Adatarayama

Photo of this volcano
  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 37.647°N
  • 140.281°E

  • 1728 m
    5668 ft

  • 283170
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number

Most Recent Bulletin Report: September 1997 (BGVN 22:09) Citation IconCite this Report


Four hikers killed in a gas-filled depression

Four hikers died from inhalation of volcanic gases after being exposed to fumes on the floor of Numano-taira (also called Numano-daira) crater on 15 September. The hikers were part of a group of 14 Tokyo barbers who became disoriented in foggy conditions and departed from a trail. After three hikers fell at the head of a small valley in the S rim of the crater, another member of the party attempted a rescue but also fell to the floor of the crater, where deadly gases had accumulated due to light northerly winds. Other hikers in the area noticed a strong sulfuric odor, warned others of the danger, and climbed to higher ground. Signs warning of the volcanic gas hazard were posted at the trail head.

According to scientists at the Kusatsu-Shirane Volcano Observatory, fumarolic gas from the SW part of the crater is composed of 0.5% SO2, 60-65% H2S and 33-37% CO2. Gas collected in July from a mud pond on the crater floor contained 41% H2S and 56% CO2. The most likely reason for the fatalities was the presence of the H2S and the calm wind conditions that allowed gases to accumulate in the lowest part of the crater.

The Japan Meteorological Agency (JMA) released a report on recent activity at the volcano including a volcanic gas advisory on 15 September. The report details 5 volcanic earthquakes that occurred in August and increased mud spouting and fumarolic activity. Other activity reported at the crater included mud effusion at three pits on the crater floor in July and August 1996 as well as a very small-scale phreatic explosion on 1 September 1996 (BGVN 21:08).

Information Contacts: Jun-ichi Hirabayashi, Kusatsu-Shirane Volcano Observatory, Tokyo Institute of Technology, Kusatsu, Agatsuma-gun, Gunma 377-17, Japan (Email: jhirabay@ksvo.titech.ac.jp); Noritake Nishide, Sendai District Meteorological Observatory, Japan Meteorological Agency (JMA), 1-3- 15 Gorin, Miyagino-ku, Sendai 983, Japan (Email: nnishide@redc-sn.eqvol.kishou.go.jp); Yoshihisa Kawanabe, Volcanology Section, Environmental Geology Department, Geological Survey of Japan, 1-1-3, Higashi, Tsukuba, Ibaraki, 305 Japan (Email: yagi@gsj.go.jp); Tatsuro Chiba, Dept of Disaster Prevention, Asia Air Survey Co., 4-2-18 Shinjuku, Shinjuku-ku, Tokyo 160, Japan (Email: tatsuro-chi@aix.or.jp, URL: http://pweb.aix. or.jp/~tatsuro-chi/hachi/hachi-e.html or http://www.geo.chs.nihon-u.ac. jp/tchiba/ada/ada-e.html); Volcano Research Center, University of Tokyo, Yayoi, Bunkyo-ku, Tokyo 113, Japan (Email: nakada@eri.u-tokyo.ac.jp, URL: http://hakone.eri.u-tokyo.ac.jp/erup/adatara.html).

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

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.

10/1995 (BGVN 20:10) First tremor since 1965

04/1996 (BGVN 21:04) Volcanic tremor detected on four days in April

08/1996 (BGVN 21:08) A small aseismic, phreatic eruption on 1 September

09/1997 (BGVN 22:09) Four hikers killed in a gas-filled depression




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


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


First tremor since 1965

During 27 October, volcanic tremor of about 3-minutes duration was recorded at a site 4.8 km NE of Adatara's summit (station A). This was the first case of tremor since the local observatory began observations in 1965.

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


April 1996 (BGVN 21:04) Citation IconCite this Report


Volcanic tremor detected on four days in April

On 12, 15, 25, and 26 April, small-amplitude volcanic tremors were detected. Volcanic tremor was previously recorded on 27 October 1995 (BGVN 20:10), the first such occurrence since observations began in 1965.

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


August 1996 (BGVN 21:08) Citation IconCite this Report


A small aseismic, phreatic eruption on 1 September

A small-scale phreatic eruption suddenly took place on 1 September. On 4 September a survey team from the Japan Meteorological Agency (JMA) verified that mud was sprayed ~100 m from small pits at the summit area (Numanotaira). Mud crusts and mud flows were found around three pits, and a strong odor of sulfurous gas was noted. Some mountaineers witnessed and photographed this eruption. Although both Tohoku University and JMA monitor seismicity of the volcano, no seismic activity was recorded just prior to or during the eruption. After the eruption, there was also no evidence implying an increase in seismicity. This has been the first observation of eruptive phenomena since monitoring began in 1965. Volcanic tremor was last reported in April (BGVN 21:04). The JMA seismic net also recorded volcanic tremor once in June.

A survey by Tatsuro Chiba of Asia Air Survey Co. Ltd. indicated that mud effusion on the Numanotaira crater floor also occurred in July and August of this year. The Asahi TV Company took pictures of mud bubbling in one of the pits during mid-August. According to Tatsuro Chiba, two of three pits in the crater already had existed before 1 September and the third pit might have been formed during the 1 September eruption.

Information Contacts: Volcanological Division, Japan Meteorological Agency (JMA), 1-3-4 Ote-machi, Chiyoda-ku, Tokyo 100, Japan; Volcano Research Center, Earthquake Research Institute (ERI), University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113, Japan (URL: http://hakone.eri.u-tokyo.ac.jp/ vrc/VRC.html).


September 1997 (BGVN 22:09) Citation IconCite this Report


Four hikers killed in a gas-filled depression

Four hikers died from inhalation of volcanic gases after being exposed to fumes on the floor of Numano-taira (also called Numano-daira) crater on 15 September. The hikers were part of a group of 14 Tokyo barbers who became disoriented in foggy conditions and departed from a trail. After three hikers fell at the head of a small valley in the S rim of the crater, another member of the party attempted a rescue but also fell to the floor of the crater, where deadly gases had accumulated due to light northerly winds. Other hikers in the area noticed a strong sulfuric odor, warned others of the danger, and climbed to higher ground. Signs warning of the volcanic gas hazard were posted at the trail head.

According to scientists at the Kusatsu-Shirane Volcano Observatory, fumarolic gas from the SW part of the crater is composed of 0.5% SO2, 60-65% H2S and 33-37% CO2. Gas collected in July from a mud pond on the crater floor contained 41% H2S and 56% CO2. The most likely reason for the fatalities was the presence of the H2S and the calm wind conditions that allowed gases to accumulate in the lowest part of the crater.

The Japan Meteorological Agency (JMA) released a report on recent activity at the volcano including a volcanic gas advisory on 15 September. The report details 5 volcanic earthquakes that occurred in August and increased mud spouting and fumarolic activity. Other activity reported at the crater included mud effusion at three pits on the crater floor in July and August 1996 as well as a very small-scale phreatic explosion on 1 September 1996 (BGVN 21:08).

Information Contacts: Jun-ichi Hirabayashi, Kusatsu-Shirane Volcano Observatory, Tokyo Institute of Technology, Kusatsu, Agatsuma-gun, Gunma 377-17, Japan (Email: jhirabay@ksvo.titech.ac.jp); Noritake Nishide, Sendai District Meteorological Observatory, Japan Meteorological Agency (JMA), 1-3- 15 Gorin, Miyagino-ku, Sendai 983, Japan (Email: nnishide@redc-sn.eqvol.kishou.go.jp); Yoshihisa Kawanabe, Volcanology Section, Environmental Geology Department, Geological Survey of Japan, 1-1-3, Higashi, Tsukuba, Ibaraki, 305 Japan (Email: yagi@gsj.go.jp); Tatsuro Chiba, Dept of Disaster Prevention, Asia Air Survey Co., 4-2-18 Shinjuku, Shinjuku-ku, Tokyo 160, Japan (Email: tatsuro-chi@aix.or.jp, URL: http://pweb.aix. or.jp/~tatsuro-chi/hachi/hachi-e.html or http://www.geo.chs.nihon-u.ac. jp/tchiba/ada/ada-e.html); Volcano Research Center, University of Tokyo, Yayoi, Bunkyo-ku, Tokyo 113, Japan (Email: nakada@eri.u-tokyo.ac.jp, URL: http://hakone.eri.u-tokyo.ac.jp/erup/adatara.html).

Eruptive History


Summary of Holocene eruption dates and Volcanic Explosivity Indices (VEI).


Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
1996 Sep 1 1996 Sep 1 Confirmed 1 Historical Observations Numanotaira
1900 Jul 17 1900 Jul 17 Confirmed 2 Historical Observations Numanotaira
1899 Aug 24 1899 Nov 12 Confirmed 2 Historical Observations Numanotaira
[ 1813 Jan 10 ] [ Unknown ] Uncertain 1   Numanotaira
0950 ± 50 years Unknown Confirmed   Tephrochronology Numanotaira, Ad-p4 tephra
0050 BCE ± 900 years Unknown Confirmed   Tephrochronology Numanotaira, Ad-p3 tephra
0590 BCE ± 200 years Unknown Confirmed 3 Radiocarbon (corrected) Numanotaira, Ad-NT6 tephra
1550 BCE ± 1100 years Unknown Confirmed   Tephrochronology Numanotaira, Ad-p1, p2 tephras
2600 BCE ± 50 years Unknown Confirmed 3 Radiocarbon (corrected) Numanotaira, Ad-NT5 tephra
4300 BCE ± 850 years Unknown Confirmed 3 Tephrochronology Numanotaira, Ad-NT4 tephra
6150 BCE ± 100 years Unknown Confirmed 3 Radiocarbon (corrected) Numanotaira, Ad-NT3 tephra
6650 BCE ± 100 years Unknown Confirmed 3 Radiocarbon (corrected) Numanotaira, Ad-NT2 tephra
8050 BCE (?) Unknown Confirmed 3 Tephrochronology Numanotaira, Ad-NT1 tephra

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.

Photo Gallery


The broad forested massif of Adatara volcano, seen here from the west, is composed of a group of stratovolcanoes capped by lava domes. The unvegetated area on the left summit ridge is a 1-km-wide circular crater that is breached by the Iwo-gawa (Sulfur River) on the west. The crater has been mined for sulfur. Seventy-two miners working in the summit crater were killed during an explosive eruption in 1900.

Photo by Lee Siebert, 1988 (Smithsonian Institution).
See title for photo information.

Smithsonian Sample Collections Database


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

Affiliated Sites