Publication Date:
2018-02-08
Description:
Bottom shots have been used for a number of years in seismic studies on the ocean floor. Most experiments utilized
explosives as the energy source, though researchers have recognized the usefulness of collapsing water voids to
produce seismoacoustic signals. Implosive sources, however, suffered generally from a lack of control of source
depth. We present a new experimental tool, called SEEBOSEIS, to carry out seismic experiments on the seafloor
utilizing hollow glass spheres as controlled implosive sources. The source is a 10-inch BENTHOS float with
penetrator. Inside the sphere we place a small explosive charge (two detonators) to destabilize the glass wall. The
time of detonation is controlled by an external shooting device. Test measurements on the Ninetyeast Ridge, Indian
Ocean, show that the implosive sources can be used in seismic refraction experiments to image the subbottom P-
wave velocity structure in detail beyond that possible with traditional marine seismic techniques. Additionally, the
implosions permit the efficient generation of dispersed Scholte waves, revealing upper crustal S-wave velocities.
The frequency band of seismic energy ranges from less than 1 Hz for Scholte modes up to 1000 Hz for diving
P-waves. Therefore, broadband recording units with sampling rates
〉2000 Hz are recommended to sample the
entire wave field radiated by implosive sources.
Type:
Article
,
PeerReviewed
Format:
text
