Ontakesan

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  • Volcanic Region
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  • Last Known Eruption
  • 35.893°N
  • 137.48°E

  • 3067 m
    10060 ft

  • 283040
  • Latitude
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  • Summit
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Most Recent Bulletin Report: November 2003 (BGVN 28:11)


Persistent long-term seismicity and occasional small white plumes

Seismic activity at On-take has been ongoing in recent years. Data provided by the Japan Meteorological Agency indicates that from January 2000 through April 2003 an average of 140 volcanic earthquakes per month were recorded by the local seismic station. The number usually ranged between 90 and 200 each month. Activity was higher in July 2001 (300 total events, with 65 on the 1st) and December 2002 (206 total events, with 63 on the 4th). No volcanic tremor was registered. White plumes rising no higher than 300 m were observed once in June 2000 and March 2001, and more frequently during November 2001-January 2002. Small white plumes were seen once per month in September-November 2002 and January-March 2003.

Information Contacts: Volcanological Division, Japan Meteorological Agency (JMA), 1-3-4 Ote-machi, Chiyoda-ku, Tokyo 100, Japan (URL: http://www.kishou.go.jp/).

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

Index of Bulletin Reports


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.

10/1979 (SEAN 04:10) First eruption in historical time

11/1979 (SEAN 04:11) More information on 28 October eruption

12/1979 (SEAN 04:12) Vapor emission declines; local earthquakes continue

01/1980 (SEAN 05:01) Vapor emission continues; acid water kills fish

04/1980 (SEAN 05:04) Emission of vapor and a little ash continues

05/1980 (SEAN 05:05) Emission of vapor and a little ash continues

06/1980 (SEAN 05:06) Steaming continues

04/1991 (BGVN 16:04) Earthquake swarms and tremor; no change in steam emission

05/1991 (BGVN 16:05) Earthquake swarms and tremor; renewed steam emission from 1979 vent

06/1991 (BGVN 16:06) Seismicity declines slightly; steam plumes

07/1991 (BGVN 16:07) Decreasing seismicity

11/1992 (BGVN 17:11) Earthquake swarm but no change in gas emission

08/1995 (BGVN 20:08) Small tremors in late August

07/1996 (BGVN 21:07) Seismic activity increases

11/2003 (BGVN 28:11) Persistent long-term seismicity and occasional small white plumes




Bulletin Reports

All information contained in these reports is preliminary and subject to change.


10/1979 (SEAN 04:10) First eruption in historical time

[JMA and Tokiko Tiba have made substantial revisions to this report.] On-take's first eruption in historic time began early on [28] October. Vapor emission apparently started at about 0500, then activity strengthened at about 0800 to emission of an [ash] column . . . [Activity increased further from around 1100.] A tephra column that included ash and lapilli . . . was rising 1,500 m, and ash was falling on the E flank. Tephra clouds were ejected [continuously] during the afternoon. [Only white vapor was emitted the next day.]

Tephra was ejected from several craters that [formed in a fissure about 300 m S of the summit (figure 1). There had been no fumaroles in the area]. . . .

Figure 1. Map of On-Take, courtesy of JMA. The 500-m-long zone of 28 October 1979 vents is shown by a heavy NW-SE line immediately S of the summit. The four large craters trending NNE from the summit were formed during an eruption 14C dated at 23,000 BP. The short north-northeasterly line 1 km N of the summit represents a succession of small prehistoric explosion craters.

The Kyodo radio network reported that officials were assessing damage caused by the eruption; damage was particularly heavy at Kaida, about [12 km NE of the summit (Kenga-mine)]. Some livestock had to be evacuated because of ashfall on pastureland.

An earthquake swarm, including a magnitude [5.3 shallow] event, was recorded in the On-take area in October 1978. . . .

Information Contacts: T. Tiba, National Science Museum, Tokyo; Kyodo Radio, Tokyo; USGS/NEIS, Denver CO.

11/1979 (SEAN 04:11) More information on 28 October eruption

On-take's first eruption in historic time began suddenly before dawn on 28 October. No initial explosion was heard and no shock wave was recorded by JMA seismic stations, [but long-duration tremor was recorded from 0520 that may have been eruption tremor]. Ash emission continued through the day, intermittently during the morning but continuously during the afternoon, with strongest activity at about 1400. A dark ash cloud rose about 1 km (figure 2). About 1.5 m of ash fell near the summit and a few tens of centimeters fell on the flank. [A few millimeters] were deposited on [the villages of] Kaida-mura (12 km NE) and Mitake-mura (14 km SE), [the nearest inhabited areas] and slight ashfall covered a wide area as far as 150 km NE of the volcano (figure 3). No ejections of incandescent blocks were seen, but aerial observers reported that blocks were scattered around the vents (see below). Activity declined to white vapor emission before dawn on 29 October, although a slight ashfall occurred at a nearby village that morning. Steaming continued at varying intensity through mid-November.

Figure 2. Eruption or vapor cloud height above the summit 28-October-16 November, courtesy of JMA.
Figure 3. Sketch map of S Honshu and Shikoku Islands, Japan. Area of ashfall from On-take is shaded. Courtesy of JMA.

During the eruption, numerous vents were active in a 500 m-long NW-SE-trending zone near the summit (figures 1 and 4). Along some portions of the zone, curtains of steam were visible from the air on 28 October. Kazuaki Nakamura reported that 10 small craters were seen during an aerial inspection on 3 November; four craters were emitting vapor. Takeshi Kobayashi, who has studied the volcano for 20 years, reported that no fumaroles existed prior to the eruption in the new vent zone.

Figure 4. Zone of new vents on On-Take, sketched from the air on 3 November 1979 by Kazuaki Nakamura. Numerous vents that had existed along the fissure on 28 October were no longer visible at the time of this flight. The 28 October ash cloud was ejected by Vent 1, the largest of the vents at 30 m diameter. The other vents emitted mostly white steam during the eruption.

No historical eruptions are known from On-take, one of Japan's larger stratovolcanoes. Kobayashi reports that the youngest 14C dates from On-take, 23,000 BP, are from scoria and lava flows composed of two-pyroxene andesite, ejected from at least five craters forming a NNE-SSW line on the N flank.

Further References. Aoki, H., 1980, A compilation of reports on the volcanic activity and hazards of the 1979 eruption of On-take volcano: Special publication by the research group for the 1979 On-take eruption, no. B-54-3, 168 p.

Aramaki, S., and Ossaka, J., 1983, Eruption of On-takesan, October 28, 1979, in XVIII IUGG General Assembly, Hamburg, Report on volcano activities and studies in Japan for the period from 1979 to 1982, p. 1-7.

Information Contacts: JMA, Tokyo; JMA also forwarded information from T. Kobayashi (Toyama Univ.); K. Nakamura, ERI, Univ. of Tokyo.

12/1979 (SEAN 04:12) Vapor emission declines; local earthquakes continue

In the 2 months since the 1-day eruption of 28 October, no ash ejection has been observed and vapor emission has declined. At the end of December, the vapor column was only 100 m high.

About 10 local seismic events per day have been recorded since instruments were installed [on 29 October]. Epicenters have been distributed along a sharply defined narrow linear zone extending about 2 km N-S on the SE flank. Earthquakes had been felt in the area for about 2 years, but the number of felt events declined to about 1 per week after the eruption.

Information Contacts: JMA, Tokyo.

01/1980 (SEAN 05:01) Vapor emission continues; acid water kills fish

Steam from the 28 October vents rose steadily to 100-200 m through January. No ashfalls have been observed in inhabited areas on the flanks since November, although snow in the summit area has been [slightly] darkened by ash and colored yellow by sulfur during this period. Muddy acidic water has been flowing from the 28 October vents since the eruption, killing fish in the Otaki River. The number of dead fish decreased in January. Local earthquake activity remained at November-December levels, about 10 recorded events per day.

Information Contacts: JMA, Tokyo.

04/1980 (SEAN 05:04) Emission of vapor and a little ash continues

Steady vapor emission, to 100-300 m heights, continued through March. Vapor emerged from four of the numerous (at least 10) vents formed during the eruption in a linear, 500-m-long, NW-SE-trending zone near the summit. Airphoto data show that three of the four active vents have increased in size since the eruption. Ash in the vapor columns has repeatedly caused slight darkening of the snow in the summit area.

Information Contacts: JMA, Tokyo.

05/1980 (SEAN 05:05) Emission of vapor and a little ash continues

Steady emission of a 100-300-m-high vapor column continued through early May. Ash had darkened snow in the summit area through March, but the snow melted in April. However, a pale dust cloud, presumably the source of the ash, continued to drift over the summit.

Information Contacts: JMA, Tokyo.

06/1980 (SEAN 05:06) Steaming continues

Quiet emission of white vapor continued through June. The vapor rose several hundred meters above four summit-area vents. JMA personnel removed temporary seismic equipment installed 29 October and discontinued the visual monitoring begun on that date.

Information Contacts: JMA, Tokyo.

04/1991 (BGVN 16:04) Earthquake swarms and tremor; no change in steam emission

Three earthquake swarms (20, 23, and 27 April) and four tremor episodes (27-28 April and 2 May) were recorded during late April-early May. The strongest swarm, on 20 April, lasted a few hours and included a M 1.6 event. None of the shocks were felt, and it was not possible to locate them accurately, but they were believed to be in the summit area. The 27 April tremor episode was the largest (table 1), and accompanying seismicity was the strongest registered (figure 5), since installation of the current seismometer, in July 1988.

Table 1. Tremor episodes recorded at On-take, 15 July 1988-11 May 1991.

    Date           Time   Amplitude (N)   Duration (min)

    02 Oct 1988    0132       0.1              1
    06 Oct 1988    1035       0.1              1
    12 Jan 1989    1725       0.6              1
    19 Aug 1989    1313       0.4              2
    11 Apr 1990    1808       0.2              2
    27 Apr 1991    0716       2.3              4
                   1201       0.1              2
    28 Apr 1991    1309       1.4              3
    02 May 1991    0938       0.3              3
Figure 5. Daily number of recorded earthquakes at On-take, 15 July 1988-5 May 1991. Courtesy of JMA.

White steam emissions, unchanged from previous months (figure 6), rose 200 m from summit vents formed during a small phreatic eruption in October 1979. That eruption emitted ash for 1 day; steam emission declined, but has remained steady since then.

Figure 6. Plume heights at On-take, 20 July 1988-13 May 1991. Courtesy of JMA.

A M 6.8 earthquake, 12 km SE of the summit on 14 September 1984, triggered a landslide on the S slope of the volcano that killed 29 people. Aftershocks were distributed on the volcano's S flank in an elliptical zone that may mark a 20-km-long WSW-ENE fault (figure 7). Steam emission and surface activity were unchanged by the 1984 earthquake.

Figure 7. Epicenter map of 138 earthquakes at On-take, January 1990-May 1991. Locations of the three swarms are not shown, but are considered to be in the summit area (triangle). The largest shock, M 1.8, was centered just W of the summit. The group of events in an E-W line 15 km S of the summit are aftershocks from a M 6.8 earthquake in 1984. Courtesy of JMA.

Information Contacts: JMA.

05/1991 (BGVN 16:05) Earthquake swarms and tremor; renewed steam emission from 1979 vent

Many earthquakes and tremor episodes have been detected by a seismometer near the volcano since April, bringing seismicity to its highest levels since the start of regular seismic monitoring in 1988. Earthquake swarms were recorded on 20, 23, and 27 April, and 12 and 13 May, with tremor on 27 and 28 April, and 2 and 12-16 May (figure 8). In mid-May, steam began to emerge from a vent formed in the last eruption (in 1979) that had remained quiet since soon after the eruption ended. Similar seismicity continued in June, and as of the 19th, 170 earthquakes and eight tremor episodes had been recorded.

Figure 8. Daily number of earthquakes (top) and tremor episodes (bottom) at On-take, January-May, 1991.

Information Contacts: JMA.

06/1991 (BGVN 16:06) Seismicity declines slightly; steam plumes

Seismicity has remained at high levels since April, with nine tremor episodes and 234 small earthquakes recorded in June (figure 9), down from 28 and 313, respectively, in May. Similar seismicity +continued as of 18 July. White steam plumes . . . rose to 200 m height.

Figure 9. Daily number of earthquakes from the start of monitoring in July 1989 through June 1991.

Information Contacts: JMA.

07/1991 (BGVN 16:07) Decreasing seismicity

Seismicity decreased in July, with 94 earthquakes and two tremor episodes recorded . . . (figure 10). Summit vents continued emitting white steam plumes but these rose weakly to ~ 100 m . . . .

Figure 10. Daily number of earthquakes January-15 August 1991.

Information Contacts: JMA.

11/1992 (BGVN 17:11) Earthquake swarm but no change in gas emission

A swarm of 40 small, shallow earthquakes, centered beneath the summit, were recorded between 1600 and 2000 on 12 November by a seismometer 2 km SE of the summit (figure 11). No change was recorded in the emission of steam, which has steadily risen to several tens of meters, and no volcanic tremor was recorded. This was the first increase in summit seismic activity since May 1991 when seismicity was accompanied by increased steaming and perhaps by minor ash ejection (Kazan, 1991).

Figure 11. Daily number of recorded earthquakes January 1990-December 1992.

Reference. Volcanic Activity in Japan during April-June 1991, 1991: Kazan, v. 36, no. 3, p. 385.

Information Contacts: JMA.

08/1995 (BGVN 20:08) Small tremors in late August

Small volcanic tremors were recorded in late August from a station 1.5 km SE of the summit.

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

07/1996 (BGVN 21:07) Seismic activity increases

High seismicity was recorded on 6 July with a total of 29 earthquakes.

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

11/2003 (BGVN 28:11) Persistent long-term seismicity and occasional small white plumes

Seismic activity at On-take has been ongoing in recent years. Data provided by the Japan Meteorological Agency indicates that from January 2000 through April 2003 an average of 140 volcanic earthquakes per month were recorded by the local seismic station. The number usually ranged between 90 and 200 each month. Activity was higher in July 2001 (300 total events, with 65 on the 1st) and December 2002 (206 total events, with 63 on the 4th). No volcanic tremor was registered. White plumes rising no higher than 300 m were observed once in June 2000 and March 2001, and more frequently during November 2001-January 2002. Small white plumes were seen once per month in September-November 2002 and January-March 2003.

Information Contacts: Volcanological Division, Japan Meteorological Agency (JMA), 1-3-4 Ote-machi, Chiyoda-ku, Tokyo 100, Japan (URL: http://www.kishou.go.jp/).

The massive Ontakesan stratovolcano, the second highest volcano in Japan, lies at the southern end of the Northern Japan Alps. It is constructed within a largely buried 4 x 5 km caldera and occupies the southern end of the Norikura volcanic zone, which extends northward to Yakedake volcano. The older volcanic complex consisted of at least four major stratovolcanoes constructed from about 680,000 to about 420,000 years ago, after which Ontakesan was inactive for more than 300,000 years. The broad, elongated summit of the younger edifice is cut by a series of small explosion craters along a NNE-trending line. Several phreatic eruptions post-date the roughly 7300-year-old Akahoya tephra from Kikai caldera. The first historical eruption took place in 1979. A non-eruptive landslide in 1984 produced a debris avalanche and lahar that swept down valleys south and east of the volcano. Ascending this volcano is one of the major objects of religious pilgrimage in central Japan.

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

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
2014 Sep 27 Unknown Confirmed 3 Historical Observations Summit crater
2007 Mar 24 ± 7 days Unknown Confirmed 0 Historical Observations 1979 Crater #7
1991 May 13 1991 May 16 Confirmed 0 Historical Observations 1979 Crater #7
1979 Oct 28 1980 Apr 25 Confirmed 2 Historical Observations 200 m SW of Kengamine
[ 0774 ] [ Unknown ] Uncertain    

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.


Synonyms

Kiso-ontake | On-take

Cones

Feature Name Feature Type Elevation Latitude Longitude
Komikasa-yama Cone 2045 m
Mikasa-yama Stratovolcano 2256 m
Tobu volcano group Stratovolcano
Tsuchiurazawa Stratovolcano
Uetawara-yama Stratovolcano

Craters

Feature Name Feature Type Elevation Latitude Longitude
Gono-ike Crater
Ichino-ike
    Itino-ike
Crater
Jigoku
    Zigoku
Crater
Marishiten Crater
Nino-ike Crater
Sanno-ike Crater
Shino-ike
    Sino-ike
Crater
The summit of On-take volcano provides a grand perspective of the Northern Japan Alps on the horizon. Norikura volcano, another massive Holocene stratovolcano, forms the broad massif in the middle distance. On-take is constructed within a largely buried 4 x 5 km caldera. Ichino-ike ("First Pond"), in the foreground, is one of a series of small explosion craters that cut the broad summit along a NNE-trending line. On-take's first historical eruption in 1979 followed a lengthy period of quiescence.

Photo by Lee Siebert, 1988 (Smithsonian Institution).
The most prominent feature on the upper SE flank of On-take volcano is not a crater, but the headwall scarp of a volcanic landslide. The landslide occurred suddenly on September 14, 1984, in the absence of any eruptive activity. The resulting debris avalanche swept 13 km down the Nigori and O-taki river valleys.

Photo by Lee Siebert, 1988 (Smithsonian Institution).
Vigorous steam plumes rise from vents along a fissure 300 m south of the summit on October 29, 1979, the day after the start of the first historical eruption from On-take volcano. During the first day of the eruption, ash and lapilli were ejected in an eruption column that reached 1.5 km above the vent. Strong vapor emission with periodic minor ashfall that dusted the summit region continued for several months. No fumaroles existed at this location prior to the eruption.

Photo by T. Kobayashi, 1979 (courtesy Tokiko Tiba, National Science Museum).
Vigorous steam plumes rise from craters near the summit of On-take volcano on November 9, 1979. The first historical eruption from On-take, in central Honshu, Japan, began on October 28 and produced ashfall to the NE from a 1.5-km-high eruption plume. Intense vapor emission (with minor ash that dusted the summit region) continued for several months.

Photo by T. Kobayashi, 1979 (courtesy Tokiko Tiba, National Science Museum).
Massive On-take volcano is seen here from the NE with Kengamine, the summit peak, at the left-center. On-take is the second highest volcano in Japan and lies at the southern end of the Northern Japan Alps. The broad, elongated summit is cut by a series of small explosion craters along a NNE-trending line. On-take's first historical eruption in 1979 followed a lengthy period of quiescence. Ascent of the 3063-m-high On-take is one of the major objects of religious pilgrimage in central Japan.

Copyrighted photo by Shun Nakano (Japanese Quaternary Volcanoes database, RIODB, http://riodb02.ibase.aist.go.jp/strata/VOL_JP/EN/index.htm and Geol Surv Japan, AIST, http://www.gsj.jp/).

The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography. Discussion of another volcano or eruption (sometimes far from the one that is the subject of the manuscript) may produce a citation that is not at all apparent from the title.

Japan Meteorological Agency, 1996. National Catalogue of the Active Volcanoes in Japan (second edition). Tokyo: Japan Meteorological Agency, 502 p (in Japanese).

Japan Meteorological Agency, 2013. National Catalogue of the Active Volcanoes in Japan (fourth edition, English version). Japan Meteorological Agency.

Kudo T, Hoshizumi H, 2006-. Catalog of eruptive events within the last 10,000 years in Japan, database of Japanese active volcanoes. Geol Surv Japan, AIST, http://riodb02.ibase.aist.go.jp/db099/eruption/index.html.

Kuno H, 1962. Japan, Taiwan and Marianas. Catalog of Active Volcanoes of the World and Solfatara Fields, Rome: IAVCEI, 11: 1-332.

Matsumoto A, Kobayashi T, 1999. K-Ar ages of the Older Ontake volcanic products, Ontake volcano, Central Japan: reappraisal of the volcanic history based on radiometric data. Bull Volc Soc Japan (Kazan), 44: 1-12 (in Japanese with English abs).

Nakano S, Yamamoto T, Iwaya T, Itoh J, Takada A, 2001-. Quaternary Volcanoes of Japan. Geol Surv Japan, AIST, http://www.aist.go.jp/RIODB/strata/VOL_JP/.

Newhall C G, Dzurisin D, 1988. Historical unrest at large calderas of the world. U S Geol Surv Bull, 1855: 1108 p, 2 vol.

Volcano Types

Complex

Tectonic Setting

Subduction zone
Continental crust (> 25 km)

Rock Types

Major
Andesite / Basaltic Andesite
Basalt / Picro-Basalt
Dacite
Rhyolite

Population

Within 5 km
Within 10 km
Within 30 km
Within 100 km
176
2,098
86,634
8,307,889

Affiliated Databases

Large Eruptions of Ontakesan Information about large Quaternary eruptions (VEI >= 4) is cataloged in the Large Magnitude Explosive Volcanic Eruptions (LaMEVE) database of the Volcano Global Risk Identification and Analysis Project (VOGRIPA).
WOVOdat WOVOdat is a database of volcanic unrest; instrumentally and visually recorded changes in seismicity, ground deformation, gas emission, and other parameters from their normal baselines. It is sponsored by the World Organization of Volcano Observatories (WOVO) and presently hosted at the Earth Observatory of Singapore.
EarthChem EarthChem develops and maintains databases, software, and services that support the preservation, discovery, access and analysis of geochemical data, and facilitate their integration with the broad array of other available earth science parameters. EarthChem is operated by a joint team of disciplinary scientists, data scientists, data managers and information technology developers who are part of the NSF-funded data facility Integrated Earth Data Applications (IEDA). IEDA is a collaborative effort of EarthChem and the Marine Geoscience Data System (MGDS).
Smithsonian Collections Search the Smithsonian's NMNH Department of Mineral Sciences collections database. Go to the "Search Rocks and Ores" tab and use the Volcano Name drop-down to find samples.