BBOBS
A New Generation of Broadband Ocean Bottom Seismograph

Principal Investigators: Yosio Nakamura and Jay Pulliam

Funding Agency: Texas Advanced Technology Program, Texas Higher Education Coordinating Board

We propose to develop a new generation of ocean bottom seismographs (OBSs) that would be suitable for probing both shallow and deep Earth structure beneath the world's oceans. Ultimately these instruments should be inexpensive to produce, have a broad passband, be capable of deployments lasting one year, and be equipped with three-component sensors. With these capabilities, the resulting seismographs would be useful for basic research into Earth structure and processes, for commercial applications in the oil and gas industry, and for monitoring compliance with the recently-signed Comprehensive Test Ban Treaty (CTBT).

First, oceanic and continental crust are very different, yet we do not know how deep oceanic/continental differences extend. Also, many interesting features of the deep Earth are best viewed from the vantage point of oceanic regions. Second, recent innovations in oil and gas exploration and development include (a) more extensive and sophisticated monitoring of oil fields currently in production and (b) drilling and production in deeper water. Unfortunately, these two innovations cannot currently be combined. OBSs offer a way to monitor changes in not just the three spatial dimensions, but also in a fourth dimension: time. Lastly, the CTBT outlaws the development and testing of nuclear warheads. To ensure compliance with the treaty we must have the capability of detecting and correctly identifying very small seismic events anywhere in the world. Without reliable instrumentation in the oceans it is doubtful that the challenge of monitoring CTBT compliance can be met.

There are significant technical challenges to be overcome in developing such a multi-purpose OBS. To perform the functions outlined above, the broadband BOBS a broad passband and broad dynamic range, not be too sensitive to out-of-plane orientation, the entire broadband BOBS unit must be able to operate on batteries for up to one year and it must have the capacity to store at least a year's worth of data. Thanks to recent advances in the computer technology and telecommunications industries, we believe a workable and inexpensive BBOBS may now be built. Collectively trained on the Earth's interior from the vantage point of its oceans, a fleet of broadband OBSs could be Earth scientists' Hubble telescope.