Transpacific Detection by Underwater Sound of Myojin Volcanic Explosions

Dietz, R. S.; Sheehy, M. J.

doi:10.5928/kaiyou1942.9.53

Cited by 13 publications

(12 citation statements)

References 6 publications

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“…Several accounts of low-frequency hydroacoustic signals originating from submarine volcanoes exist in the literature (e.g. Dietz and Sheehy, 1954;Snodgrass and Richards, 1956;Caplan-Auerbach et al, 2001), and in at least one case hydrophone recordings of these low-frequency rumbles have led to the detection and location of a previously unknown volcanic centre, the aptly named Rumble III (Kibblewhite, 1966). In the West Indies we can easily recognize T-phase and distinguish it from other types of seismic signal by measuring the velocity of propagation as the waves travel from island to island.…”

Section: Detection Of T-phase From Kick 'Em Jennymentioning

confidence: 99%

Volcanic and Scientific Activity at Kick ?em Jenny Submarine Volcano 2001?2002: Implications for Volcanic Hazard in the Southern Grenadines, Lesser Antilles

2005

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Kick 'em Jenny submarine volcano, 8 km north of Grenada, has erupted at least 12 times since it was first discovered in 1939, making it the most frequently active volcano in the Lesser Antilles arc. The volcano lies in shallow water close to significant population centres and directly beneath a major shipping route, and as a consequence an understanding of the eruptive behaviour and potential hazards at the volcano is critical. The most recent eruption at Kick 'em Jenny occurred on December 4 2001, and differed significantly from past eruptions in that it was preceded by an intensive volcanic earthquake swarm. In March 2002 a multi-beam bathymetric survey of the volcano and its surroundings was carried out by the NOAA ship Ronald H Brown. This survey provided detailed three-dimensional images of the volcano, revealing the detailed morphology of the summit area. The volcano is capped by a summit crater which is breached to the northeast and which varies in diameter from 300 to 370 m. The depth to the summit (highest point on the crater rim) is 185 m and the depth to the lowest point inside the crater is 264 m. No dome is present within the crater. The crater and summit region of Kick 'em Jenny are located at the top of an asymmetrical cone which is about 1300 m from top to bottom on its western side. It lies within what appear to be the remnants of a much larger arcuate collapse structure. An evaluation of the morphology, bathymetry and eruptive history of the volcano indicates that the threat of eruption-generated tsunamis is considerably lower than previously thought, mainly because the volcano is no longer thought to be growing towards the surface. Of more major and immediate concern are the direct hazards associated with the volcano, such as ballistic ejecta, water disturbances and lowered water density due to degassing.

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Section: Detection Of T-phase From Kick 'Em Jennymentioning

confidence: 99%

Volcanic and Scientific Activity at Kick ?em Jenny Submarine Volcano 2001?2002: Implications for Volcanic Hazard in the Southern Grenadines, Lesser Antilles

2005

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“…2) showed the volcano to be an elongate, twin-summit edifice located 8-12 km ENE of the Bayonnaise Rocks, jagged spires of hypersthene-augite basalt protruding several meters above sea level . The area of closed contours between the Bayonnaise Rocks and Myojinsho suggested the existence of a caldera, but there was disagreement as to whether Myojinsho was located along the caldera rim (Morimoto and Ossaka 1955) or formed a central cone within the caldera (Dietz and Sheehy 1954).…”

Section: Pre-eruption Bathymetrymentioning

confidence: 99%

“…A simplified chronology of the eruption is presented in Table 2; more information is available in Dietz and Sheehy (1954), Morimoto and Ossaka (1955), and Morimoto (1960) and in the many references cited in those reports. Dietz (1954) presented a brief, popularized account of the eruption, accompanied by high-quality photographs.…”

Section: -1953 Eruptionmentioning

confidence: 99%

Tephra dispersal from Myojinsho, Japan, during its shallow submarine eruption of 1952-1953

Fiske¹,

Cashman

Shibata³

et al. 1998

Bulletin of Volcanology

117

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A new and detailed bathymetric map of the Myojinsho shallow submarine volcano provides a framework to interpret the physical volcanology of its 1952-1953 eruption, especially how the silicic pyroclasts, both primary and reworked, enlarged the volcano and were dispersed into the surrounding marine environment. Myojinsho, 420 km south of Tokyo along the Izu-Ogasawara arc, was the site of approximately 1000 phreatomagmatic explosions during the 12.5month eruption. These explosions shattered growing dacite domes, producing dense clasts that immediately sank into the sea; minor amounts of pumice floated on the sea surface after some of these events. The Myojinsho cone has slopes of almost precisely 217 in the depth range 300-700 m.We interpret this to be the result of angle-of-repose deposition of submarine pyroclastic gravity flows that traveled downslope in all directions. Many of these gravity flows resulted from explosions and associated dome collapse, but others were likely triggered by the remobilization of debris temporarily deposited on the summit and steep upper slopes of the cone. Tephra was repeatedly carried into air in subaerial eruption columns and fell into the sea within 1-2 km of the volcano's summit, entering water as deep as 400 m. Because the fall velocity of single particles de-creased by a factor of F30 in passing from air into the sea, we expect that the upper part of the water column was repeatedly choked with hyperconcentrations of fallout tephra. Gravitational instabilities within these tephra-choked regions could have formed vertical density currents that descended at velocities greater than those of the individual particles they contained. Upon reaching the sea floor, many of these currents probably continued to move downslope along Myojinsho's submarine slopes. Fine tephra was elutriated from the rubbly summit of the volcano by upwelling plumes of heated seawater that persisted for the entire duration of the eruption. Ocean currents carried this tephra to distal areas, where it presumably forms a pyroclastic component of deep-sea sediment.

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“…Although underwater explosions represent 20 % of the observed volcanic tsunamis, the tsunamis hazards related to such events are generally poorly documented and often neglected (Freundt et al 2007). Best studied examples are (1) the Myojin-Sho (Japan) eruption in 1952, which generated waves with amplitudes up to 1.4 m high at 130 km from the volcano (Dietz and Sheehy 1954), (2) the numerous small tsunamis reported and sometimes photographed during explosions of Kavachi volcano in the Solomon Islands (Johnson and Tuni 1987) and (3) the Kick'em Jenny volcano in the Caribbean Sea, which caused 2-m tsunami waves at Grenada Island in 1939 (Smith and Shepherd 1993). Local tsunami waves generated by underwater explosions in the Krakatau caldera were described and photographed by Stehn (1929).…”

Section: Source Mechanisms In Volcanic Systemsmentioning

confidence: 99%

Volcanic tsunami: a review of source mechanisms, past events and hazards in Southeast Asia (Indonesia, Philippines, Papua New Guinea)

et al. 2013

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Southeast Asia has had both volcanic tsunamis and possesses some of the most densely populated, economically important and rapidly developing coastlines in the world. This contribution provides a review of volcanic tsunami hazard in Southeast Asia. Source mechanisms of tsunami related to eruptive and gravitational processes are presented, together with a history of past events in the region. A review of available data shows that many volcanoes are potentially tsunamigenic and present often neglected hazard to the rapidly developing coasts of the region. We highlight crucial volcanic provinces in Indonesia, the Philippines and Papua New Guinea and propose strategies for facing future events.

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Transpacific Detection by Underwater Sound of Myojin Volcanic Explosions

Cited by 13 publications

References 6 publications

Volcanic and Scientific Activity at Kick ?em Jenny Submarine Volcano 2001?2002: Implications for Volcanic Hazard in the Southern Grenadines, Lesser Antilles

Volcanic and Scientific Activity at Kick ?em Jenny Submarine Volcano 2001?2002: Implications for Volcanic Hazard in the Southern Grenadines, Lesser Antilles

Tephra dispersal from Myojinsho, Japan, during its shallow submarine eruption of 1952-1953

Volcanic tsunami: a review of source mechanisms, past events and hazards in Southeast Asia (Indonesia, Philippines, Papua New Guinea)

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