Development of Hydrophone and Its Aapplications Use in OBS

Abstract:

The seismic wave is translated to T-wave when earthquakes occur below seafloor with a traveling speed of 1500 m/s in the SOFAR channel which centers roughly at 1000 m water depths (Tolstoy and Ewing, 1950). Many studies have shown that hydrophone can be set up in the SOFAR channel to collect acoustic data to investigate plate movement (Fox and Dziak, 1999), seismisity (Fox et.al, 2001), characteristic of T-wave (Park et.al, 2001), seafloor volcanism (Nicolas, 1989), among others. Institute of Earth Sciences of Academia Sinica has been collaborating with Taiwan Ocean Research Institute (TORI) and the Institute of Undersea Technology (IUT) of the National Sun Yat-sen University (NSYSU) to succefully build a new wide-band OBS (Yardbird). We hope that Yardbird is not only an OBS but also a multi-function underwater recording plotform. Therefor we are developing a low-power consumption, inexpensive hydrophone to catch acoustic signals. The protoypte of it has passed a series of tests and got some seismic seafloor data. This paper describes the design goal of hydrophone, component specifications, field data analyzed, and discusses the future directions of instrument development.

Keywords: T-wave; Hydrophone; OBS; acoustic signal

Referance:

1 Fox, C. G. and R. P. Dziak, Intenal deformation of the Gorda Plate observedb y hydroacoustimc onitoring, J . Geophys Res., 104, 17603-17615, 1999.

2 Fox, C. G., H. Matsumoto and T.K.Lau, Monitoring Pacific Ocean seismicity from an autonomous hydrophone array. , J . Geophys. Res., 106,4183-4206, 2001.

3 Nicolas, A., Structures of ophiolites and dynamics of oceanic lithosphere. Dordrecht ; Boston : Kluwer Academic Publishers, 1989.

4. Park, M., R.I. Odom, and D.J. Soukup (2001). Modal scattering: a key to understanding oceanic T-waves, Geophys. Res. Lett. 28, 3401-3404.

5. Tolstoy, I. and M. Ewing (1950). The T phase of shallow-focus earthquakes, Bull. Seismol. Soc. Am. 40, 25-51.