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Kozushima

Photo of this volcano
  • Japan
  • Izu Volcanic Arc
  • Composite | Lava dome(s)
  • 838 CE
  • Country
  • Volcanic Province
  • Landform | Volc Type
  • Last Known Eruption
  • 34.219°N
  • 139.153°E

  • 572 m
    1877 ft

  • 284030
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number


Most Recent Bulletin Report: October 1995 (BGVN 20:10) Citation IconCite this Report

Earthquake swarm ends in mid-October

As reported in BGVN 20:09, on 6 October a M 5.6 earthquake occurred adjacent to Kozu-shima and a seismic swarm followed for the next few days. After that, seismic events continued but decreased toward the end of October; in total, during October there were 246 felt earthquakes.

Information Contacts: Volcanological Division, Seismological and Volcanological Department, Japan Meteorological Agency (JMA), 1-3-4 Ote-machi, Chiyoda-ku, Tokyo 100 Japan.

The Global Volcanism Program has no Weekly Reports available for Kozushima.

Bulletin Reports - Index

Reports are organized chronologically and indexed below by Month/Year (Publication Volume:Number), and include a one-line summary. Click on the index link or scroll down to read the reports.

04/1991 (BGVN 16:04) Earthquake swarm but no surface activity

10/1991 (BGVN 16:10) Earthquake swarm N of island

01/1992 (BGVN 17:01) Earthquake swarm follows nearby Nii-jima seismicity; no surface activity observed

04/1992 (BGVN 17:04) Two seismic swarms; no surface changes evident

05/1992 (BGVN 17:05) Continued seismic swarms

06/1992 (BGVN 17:06) Earthquake and aftershocks

08/1992 (BGVN 17:08) Weak seismic swarm; surface activity unchanged

09/1992 (BGVN 17:09) Weak earthquake swarm

10/1992 (BGVN 17:10) Earthquake swarm but no surface changes evident

03/1993 (BGVN 18:03) Earthquake swarm on 25 March; no surface anomalies

08/1993 (BGVN 18:08) Earthquake swarms

09/1995 (BGVN 20:09) Strong earthquake swarm in early October

10/1995 (BGVN 20:10) Earthquake swarm ends in mid-October




Information is preliminary and subject to change. All times are local (unless otherwise noted)


April 1991 (BGVN 16:04) Citation IconCite this Report

Earthquake swarm but no surface activity

An earthquake swarm (M <= 4.0) occurred from 2100 to 2400 on 23 April, with seismicity gradually returning to normal levels by the following day. Many of the earthquakes were felt by residents (to JMA intensity IV). Swarm events were centered from the W coast to 20 km SW of the island (figure 1), at 0-10 km depth. No surface activity was reported.

Figure (see Caption) Figure 1. Epicenter map (top) and space/time diagram (bottom) showing seismicity around Kozu-shima and Nii-jima volcanoes, January 1991-June 1992. Courtesy of JMA.

Information Contacts: JMA.


October 1991 (BGVN 16:10) Citation IconCite this Report

Earthquake swarm N of island

An earthquake swarm occurred 24-25 October in the sea 7 km N of Kozu-shima (figure 1). The largest shocks (M 4.9) were recorded at 1746 and 1754 on the 24th. Changes in surface activity were not observed on the island or in the epicentral area. The seismicity was the first for the area since 23 April . . . .

Information Contacts: JMA.


January 1992 (BGVN 17:01) Citation IconCite this Report

Earthquake swarm follows nearby Nii-jima seismicity; no surface activity observed

On 26-27 January, three weeks after an earthquake swarm centered ~10 km NE of the volcano, another swarm was recorded a few kilometers E of Kozu-shima (figure 1). The 26-27 January swarm's two largest shocks, M 3.3, occurred at 2041 and 2050 on the 26th. No surface activity was observed.

Information Contacts: JMA.


April 1992 (BGVN 17:04) Citation IconCite this Report

Two seismic swarms; no surface changes evident

A seismic swarm occurred 21-25 April, centered a few kilometers NW of the island. Some of the shocks were felt by island residents; the largest, M 3.6, occurred on 23 April. Another swarm was recorded on 8 May, centered E of the island (maximum M 3.9). No surface anomalies were observed.

Information Contacts: JMA.


May 1992 (BGVN 17:05) Citation IconCite this Report

Continued seismic swarms

Abnormal seismicity continued around the volcano in May, when 2 earthquake swarms were recorded. On 8 May a swarm occurred 2-3 km E of the island, with M <3.9. The second, on 14-16 May, occurred 3-4 km NW, with the largest event (M 4.9) recorded at 0731 on 15 May. No surface anomalies were observed.

Information Contacts: JMA.


June 1992 (BGVN 17:06) Citation IconCite this Report

Earthquake and aftershocks

A M 5.2 earthquake, centered in the sea 8 km SW of the volcano at 9 km depth, occurred on 15 June at 1046. Island residents felt the shock at intensity 5 on the JMA scale of 0-7. Data from 30 stations of the Worldwide Standardized Seismic Network yielded magnitudes of 4.9 (mb) and 4.7 (Ms). One person was slightly injured by a rockfall, and wallrock collapse at 10 sites closed 5 roads to traffic. Aftershocks continued until 17 June off the island's SW coast. The event was the second largest since . . . April 1991 (figure 1). No surface anomalies were observed on the island or on the sea-surface nearby.

Information Contacts: JMA; NEIC.


August 1992 (BGVN 17:08) Citation IconCite this Report

Weak seismic swarm; surface activity unchanged

A weak earthquake swarm was detected 5 km NE of the volcano island on 18 August. Maximum magnitude was 3.0. No surface activity was evident on the island or in the sea.

Information Contacts: JMA.


September 1992 (BGVN 17:09) Citation IconCite this Report

Weak earthquake swarm

A weak earthquake swarm occurred 5 km W of the island on 1 September. Maximum magnitude was 2.1. No surface activity was evident on the island or in the sea.

Information Contacts: JMA.


October 1992 (BGVN 17:10) Citation IconCite this Report

Earthquake swarm but no surface changes evident

A swarm of earthquakes occurred midway between [Nii-jima and Kozu-shima] islands 17-20 October. The largest earthquake was M 5.1, at 2237 on 17 October. No ocean-surface anomalies were observed.

Information Contacts: JMA.


March 1993 (BGVN 18:03) Citation IconCite this Report

Earthquake swarm on 25 March; no surface anomalies

. . . On 25 March, a swarm occurred at Kozu-shima island, ~20 km SW of Nii-jima. The largest event was M 3.9. No surface anomalies, onshore or offshore, were observed . . . .

Information Contacts: JMA.


August 1993 (BGVN 18:08) Citation IconCite this Report

Earthquake swarms

An earthquake swarm near and below Kozu-shima island occurred on 9-10 August, with 12 shocks felt on the island, the largest M 3.3. Another earthquake near the island, M 3.7, occurred in the early morning on 22 August.

Information Contacts: JMA.


September 1995 (BGVN 20:09) Citation IconCite this Report

Strong earthquake swarm in early October

At 2143 on 6 October, a M 5.6 earthquake occurred near Kozu-shima (figure 2). The earthquake, which had an intensity at Kozu-shima of V on JMA's scale, caused a few landslides there. A M 4.8 earthquake 14 minutes earlier had an intensity of IV. During the next several days, an earthquake swarm continued offshore to the SW of Kozu-shima (figure 2, bottom). The swarm's maximum depth shifted downward with time, reaching 20-25 km. None of this seismicity was thought to have been induced by volcanism.

Figure (see Caption) Figure 2. Kozu-shima epicenter map (top) and plot of focal depths versus time for September through 16 October 1995 (bottom). Courtesy of JMA.

Though obscured by epicenters on figure 2, Kozu-shima island has dimensions of 4 x 6 km and lies 20 km SSW of Nii-jima island and adjacent to the Izu Peninsula. Kozu-shima contains abundant rhyolitic surge deposits and lava domes. Its last eruption was in 838-840 AD. Seismicity near the volcano, and sometimes in vicinity of Nii-jima, has been episodically high in recent years.

Information Contacts: Volcanological Division, Seismological and Volcanological Department, Japan Meteorological Agency (JMA), 1-3-4 Ote-machi, Chiyoda-ku, Tokyo 100 Japan.


October 1995 (BGVN 20:10) Citation IconCite this Report

Earthquake swarm ends in mid-October

As reported in BGVN 20:09, on 6 October a M 5.6 earthquake occurred adjacent to Kozu-shima and a seismic swarm followed for the next few days. After that, seismic events continued but decreased toward the end of October; in total, during October there were 246 felt earthquakes.

Information Contacts: Volcanological Division, Seismological and Volcanological Department, Japan Meteorological Agency (JMA), 1-3-4 Ote-machi, Chiyoda-ku, Tokyo 100 Japan.

This compilation of synonyms and subsidiary features may not be comprehensive. Features are organized into four major categories: Cones, Craters, Domes, and Thermal Features. Synonyms of features appear indented below the primary name. In some cases additional feature type, elevation, or location details are provided.

Eruptive History

There is data available for 4 confirmed Holocene eruptive periods.

0838 Aug 2 (?) Confirmed Eruption Max VEI: 4

Episode 1 | Eruption Episode Tenjo-san
0838 Aug 2 (?) - Unknown Evidence from Observations: Reported

List of 8 Events for Episode 1 at Tenjo-san

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Explosion violent, strong, or large
   - - - -    - - - - Pyroclastic flow
   - - - -    - - - - Lava flow
   - - - -    - - - - Lava flow Entered water.
   - - - -    - - - - Lava dome
   - - - -    - - - - Cinder Cone
   - - - -    - - - - Ash
0838 Aug 2
(?)
   - - - - VEI (Explosivity Index)

[ 0832 ] Uncertain Eruption

Episode 1 | Eruption Episode
0832 - Unknown Evidence from Unknown

List of 2 Events for Episode 1

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Lava flow Uncertain
   - - - -    - - - - Lava flow Entered water. Uncertain

0100 BCE ± 950 years Confirmed Eruption  

Episode 1 | Eruption Episode NW tip of island (Kobe-yama)
0100 BCE ± 950 years - Unknown Evidence from Chem/Bio: Hydration Rind

List of 2 Events for Episode 1 at NW tip of island (Kobe-yama)

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Lava flow
   - - - -    - - - - Lava dome

0750 BCE ± 700 years Confirmed Eruption  

Episode 1 | Eruption Episode N tip of island (Anano-yama, Hanatabe)
0750 BCE ± 700 years - Unknown Evidence from Chem/Bio: Hydration Rind

List of 2 Events for Episode 1 at N tip of island (Anano-yama, Hanatabe)

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Lava flow
   - - - -    - - - - Lava dome

8050 BCE (?) Confirmed Eruption  

Episode 1 | Eruption Episode Jogo-yama
8050 BCE (?) - Unknown Evidence from Correlation: Tephrochronology

List of 1 Events for Episode 1 at Jogo-yama

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Lava dome
Deformation History

There is data available for 1 deformation periods. Expand each entry for additional details.


Deformation during 2000 Jun 26 - 2000 Aug 18 [Uplift; Observed by GPS]

Start Date: 2000 Jun 26 Stop Date: 2000 Aug 18 Direction: Uplift Method: GPS
Magnitude: Unknown Spatial Extent: Unknown Latitude: Unknown Longitude: Unknown

Remarks: The 2000 dyking event is accompanied by seismicity and deformation. The intrusion was located between Miyakejima and Kozushima volcanoes.


Reference List: Yamaoka et al. 2005; Ueda et al. 2005.

Full References:

Ueda, H., E. Fujita, M. Ukawa, E. Yamamoto, M. Irwan, and F. Kimata, 2005. Magma intrusion and discharge process at the initial stage of the 2000 activity of Miyakejima, central Japan, inferred from tilt and GPS data. Geophysical Journal International, 161: 891-906. https://doi.org/10.1111/j.1365-246X.2005.02602.x

Yamaoka, K., M. Kawamura, F. Kimata, N. Fujii, and T. Kudo,, 2005. Dike intrusion associated with the 2000 eruption of Miyakejima Volcano, Japan. Bull Volcanol, 67: 231-242.

Emission History

There is no Emissions History data available for Kozushima.

GVP Map Holdings

Maps are not currently available due to technical issues.

The maps shown below have been scanned from the GVP map archives and include the volcano on this page. Clicking on the small images will load the full 300 dpi map. Very small-scale maps (such as world maps) are not included.

Smithsonian Sample Collections Database

There are no samples for Kozushima in the Smithsonian's NMNH Department of Mineral Sciences Rock and Ore collection.

External Sites