NAMSS - A NATIONAL ARCHIVE OF MARINE SEISMIC SURVEYS

In 2005, the US Geological Survey introduced a WebInternet-based archive for the dissemination of proprietary and public-domain marine seismic reflection profile data in the US Exclusive Economic Zone (EEZ).

The data in the archive consist principally of (1) USGS data acquired between 1975 and 1990; (2) data acquired by private contractors of 1970 to 1980 vintage that has recently been made available to the public domain; and (3) other public-domain data (government and academic) not available in other archives. The effort has been driven by the urgency to preserve and safeguard data that is at risk of degradation or loss.

The available data are for the most part conventional 2D multichannel airgun seismic reflection profiles acquired and processed to the standards of the 1970's and 1980's. These data were originally intended for offshore oil and gas exploration, and to ensure the safety of associated infrastructure. The surveys were largely limited to the continental shelf EEZ. These data are now available for investigations pertinent to natural hazards assessment (seismic, submarine landslide, tsunami), geologic framework, sediment transport, and other topics of societal relevance. New environmental regulations restricting high-level sound in the oceans virtually preclude these data being reacquired.

Considerable experience has been gained in the effort to catalog, document, reformat, and distribute these data. Tens of thousands of 9-track tapes have been transferred to modern media, and auxiliary data such as observer logs and processed film records digitally scanned. Most of the effort to date has focused on post-stack products, but many data sets are available only as field data. While these pre-stack field data are extremely valuable, the resources required to capture and subsequently reprocess these data are also much greater. A prioritization strategy for salvage of the pre-stack field data is discussed.

The USGS has several partners in this effort, including NSF (Earthscope), Institute for Crustal Studies at UC Santa Barbara, the IRIS Data Management Center, and Minerals Management Service. The ultimate objective is to provide a comprehensive geophysical data repository, accessible on-line, with a graphical search and retrieval interface available to teachers, researchers, and the general public.