Pacific Coastal & Marine Science Center
National Archive of Marine Seismic Surveys
The purpose of this Website is to provide up-to-date information on the data recovery effort and links to on-line resources to access data.
Marine Seismic reflection profile data acquired originally for purposes of oil and gas exploration and development within the US EEZ represent a national scientific resource of inestimable value. Although the commercial value of these data has diminished due to technological advances and offshore development moratoria, the value to current and future scientific endeavors continues to be very high.
Recently, commercial owners of large data holdings offshore the western US have offered to transfer these data to the public domain. Recognizing the value of these data, the USGS is committed to safekeeping on behalf of the academic community and the nation any data that may otherwise be lost, and free and open access to that data.
High-quality seismic reflection data are essential to geological investigation of the offshore. Over the past thirty years the USGS has acquired approximately 12,000 km of 2D data off the west coast of the United States. During this same period the petroleum exploration industry acquired probably 30 to 50 times that amount. To date, these data have been proprietary and available for publishable research only with significant restrictions. Although the commercial value of these data has diminished as a result of technological advances and offshore development moratoria, these data continue to have great relevance and value to current and future scientific research efforts. The value and risk of loss of these data was recently the subject of a National Research Council report "Geoscience Data and Collections: National Resources in Peril" by the Committee on the Preservation of Geoscience Data and Collections, Committee on Earth Resources.
Recently, two companies with perhaps the largest holdings of proprietary data off the US west coast, WestemGeco and Chevron, have offered to transfer more than 250,000 km to the USGS for the purpose of making those data publicly available for research and educational purposes. Extension of these offers to include data offshore Alaska and the east coast of the U.S. is under discussion. The data being offered are for the most part conventional 2D multichannel airgun seismic reflection acquired and processed according to standards of the mid 1970's and early 1980's. The data commonly were acquired using a 5-to-25 element tuned airgun source totaling 1,000 to 3,000 cubic inches; 24-fold to 48-fold stacking; 25-to-50 meter CDP interval; 6 second recording with 4 msec sampling; processed through stack and post-stack migration. The surveys were generally limited to the continental shelf, extending up to 150 miles offshore southern California. Line spacing is dense off southern California, and becomes sparser to the north.
Cataloging, documenting, reformatting, and providing access to these data will require a multi-year effort. Tens of thousands of digital 9-track tapes will be transferred to modern media, and auxiliary data (such as observer logs and processed film records) will be scanned. The available processed data (post-stack and migration) for all the data sets will be reformatted and cataloged on-line. However, a much larger quantity of data (25- to 50 times greater) exists in the form of original field recordings (pre-stack) for each data set. While these pre-stack field data are also extremely valuable, the resources required to capture and subsequently reprocess these data are correspondingly large. A prioritization strategy for salvage of the pre-stack data must be developed.
The USGS has several partners in this effort, including NSF (Earthscope), Institute for Crustal Studies at UC Santa Barbara, the IRIS Data Management Center, University of Southern California, and Bureau of Ocean Energy Management. The ultimate objective is the creation of a comprehensive geophysical data repository accessible on-line, with a graphical search and retrieval interface that would be available to teachers and researchers.
For more information, contact Patrick Hart.