Project Summaries
Active Faults in the Puget Lowland
Mapping faults in the Puget Sound is a critical element in determining the present seismic hazard in the region. Using seismic reflection and surface mapping, geologists are attempting to determine the location, geometry, and slip rates of active faults in the Puget Lowland. Incorporating this information into the seismic hazard maps will greatly enhance their credibility and utility. Other links reporting on results of active faults investigations are SHIPS (Seismic Hazards in the Puget Sound) and Geologic Mapping and Urban Hazards.
Crustal and Benioff Zone Seismicity
This project provides support and new research in the area of cataloging Pacific Northwest seismicity. Direct support to the Pacific Northwest Seismic Network is provided directly through USGS internal funding and through topical support by the USGS external program. New research on crustal earthquake mechanisms and Benioff zone seismicity is carried out directly through this project. Models of Benioff seismicity are being developed that include petrologic phase changes as mechanisms and explain a lack of such seismicity beneath Oregon.
Earthquake Information
Contact: seis_info@geophys.washington.edu
Locations and discussions of the latest earthquake, notable earthquakes, earthquake catalogs, seismograms, reports, descriptions of current projects, and more are available at the Pacific Northwest Earthquake Information web site. The center is maintained by the University of Washington Geophysics Program, in cooperation with other northwest institutions and funding from the U.S. Geological Survey, the Department of Energy, and the University of Washington. Visit the web site for more information.
Instrumental Deformation Studies
GPS satellite data provides information on active deformation of the Pacific Northwest. This project supports the active acquisition of this type of data through the PANGA consortium, composed of several university groups, the USGS, and the Geological Survey of Canada. Two active, fixed GPS sites are maintained by this project. USGS external grants provide funding for maintenance of additional stations and research into processing and modeling of the GPS data.
Paleoseismology
Contact: Alan Nelson , 303-273-8592
Knowledge of when, where, how big, and how often large earthquakes occur is crucial for evaluating the seismic hazards of a region. Through field study of the geologic record of prehistoric earthquakes, geologists are developing a database of the chronology and magnitude of large prehistoric crustal earthquakes and their effects in Puget Sound and coastal Oregon.
Portland/Southwest Washington
Contact:Thomas Pratt, 206-543-7358
Investigating the regional seismic hazard includes study of regional fault zones in Portland using high-resolution seismic imaging (seismic reflection), imaging of the Columbia River- Snake River system using wide-angle seismic refraction, and testing of regional tectonic models in detailed studies of Mount Saint Helens and Mount Ranier seismic zones, and selected volcanic vent patterns. Results from the these studies are important for defining the seismic hazard regionally.
Real-time Strong Motion Instrumentation
The effects of earthquakes on local geology and coupling to buildings is studied through the use of special sesmometers that record large motions beyond the range of normal earthquake seismometers. These 'stong-motion' instruments are deployed in the Puget Sound region to analyze the effects of geology and building design on motions transmitted to buildings. This project supports and maintains two such strong motion instruments and cooperates in analyzing the data.
Seismic Hazard Maps
Contact: Mark Petersen 303-273-8456
All available information relevant to determining the rate of earthquake occurrence and activity of faults in the region is included in the seismic hazard maps. These maps are the most comprehensive product of the Earthquake Hazards Reduction Program and are updated every three years. For the most recent map of the Pacific Northwest, visit this site. For access to maps for the nation, visit National Seismic Hazard Maps.
Seismic Networks
Contact: seis_info@geophys.washington.edu
The Pacific Northwest Seismic Network is a cooperative seismic network observatory housed at the University of Wahington Geophysics Program. Other members include the University of Oregon, Oregon State University Geophysics Group, Cascade Volcano Observatory (CVO), and Battelle Pacific Northwest Laboratory. Together, earthquakes monitoring throughout the Washington-Oregon region is accomplished and research on crustal velocity structure (necessary for accurate earthquake location) is supported.
Site Response
Contact: Arthur Frankel, 303-273-8556
Improving the reliability and usability of detailed seismic hazard maps is a major goal of multidisciplinary studies underway in and with the USGS. Specific objectives include incorporating site response, strong ground motion, and shallow shear velocity in the urban hazard maps for Seattle and the Puget Lowland urban corridor.
Synoptic Plate Maps of Cascadia
Contact: Ralph Haugerud, 206-553-5542
This project provides data and support toward development of synoptic plate maps of the Pacific Northwest. The maps will include the best seismicity catalogs, refined topographic images, gravity, magnetic, and other data. New geologic mapping results will be presented as GIS base images.
Subduction Zone Dynamics
Understanding the tectonic forces that are working in the Puget Sound provides critical information toward determining the magnitude and frequency of large earthquakes there. To get a better insight into the subduction zone processes, travel-time anomalies can be used to model the three dimensional velocity structure of the subducting and overriding plates. Results from this research will allow better modeling of regional strain patterns and the potential of several earthquake sources.
Tsunami Hazard
Contact: Brian Atwater
Once facet of evidence for a very large subduction earthquake in January of 1700 is the arrival of an extensive tsunami in Japan as modelled by Kenji Satake. Brain Atwater spent a year at the Geological Survey fo Hapan studying and modeling tsunami's. His goal is to better understand the 1700 AD tsunami and possible tsunami hazards along the Pacific Coast.
Urban Corridor Hazards
Contact: Ray Wells, 650-329-4933
The Pacific Northwest Urban Corridor is defined as the high-density population area between Eugene, Oregon, and Vancouver, British Columbia. The USGS recognizes that risks from geologic hazards can be lessened by education and strategic planning. This project will create and provide geologic information systems data for use by private and public entities to include in their hazards reduction programs.
Urban Structures
Contact: Erdal Safak, 626-583-7223
Shaking generated by earthquakes in the urban environment damages bridges, highways, office buildings, power transmission lines, gas and water lines, train tracks, storage buildings, airport runways, and the individual home or apartment. The financial cost of interrupted business, in addition to actual repair costs, is a significant part of the earthquake hazard that must be considered. Investigations have begun to more carefully document the seismic response and characteristics of critical structures in Seattle. This data will be used to predict shaking response and to both retrofit existing structures and to design future structures to better withstand the forces from a large earthquake near the urban corridor.
Contacts
Directory of earthquake hazards researchers.
