Nonindustrial Marine Reflection Seismology Capabilities and U.S. Planning for the Next Decade
Authors: Shipley Thomas H. , Moore Gregory F. 
Published: October 2008

In the United States and worldwide, non-industrial (mainly academic) marine reflection seismology acquisition peaked in the early 1980's. The only active large multichannel reflection system deployed in the U.S. is on the R/V Maurice Ewing of Columbia University. Even though it is used only four months per year in this mode it continues to provide scientists the ability to conduct experiments in regions of the world not typically served by commercial operators. It provides a unique platform for scientists to work with new acquisition techniques and train students. Other countries experience similar usage levels for their acquisition systems. Combined worldwide activities of primarily academic systems are about 18 months per year for large MCS operations spread across 10 or more ships.

Scientific programs have included 3-D studies of active oceanic ridge crest magma chambers and fluid flow along the plate boundary faults beneath accretionary margins. Twodimensional surveys include studies of Jurassic stratigraphy in the deep oceans, architecture of oceanic plateaus, cross sections of major subduction zones, and the structure of thickly sedimented passive margins.

Scientific research objectives are well developed for the next decade, defining a growing role for sophisticated survey techniques at significantly smaller spatial scales. A recent workshop held to review academic seismic acquisition in the U.S. revealed a significant gap between the needs of the community and existing levels and types of acquisition that are realistically available. To achieve the stated scientific goals for the next decade will require more capable 3-D and 4-C systems. This will require a coordinated international academic response and cooperation with commercial contractors. The academic marine Geoscience programs need to foster fundamental changes in their operations, partnerships and budget levels to meet the challenges of the next decade.

Introduction

In the United States, scientific planning activities within the marine geology and geophysics (MG&G) and related communities have identified specific scientific goals for the next decade that require access to seismic acquisition facilities. Over the next decade the academic scientists will need high fidelity subsurface images of compressional and shear energy at all scales. At the same time, the number of academic Earth scientists and their students involved in marine data acquisition continues to drop. The declining numbers are due to the difficulty in using existing academic equipment, the lack of easy access to data collected by other investigators and funding levels.

History of U.S. Seismic Acquisition

With the advent of seismic profiling in the 1960's and particularly the invention of the compressed air "gun" at Lamont- Doherty Earth Observatory (Lamont), seismic profiles were collected routinely into the mid-1970's using a towed single channel hydrophone array (SCS). The results were millions of kilometers of profiles of the thin sediments and sedimentary structures above the oceanic crust and continental and island arc margins around the world. In the late 1970's, the earlier SCS methods were upgraded to digital recording and became important for a variety of higher spatial resolution problems associated with paleoceanography and neotectonics when used in conjunction with new seafloor swath mapping tools.