A future for drifting seismic networks

Frederik J Simons¹, Guust Nolet², Jeff M. Babcock³, Russ E. Davis³, John A. Orcutt³

1 Earth Sciences Department
University College London
London, WC1E 6BT, UK

2 Geosciences Department
Princeton University
Princeton NJ 08544, USA

3 Institute of Geophysics and Planetary Physics
Scripps Institution of Oceanography
La Jolla, CA 92093, USA

Abstract

In the last few decades seismologists have mapped out elastic wavespeeds of the Earth's interior with often perplexing if not always uncontested detail. Earthquake sources used in seismic tomography lie mostly on plate boundaries; receivers mostly on dry land. The uneven coverage resulting from this fundamentally inadequate source-station distribution leaves large volumes inside the Earth entirely unsampled. Placing seismic stations on the ocean bottom is often touted as the only solution. The MERMAID project (Mobile Earthquake Recorder in Marine Areas by Independent Divers) is a radical low-cost alternative that uses passively drifting autonomous hydrophones with a now proven potential to record hundreds of distant earthquakes over their projected life span.

Figures

1. Figure 01 Example of poor resolution of mantle structure in the southern hemisphere and elsewhere due to the absence of seismic stations in the ocean.
   
2. Figure 02 The MERMAID-001 prototype. The hydrophone protrudes from the middle right.
   
3. Figure 03 A P wave from a magnitude 6.0 earthquake at 46 degrees detected at 700 m depth by the hydrophone onboard MERMAID-001.