Wavefield methods to analyze passive ocean bottom seismic data

Abstract

In this study different full waveform techniques was developed for the investigation of seismic ocean bottom single station data. These techniques were applied to data obtained in a pilot ocean bottom experiment in the Tyrrhenian Sea/Italy (TySea experiment) from December 2000 to May 2001. A network of broadband seven ocean bottom seismometers and seven ocean bottom hydrophones was installed above the subducting Ionian plate which descends from Southeast to Northwest. Local and teleseismic earthquakes were recorded by the stations. The newly developed techniques produce very promising results in reconstructing the sea floor structure beneath the stations and in attenuating waveform effects generated by water layer multiples. Additionally the techniques offer a possibility to determine the orientation of free fall ocean bottom seismometers. The main results are: 1. The waveform recorded at the seafloor differs from waveforms recorded at land stations. This is primarily due to multiple reflections in the water layer. These multiple reflections show different patterns on seismometer and hydrophone recordings depending on the seafloor structure. This opens the possibility to constrain the P-wave velocity structure beneath the station by means of a full waveform inversion...