners like the United States Geological Survey (external)—serving stakeholders such as the American Society of Civil Engineers, National Research Council (United States), and insurance regulators.

Overview

The Project generates probabilistic seismic hazard assessments that combine earthquake catalogs, fault models, and ground motion prediction equations produced by teams at the United States Geological Survey, California Institute of Technology, Massachusetts Institute of Technology, Stanford University, and the Nevada Seismological Laboratory. Outputs include seismic hazard maps, uniform hazard spectra used by the International Building Code, and hazard curves employed by the Federal Emergency Management Agency, Department of Homeland Security, National Oceanic and Atmospheric Administration, and state emergency management agencies. Collaborative efforts involve the Southern California Earthquake Center, Pacific Northwest Seismic Network, Alaska Division of Geological & Geophysical Surveys, and private sector partners in engineering and insurance.

History and Development

Launched in 1996 under direction from Congress and influenced by events like the 1994 Northridge earthquake, the Project built on earlier seismic research at the United States Geological Survey and academic programs at institutions such as University of California, Los Angeles, University of Washington, Oregon State University, and Brown University. Key milestones include the 1996 national map release, updates following the 1995 Kobe earthquake and 2001 Nisqually earthquake, integration of global positioning system data from the International GNSS Service, and multi-institutional hazard model collaborations with the Southern California Earthquake Center and the National Earthquake Hazards Reduction Program.

Methodology and Models

The Project employs probabilistic seismic hazard analysis (PSHA) frameworks developed by researchers at the Seismological Society of America, American Geophysical Union, Earthquake Engineering Research Institute, and academic centers like Columbia University and Cornell University. Inputs include earthquake catalogs from the Centennial Earthquake Catalog and regional networks such as the Alaska Volcano Observatory, fault databases maintained by the California Geological Survey and Arizona Geological Survey, and deformation rates from NASA and the Jet Propulsion Laboratory. Ground motion models incorporate empirical relationships from teams at California Institute of Technology, University of California, Santa Barbara, University of California, Los Angeles, and international collaborators at Imperial College London and ETH Zurich.

Hazard Maps and Products

Published products include national seismic hazard maps, state supplements for jurisdictions such as California, Alaska, Hawaii, and Puerto Rico, and design spectra used by the International Building Code and American Society of Civil Engineers standards. Specialized products target lifelines and critical infrastructure overseen by the Department of Transportation, Federal Aviation Administration, United States Army Corps of Engineers, and utilities regulated by state public utility commissions. The Project also produces scenario maps for notable faults like the San Andreas Fault, Cascadia subduction zone, New Madrid Seismic Zone, and the Wasatch Fault.

Applications and Impact

Outputs inform seismic provisions in building codes adopted by municipalities including Los Angeles, San Francisco, Seattle, and Anchorage, and influence retrofit programs overseen by agencies such as the Federal Emergency Management Agency and the National Institute of Standards and Technology. Insurers and reinsurers, including firms in New York City and global markets, use hazard curves for exposure modeling; infrastructure owners such as the Port of Long Beach, Los Angeles Department of Water and Power, and federal asset managers rely on hazard assessments for resilience planning. Academic research at institutions like University of California, Berkeley, Princeton University, and University of Texas at Austin uses Project datasets for seismic risk and urban resilience studies.

Criticism and Limitations

Critiques from scholars at Harvard University, Columbia University, and independent consultants note uncertainties in seismicity rates, fault slip rates, and ground motion prediction equations—particularly for complex sources like the Cascadia subduction zone and intraplate regions such as the New Madrid Seismic Zone. Limitations include sparse paleoseismic data in some regions, model epistemic uncertainty highlighted by the National Research Council (United States), and challenges integrating induced seismicity associated with energy activities regulated by state oil and gas commissions and scrutinized by research at Stanford University and Texas A&M University.

Future Directions and Updates

Planned advances incorporate dense geodetic observations from networks like the Plate Boundary Observatory, improved paleoseismology from teams at University of Nevada, Reno and Utah Geological Survey, and enhanced ground motion models using physics-based simulations from groups at Lawrence Livermore National Laboratory, Sandia National Laboratories, and the Pacific Northwest National Laboratory. Ongoing collaborations with the National Science Foundation, National Aeronautics and Space Administration, and international partners aim to refine hazard maps for climate resilience, critical infrastructure managed by the United States Department of Energy, and urban planning in metropolitan areas such as New York City, Chicago, and Miami.

Category:Seismology