Recent Results in Submarine Geophysics

Ewing, Maurice; Woollard, George P.; Vine, Allyn C.; Worzel, J. Lamar

doi:10.1130/0016-7606(1946)57[909:rrisg]2.0.co;2

Cited by 107 publications

(26 citation statements)

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“…Considerable progress was made during WWII toward understanding the propagation of sound in the ocean, in particular with the discovery of the existence of the SOFAR low-velocity channel. These results were first summarized after the war by Ewing et al (1946) and expanded from both a theoretical and an experimental standpoint by Ewing and Worzel (1948), Pekeris (1948), and Worzel and Ewing (1948). A model for the reverberation of sound in the channel was proposed independently by Brekhovskikh (1949), following the experiments of Rozenberg (1949).…”

Section: Early Observations Of T Phases" a Historical Perspectivementioning

confidence: 77%

T-phase Stations for the International Monitoring System of the Comprehensive Nuclear-Test Ban Treaty: A Global Perspective

Okal

2001

Seismological Research Letters

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Section: Early Observations Of T Phases" a Historical Perspectivementioning

confidence: 77%

T-phase Stations for the International Monitoring System of the Comprehensive Nuclear-Test Ban Treaty: A Global Perspective

Okal

2001

Seismological Research Letters

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“…For this reason, and in order to investigate their sources, we now turn to the T waves generated by the PNG aftershocks. We recall that T waves are acoustic (sound) waves generated in the water column of the world's oceans by a variety of sources including oceanic earthquakes, and efficiently propagated to extreme distances on account of the channeling properties of the SOFAR waveguide (EWING et al, 1946). They can be recorded either at sea on hydrophones or by seismometers deployed close to shorelines, through their conversion to seismic waves when they hit the shore (e.g., OKAL, 2001a).…”

Section: T -Wave Records Of the 09:02 Eventmentioning

confidence: 99%

T Waves from the 1998 Papua New Guinea Earthquake and its Aftershocks: Timing the Tsunamigenic Slump

Okal

2003

Pure and Applied Geophysics

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T waves recorded at hydrophone and seismic stations following the Papua New Guinea earthquake of 17 July 1998 and its aftershocks show that a small event at 09:02 GMT featured source properties incompatible with an elastic dislocation of appropriate body-wave magnitude (m b ¼ 4:4). These include an exceptional duration (47 s at the Wake Island hydrophone station WK31), a spectrum rich in high frequencies (7 to 12 Hz), and a generally low spectral amplitude. These characteristics can be explained by the model of an underwater slump, accelerating from a standstill and eventually slowing down. The relocation of the 09:02 event is compatible with its location within an amphitheater inside which shipboard cruises in 1998 and 1999 documented the presence of a 4 -km 3 geologically fresh slump. We propose that the slump took place at 09:02 on 17 July 1998, i.e., 13 minutes after the mainshock, and that it generated the locally catastrophic tsunami, whose properties (amplitude and distribution of runup; timing) could not be explained by a dislocation model.

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“…Ewing et al (1946) speculated that some of underwater sounds observed by SOFAR hydrophones might be from submarine volcanic activities, and suggested that detection and location of submarine volcanoes would be one of the applications of the SOFAR monitoring. The first detailed study on the underwater sounds associated with submarine volcanic activities was done by Dietz and Sheehy (1954).…”

Section: Discussionmentioning

confidence: 99%

T Waves Associated with Submarine Volcanic Eruptions in the Marianas Observed by Ocean Bottom Seismographs.

et al. 1993

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In September and December of 1989, swarms of T waves were observed by ocean bottom seismographs (BSOBS) off the Boso Peninsula of Japan, by a SOFAR hydrophone array near Wake Island, and by a station at Rangiroa. Using arrival times observed by these networks, the source location of the T waves was determined to be in the northern Marianas, where submarine eruptions had been observed frequently in recent years.The T waves were not accompanied by corresponding body waves. The T waves had shorter duration (from a few to ten seconds) and higher prominent frequency than those of tectonic earthquakes which also occurred in the northern Marianas. The amplitude variation of the T waves observed by BSOBS showed a different pattern from those from tectonic earthquakes. This is a manifestation of a difference in the spectral contents between them. The spectra of these T waves showed conspicuous harmonic peaks. These characteristics are similar to those of volcanic T waves as previously reported. Therefore we concluded that they are excited by submarine volcanic eruptions.From the detailed analysis of the T wave events, this volcanic activity is considered to proceed through three stages: the first which was not so explosive, the second which was composed of intermittent explosive eruptions, and the third which was small and similar to the first. The observed fundamental frequencies of the T waves varied with time. This could be caused by changes in the eruption site or in the size of the area where reverberations occurred.

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Recent Results in Submarine Geophysics

Cited by 107 publications

References 0 publications

T-phase Stations for the International Monitoring System of the Comprehensive Nuclear-Test Ban Treaty: A Global Perspective

T-phase Stations for the International Monitoring System of the Comprehensive Nuclear-Test Ban Treaty: A Global Perspective

T Waves from the 1998 Papua New Guinea Earthquake and its Aftershocks: Timing the Tsunamigenic Slump

T Waves Associated with Submarine Volcanic Eruptions in the Marianas Observed by Ocean Bottom Seismographs.

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