Volcano-tectonic seismicity at Unzen Volcano, Japan, 1985–1999

Umakoshi, Keisuke; Shimizu, Hiroshi; Matsuwo, Norimichi

doi:10.1016/s0377-0273(01)00238-4

Cited by 81 publications

(43 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Prior to the eruption, seismicity was high toward the western part of the graben and low on the eastern segment, as shown in Fig. 2 (Umakoshi et al, 2001).…”

Section: Introductionmentioning

confidence: 93%

“…The depths of the sources increased towards the west from the lava dome. Umakoshi et al (2001) determined the cut-off depth of the earthquake distribution from an E-W cross-section and observed that the average depth of the distribution decreased eastwards towards the lava dome. They also determined the variations in the focal mechanism with depth; these variations suggest the presence of high-temperature, ductile, and low-Q, bodies below the cut-off depth.…”

Section: Introductionmentioning

confidence: 99%

“…of hypocenter distribution and pressure sources (Kohno et al, 2008). The dots denote the hypocenters obtained for the period 1985-1999 by Umakoshi et al (2001). The grey circles are the pressure sources (Umakoshi et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Seismic reflection survey of the crustal structure beneath Unzen volcano, Kyushu, Japan

et al. 2012

View full text Add to dashboard Cite

Unzen volcano is located in the western part of Kyushu, Japan. We carried out a seismic re ection survey at Unzen volcano in order to elucidate the structure of the volcano. Although the survey was conducted in a volcanic area under dif cult conditions, such as arti cial noises and a complex structure, we were able to resolve the structure beneath the pro le using vibrator sources and a large number of stacking signals. The processed depth sections con rmed that Unzen volcano developed in a graben structure, as has been suggested in other geological studies. We imaged many subsurface normal faults shallower than 1 km. These faults, mostly covered with volcanic lava and deposits, were identi ed at the surface. Strong re ectors were found at a depth of approximately 3 km. They were located just above the pressure source of the latest eruption, as inferred from geodetic data. The geometric relationship between the re ection image, the pressure source location, and the lava dome suggests that the conduit from the lava dome could connect to the magma chamber located 4 km away from the lava dome.

show abstract

“…Prior to the eruption, seismicity was high toward the western part of the graben and low on the eastern segment, as shown in Fig. 2 (Umakoshi et al, 2001).…”

Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Seismic reflection survey of the crustal structure beneath Unzen volcano, Kyushu, Japan

et al. 2012

View full text Add to dashboard Cite

show abstract

“…Both of the latter types of events occurred for several days, slowly decreasing in number. Umakoshi et al (2001) also noted that volcano-tectonic seismicity at Unzen Volcano, Japan, was at a high level before the appearance of the lava dome on May 20, 1991, and that with the onset of lava effusion, volcano-tectonic earthquakes virtually ceased to occur within a radius of 5 km from the crater.…”

Section: Comparison With Seismicity That Was Observed At Other Volcanoesmentioning

confidence: 95%

Seismicity of an andesitic volcano during block-lava effusion: Volcán de Colima, México, November 1998–January 1999

et al. 2005

View full text Add to dashboard Cite

The block-lava effusion at Volcµn de Colima, MØxico began on November 20, 1998, after 12 months of seismic activity, and ended about 80 days later. Three types of seismic events were observed during the lava effusion. Volcano-tectonic earthquakes occurred mainly at the very beginning and after the termination of lava effusion. Explosion earthquakes occurred frequently during the period of the maximum rate in lava effusion. The remainder of the seismic signals were associated with pyroclastic flows and rockfalls from the lava dome. These latter signals increased sharply in number at the onset of lava effusion. The rate of occurrence remained high when the lava discharge rate decreased but gradually decreased after the termination of lava effusion. Maximum daily durations of seismic signals are proportional to the daily volumetric output of lava, indicating the dependence of the number of pyroclastic flows on the rate of lava output. A log-log plot of seismic signal duration vs. number of events with this duration displays a linear relationship. The short-period seismic signals can be divided into three categories based on duration: short events with durations less than 100 s; intermediate events with durations between 100 and 250 s; and long events with durations longer than 250 s. We infer that long events correspond to pyroclastic flows with mean deposit volume $210 5 m 3 , and intermediate events represent pyroclastic flows with mean deposit volume $110 3 m 3 .

show abstract

“…Stress changes associated with magma migration and more in general with the dynamics of magma chambers and hydrothermal systems are causally linked to these earthquakes. Hence retrieving the stress field pattern in volcanoes has important implications in studying their dynamics and the interaction with the regional tectonic stress field (Umakoshi et al, 2001;Pedersen and Sigmundsson, 2004;Segall, 2013;Cannavò et al, 2014;D'Auria et al, 2014a,b).…”

Section: Introduction Theoretical Background To Stress Field Inversionmentioning

confidence: 99%

Determining the Stress Field in Active Volcanoes Using Focal Mechanisms

et al. 2016

View full text Add to dashboard Cite

Volcano-tectonic seismicity at Unzen Volcano, Japan, 1985–1999

Cited by 81 publications

References 7 publications

Seismic reflection survey of the crustal structure beneath Unzen volcano, Kyushu, Japan

Seismic reflection survey of the crustal structure beneath Unzen volcano, Kyushu, Japan

Seismicity of an andesitic volcano during block-lava effusion: Volcán de Colima, México, November 1998–January 1999

Determining the Stress Field in Active Volcanoes Using Focal Mechanisms

Contact Info

Product

Resources

About