Volcanoes as possible indicators of tectonic stress orientation—Aleutians and Alaska

Nakamura, Kazuaki; and, Klaus Jacob; Davies, John N.

doi:10.1029/me001p0463

Cited by 44 publications

(50 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…They concluded that the stress regime generally changes from compressional in the thrust zone close to the trench to shear along the volcanic arc landward to tensional in the back arc. They proposed that flank eruptions for polygenetic volcanoes can be regarded as the result of a large-scale natural magmafracturing experiment [Nakamura et al, 1977] Earthquakes that continued to occur beneath Lava Point and the summit caldera from August 1996 to December 1998 may represent continued stress adjustments to the March 1996 intrusion. The apparent shoaling of hypocenters beneath the caldera suggests that this area may be too hot to support brittle failure below a depth of 3-4 km.…”

Section: Interpretation Of the March 1996 Swarm And Future Challengesmentioning

confidence: 99%

Ground deformation associated with the March 1996 earthquake swarm at Akutan volcano, Alaska, revealed by satellite radar interferometry

Lü¹,

Wicks²,

Power³

et al. 2000

J. Geophys. Res.

View full text Add to dashboard Cite

Abstract. In March 1996 an intense swarm of volcano-tectonic earthquakes (-3000 felt by local residents, A/max-5.1, cumulative moment of 2.7 x 10 •8 N m) beneath Akutan Island in the Aleutian volcanic arc, Alaska, produced extensive ground cracks but no eruption of Akutan volcano. Synthetic aperture radar interferograms that span the time of the swarm reveal complex island-wide deformation: the western part of the island including Akutan volcano moved upward, while the eastern part moved downward. The axis of the deformation approximately aligns with new ground cracks on the western part of the island and with Holocene normal faults that were reactivated during the swarm on the eastern part of the island. The axis is also roughly parallel to the direction of greatest compressional stress in the region. No ground movements greater than 2.83 cm were observed outside the volcano's summit caldera for periods of 4 years before or 2 years after the swarm. We modeled the deformation primarily as the emplacement of a shallow, east-west trending, north dipping dike plus inflation of a deep, Mogi-type magma body beneath the volcano. The pattern of subsidence on the eastern part of the island is poorly constrained. It might have been produced by extensional tectonic strain that both reactivated preexisting faults on the eastern part of the island and facilitated magma movement beneath the western part. Alternatively, magma intrusion beneath the volcano might have been the cause of extension and subsidence in the eastern part of the island. We attribute localized subsidence in an area of active fumaroles within the Akutan caldera, by as much as 10 cm during 1992-1993 and 1996-1998, to fluid withdrawal or depressurization of the shallow hydrothermal system.

show abstract

Section: Interpretation Of the March 1996 Swarm And Future Challengesmentioning

confidence: 99%

Ground deformation associated with the March 1996 earthquake swarm at Akutan volcano, Alaska, revealed by satellite radar interferometry

Lü¹,

Wicks²,

Power³

et al. 2000

J. Geophys. Res.

View full text Add to dashboard Cite

show abstract

“…Secondly, the gradient of the crack normal stress can contribute to the driving force for propagation (e.g., Takada, 1989). Many investigations have been done on the influence of the external stress generated by tectonic forces (e.g., Nakamura, 1977), topography (e.g., McGuire and Pullen, 1989) and pre-existing magma bodies (e.g., Takada, 1994a).…”

Section: Introductionmentioning

confidence: 99%

Analog experiments on magma-filled cracks: Competition between external stresses and internal pressure

et al. 2014

View full text Add to dashboard Cite

We have performed two series of analog experiments using gelatin to study the propagation of liquid-filled cracks in stressed medium. The first series was designed to study the competition between the external stress and the liquid excess pressure in controlling the propagation direction. We systematically controlled the external stress and the liquid excess pressure by changing the surface load and the liquid volume. An ascending crack progressively deflected to be perpendicular to the maximum tensile direction of the external stress. The degree of deflection depends on the ratio of the shear stress on a crack plane to the average liquid excess pressure. More deflection was observed for a crack with a larger ratio. No significant deflection was observed for the ratio less than 0.2. The volcanic activity in a compressional stress field might be understood in the context of this competition. The first series also demonstrated the importance of the gradient of the crack normal stress as a driving force for propagation. The vertical gradient of the gravitational stress generated by a mountain load can control the emplacement depth of magmas, and it might lead to the evolution of eruption style during the lifetime of a volcano. The second series was designed to study the three-dimensional interaction of two parallel buoyancy-driven cracks. The deflection of the second crack takes place, when the ratio of the shear stress generated by the first one to the average excess pressure of the second crack is larger than 0.2. If the second crack reaches the first one, the interaction can lead to the coalescence of two cracks. It has directivity: the region of coalescence extends more in the direction perpendicular to the first crack than in the direction parallel to it. It reflects the stress field around the first crack. This directivity might cause a characteristic spatial variation of magma chemistry through magma mixing.

show abstract

“…Consequently, a weak strength zone (WSZ) is constructed around the invaded magmatic fluid, which tends to elongate in the maximum tectonic stress direction, as pointed out by NAKAMURA (1977) andHILL (1977). Swarm activity occurs in the WSZ, showing the epicentral zone trending in the maximum stress direction.…”

Section: Discussionmentioning

confidence: 99%

Seismicity survey with pop-up-type OBS array in the western part of Sagami Bay.

1989

View full text Add to dashboard Cite

Eight pop-up-type ocean bottom seismometers (OBS's) were deployed in western Sagami Bay, central Japan, for about one month in order to investigate the seismicity in the northernmost part of the Philippine Sea plate, where seismic activity has been intense for the past decade. About 100 earthquakes were located in the western Sagami Bay region, clustering into mainly three groups. The most active group is in the area off the east coast of the central Izu Peninsula, where swarm activity has occurred since late 1978. The epicentral distribution of events of this group is aligned WNW-ESE and the focal depth range is shallower than 15 km. A small cluster was located 5 km to the south of the main alignment, with focal depths shallower than 10 km located beneath the submarine volcano Nishi-ChigasakiKaikyu. The second group is located west of Izu-Oshima Island, where foreshocks of the 1978 Izu-Oshima-kinkai earthquake occurred. The epicenters in this group are aligned NW-SE, showing en echelon pattern with the first group. Their focal depths are determined to be shallower than 5 km. The third group is roughly located between the Izu-Oshima and Niijima Islands, but could not be located precisely because these events are out of the OBS array. Swarmlike occurrences were found for the second and third groups. Particularly in the second group, two burst-type activities were found in the observational period. The directions of the epicenter alignments of the first and the second group are in agreement with the maximum tectonic stress direction, crossing the fault traces of the major earthquakes occurring there. This seismicity pattern is interpreted as a result of the presence of a "weak strength zone" caused by magmatic intrusion along the maximum tectonic stress direction.

show abstract

Volcanoes as possible indicators of tectonic stress orientation—Aleutians and Alaska

Cited by 44 publications

References 1 publication

Ground deformation associated with the March 1996 earthquake swarm at Akutan volcano, Alaska, revealed by satellite radar interferometry

Ground deformation associated with the March 1996 earthquake swarm at Akutan volcano, Alaska, revealed by satellite radar interferometry

Analog experiments on magma-filled cracks: Competition between external stresses and internal pressure

Seismicity survey with pop-up-type OBS array in the western part of Sagami Bay.

Contact Info

Product

Resources

About