Wide-angle seismic recording from the 2002 Georgia Basin Geohazards Initiative, northwestern Washington and British Columbia
Open-File Report
2003-160
Links
- More information: USGS Index Page (html)
- Document: Report
- Additional Report Piece: Additional Report Piece
- Download citation as: RIS | Dublin Core
Abstract
This report describes the acquisition and processing of shallow-crustal wide-angle seismicreflection and refraction data obtained during a collaborative study in the Georgia Strait, western Washington and southwestern British Columbia. The study, the 2002 Georgia Strait Geohazards Initiative, was conducted in May 2002 by the Pacific Geoscience Centre, the U.S. Geological Survey, and the University of Victoria. The wide-angle recordings were designed to image shallow crustal faults and Cenozoic sedimentary basins crossing the International Border in southern Georgia basin and to add to existing wide-angle recordings there made during the 1998 SHIPS experiment. We recorded, at wide-angle, 800 km of shallow penetration multichannel seismic-reflection profiles acquired by the Canadian Coast Guard Ship (CCGS) Tully using an air gun with a volume of 1.967 liters (120 cu. in.). Prior to this reflection survey, we deployed 48 Refteks onshore to record the airgun signals at wide offsets. Three components of an oriented, 4.5 Hz seismometer were digitally recorded at all stations. Nearly 160,300 individual air gun shots were recorded along 180 short seismic reflection lines. In this report, we illustrate the wide-angle profiles acquired using the CCGS Tully, describe the land recording of the air gun signals, and summarize the processing of the land recorder data into common-receiver gathers. We also describe the format and content of the archival tapes containing the SEGY-formated, common-receiver gathers for the Reftek data. Data quality is variable but the experiment provided useful data from 42 of the 48 stations deployed. Three-fourths of all stations yielded useful first-arrivals to source-receiver offsets beyond 10 km: the average maximum source-receiver offset for first arrivals was 17 km. Six stations yielded no useful data and useful firstarrivals were limited to offsets less than 10 km at five stations. We separately archived our recordings of 86 local and regional earthquakes ranging in magnitude from 0.2 to 4.3 and 16 teleseisms ranging in magnitude 5.5 to 6.5.
Suggested Citation
Brocher, T.M., Pratt, T.L., Spence, G.D., Riedel, M., Hyndman, R.D., 2003, Wide-angle seismic recording from the 2002 Georgia Basin Geohazards Initiative, northwestern Washington and British Columbia: U.S. Geological Survey Open-File Report 2003-160, Report: PDF, 34 p.; Report: TXT, https://doi.org/10.3133/ofr03160.
ISSN: 2331-1258 (online)
Study Area
| Publication type | Report |
|---|---|
| Publication Subtype | USGS Numbered Series |
| Title | Wide-angle seismic recording from the 2002 Georgia Basin Geohazards Initiative, northwestern Washington and British Columbia |
| Series title | Open-File Report |
| Series number | 2003-160 |
| DOI | 10.3133/ofr03160 |
| Year Published | 2003 |
| Language | English |
| Publisher | U.S. Geological Survey |
| Contributing office(s) | Earthquake Science Center |
| Description | Report: PDF, 34 p.; Report: TXT |
| Country | Canada;United States |
| State | British Columbia;Washington |
| Other Geospatial | Georgia Basin;Georgia Strait |
| Additional Online Files (Y/N) | Y |