Global Volcanism Program | Zaozan [Zaosan]

Zaozan [Zaosan]

Google Earth Placemark with Features

Cite Volcano Profile

Japan
Northeast Japan Volcanic Arc
Composite | Complex
1940 CE

Country
Volcanic Region
Landform | Volc Type
Last Known Eruption

38.144°N
140.44°E
1,841 m
6,040 ft
283190

Latitude
Longitude
Summit
Elevation
Volcano
Number

Most Recent Weekly Report: 24 January-30 January 2018 Cite this Report

JMA reported that tremor was detected at Zaozan on 28 and 30 January, and minor inflation at the S part of the volcano was recorded. There were 12 volcanic earthquakes detected on 31 January. JMA raised the Alert level to 2 (on a 5-level scale), noting the increased potential for a small eruption.

Source: Japan Meteorological Agency (JMA)

Most Recent Bulletin Report: September 1992 (BGVN 17:09) Cite this Report

Earthquake and numerous aftershocks, but no surface changes evident

A seismic shock of M 4.7 occurred at 1758 on 1 September a few kilometers ESE of the summit. The shock was felt at JMA intensity IV near the volcano, and was weakly felt at Sendai (35 km E), Fukushima (45 km S), and Onahama (135 km E). Aftershocks were numerous, but declined toward mid-September. The high seismicity was the first at the volcano since July 1990, when there were many small earthquakes below the summit. Surveys of fumarolic areas on 5 September revealed no changes in temperature from the last survey in 1990.

Information Contacts: JMA.

Weekly Reports - Index

2018: January

24 January-30 January 2018 Cite this Report

Source: Japan Meteorological Agency (JMA)

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.

09/1992 (BGVN 17:09) Earthquake and numerous aftershocks, but no surface changes evident

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

September 1992 (BGVN 17:09) Cite this Report

Earthquake and numerous aftershocks, but no surface changes evident

Information Contacts: JMA.

Basic Data

Volcano Number

Last Known Eruption

Elevation

Latitude
Longitude

283190

1940 CE

1,841 m / 6,040 ft

38.144°N
140.44°E

Morphology

Volcano Landform
Composite

Volcano Types
Complex

Rock Types

Major
Andesite / Basaltic Andesite
Basalt / Picro-Basalt
Dacite

Tectonic Setting

Subduction zone
Continental crust (> 25 km)

Population

Within 5 km
Within 10 km
Within 30 km
Within 100 km

632
4,681
550,409
4,956,958

Geological Summary

The Zaozan (or Zaosan) volcano group consists of a complex cluster of stratovolcanoes in north-central Honshu about 40 km W of Sendai Bay. The Pleistocene Ryuzan volcano forms the western group (Nishi-Zao), and Byobu and Fubo volcanoes form the southern group (Minami-Zao). The complex was constructed over granitic basement rocks thus has a relatively small volume. The 7 km³ Zaozan volcano proper forms the central group (Chuo-Zao), a complex topped by several lava domes and the Goshikidake tuff cone, aligned NW-SE. Several episodes of edifice collapse produced debris avalanches during the Pleistocene. Goshikidake contains the active Okama crater, filled with a colorful, strongly acidic crater lake; it has been the source of most of the frequent eruptions recorded since the 8th century CE.

References

The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography.

Hasenaka T, Ui T, Nakamura Y, Hayashi S, 1992. Traverse of Quaternary volcanoes in Japan. 29th Internatl Geol Cong, Kyoto, Field Trip A06, 74 p.

IAVCEI, 1973-80. Post-Miocene Volcanoes of the World. IAVCEI Data Sheets, Rome: Internatl Assoc Volc Chemistry Earth's Interior.

Ichimura T, 1951. Geological investigations on the Zao volcanoes. 1. Goshikidake, a central cone of the Zao proper. Bull Earthq Res Inst, Univ Tokyo, 39: 327-339.

Ishikawa H, Ohba T, Fujimaki H, 2007. Sr isotope diversity of hot spring and volcanic lake waters from Zao volcano, Japan. Journal of Volcanology and Geothermal Research, 166: 7-16.

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

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

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, https://gbank.gsj.jp/volcano/index_e.htm.

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

Miura K, Ban M, Yagi H, 2008. The tephra layers distributed around the eastern foot of the Zao volcano--ages and volumes of the Za-To 1 to 4 tephras. Bull Volc Soc Japan (Kazan), 53: 151-157.

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/.

Eruptive History

There is data available for 43 confirmed Holocene eruptive periods.

1940 May 18 - 1940 May 18 Confirmed Eruption (Explosive / Effusive) VEI: 1

Episode 1 | Eruption (Explosive / Effusive)

Okama

1940 May 18 - 1940 May 18

Evidence from Observations: Reported

List of 5 Events for Episode 1 at Okama

Start Date	End Date	Event Type	Event Remarks
- - - -	- - - -	Phreatic activity	weak or small
- - - -	- - - -	Ash
- - - -	- - - -	Lapilli
- - - -	- - - -	Blocks
1940 May 18	- - - -	VEI (Explosivity Index)

[ 1939 Jul ] Uncertain Eruption

Episode 1 | Eruption (Explosive / Effusive)

Okama

1939 Jul - Unknown

Evidence from Unknown

List of 3 Events for Episode 1 at Okama

Start Date	End Date	Event Type	Event Remarks
- - - -	- - - -	Phreatic activity	Uncertain
- - - -	- - - -	Lahar or Mudflow
1939 Jul	- - - -	VEI (Explosivity Index)

[ 1927 ] Uncertain Eruption

Episode 1 | Eruption (Explosive / Effusive)

Okama

1927 - Unknown

Evidence from Unknown

List of 2 Events for Episode 1 at Okama

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Phreatic activity	Uncertain
	1927	- - - -	VEI (Explosivity Index)

[ 1906 ] Discredited Eruption

1905 Confirmed Eruption (Explosive / Effusive) VEI: 1 (?)

Episode 1 | Eruption (Explosive / Effusive)

Okama

1905 - Unknown

Evidence from Observations: Reported

List of 2 Events for Episode 1 at Okama

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Phreatic activity	Uncertain
	1905	- - - -	VEI (Explosivity Index)

[ 1897 Jan 14 - 1897 Jan 14 ] Uncertain Eruption

Episode 1 | Eruption (Explosive / Effusive)

Okama

1897 Jan 14 - 1897 Jan 14

Evidence from Unknown

List of 4 Events for Episode 1 at Okama

Start Date	End Date	Event Type	Event Remarks
- - - -	- - - -	Phreatic activity	Uncertain
- - - -	- - - -	Volcanic "smoke"
- - - -	- - - -	Audible Sounds
1897 Jan 14	- - - -	VEI (Explosivity Index)

[ 1896 Sep 1 (?) ] Uncertain Eruption

Episode 1 | Eruption (Explosive / Effusive)

Okama

1896 Sep 1 (?) - Unknown

Evidence from Unknown

List of 2 Events for Episode 1 at Okama

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Phreatic activity	Uncertain
	1896 Sep 1 (?)	- - - -	VEI (Explosivity Index)

1896 Mar 8 - 1896 Mar 8 Confirmed Eruption (Explosive / Effusive) VEI: 1

Episode 1 | Eruption (Explosive / Effusive)

Okama

1896 Mar 8 - 1896 Mar 8

Evidence from Observations: Reported

List of 3 Events for Episode 1 at Okama

Start Date	End Date	Event Type	Event Remarks
- - - -	- - - -	Phreatic activity
- - - -	- - - -	Ash	weak or small
1896 Mar 8	- - - -	VEI (Explosivity Index)

1895 Aug 22 - 1895 Sep 28 Confirmed Eruption (Explosive / Effusive) VEI: 2

Episode 1 | Eruption (Explosive / Effusive)

Okama

1895 Aug 22 - 1895 Sep 28

Evidence from Observations: Reported

List of 5 Events for Episode 1 at Okama

Start Date	End Date	Event Type
- - - -	- - - -	Phreatic activity
- - - -	- - - -	Ash
- - - -	- - - -	Lahar or Mudflow
- - - -	- - - -	Property Damage
1895 Aug 22	- - - -	VEI (Explosivity Index)

1895 Feb 15 - 1895 Mar 22 Confirmed Eruption (Explosive / Effusive) VEI: 1

Episode 1 | Eruption (Explosive / Effusive)

Okama

1895 Feb 15 - 1895 Mar 22

Evidence from Observations: Reported

List of 6 Events for Episode 1 at Okama

Start Date	End Date	Event Type	Event Remarks
- - - -	- - - -	Phreatic activity	Uncertain
- - - -	- - - -	Ash
- - - -	- - - -	Lapilli
- - - -	- - - -	Lahar or Mudflow
- - - -	- - - -	Fauna Kill	Aquatic.
1895 Feb 15	- - - -	VEI (Explosivity Index)

1894 Jul 3 - 1894 Jul 3 Confirmed Eruption (Explosive / Effusive) VEI: 2 (?)

Episode 1 | Eruption (Explosive / Effusive)

Okama

1894 Jul 3 - 1894 Jul 3

Evidence from Observations: Reported

List of 3 Events for Episode 1 at Okama

Start Date	End Date	Event Type	Event Remarks
- - - -	- - - -	Phreatic activity	Uncertain
- - - -	- - - -	Ash
1894 Jul 3	- - - -	VEI (Explosivity Index)

[ 1890 ] Uncertain Eruption

Episode 1 | Eruption (Explosive / Effusive)

Okama

1890 - Unknown

Evidence from Unknown

List of 2 Events for Episode 1 at Okama

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Phreatic activity	Uncertain
	1890	- - - -	VEI (Explosivity Index)

1873 Aug - 1873 Sep Confirmed Eruption (Explosive / Effusive) VEI: 1 (?)

Episode 1 | Eruption (Explosive / Effusive)

Okama

1873 Aug - 1873 Sep

Evidence from Observations: Reported

List of 2 Events for Episode 1 at Okama

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Phreatic activity	Uncertain
	1873 Aug	- - - -	VEI (Explosivity Index)

1867 Oct 21 Confirmed Eruption (Explosive / Effusive) VEI: 2

Episode 1 | Eruption (Explosive / Effusive)

Okama

1867 Oct 21 - Unknown

Evidence from Observations: Reported

List of 5 Events for Episode 1 at Okama

Start Date	End Date	Event Type	Event Remarks
- - - -	- - - -	Phreatic activity	Uncertain
- - - -	- - - -	Lahar or Mudflow
- - - -	- - - -	Property Damage	Uncertain
1867 Oct 21	- - - -	Fatalities
1867 Oct 21	- - - -	VEI (Explosivity Index)

1833 Confirmed Eruption (Explosive / Effusive) VEI: 2

Episode 1 | Eruption (Explosive / Effusive)

Okama

1833 - Unknown

Evidence from Observations: Reported

List of 3 Events for Episode 1 at Okama

Start Date	End Date	Event Type	Event Remarks
- - - -	- - - -	Phreatic activity	Uncertain
- - - -	- - - -	Ash
1833	- - - -	VEI (Explosivity Index)

1831 Nov 22 Confirmed Eruption (Explosive / Effusive) VEI: 2

Episode 1 | Eruption (Explosive / Effusive)

Okama

1831 Nov 22 - Unknown

Evidence from Observations: Reported

List of 3 Events for Episode 1 at Okama

Start Date	End Date	Event Type	Event Remarks
- - - -	- - - -	Phreatic activity	Uncertain
- - - -	- - - -	Lahar or Mudflow	Uncertain
1831 Nov 22	- - - -	VEI (Explosivity Index)

1830 Confirmed Eruption (Explosive / Effusive) VEI: 2

Episode 1 | Eruption (Explosive / Effusive)

Okama

1830 - Unknown

Evidence from Observations: Reported

List of 2 Events for Episode 1 at Okama

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Phreatic activity	Uncertain
	1830	- - - -	VEI (Explosivity Index)

1822 May 1 Confirmed Eruption (Explosive / Effusive)

Episode 1 | Eruption (Explosive / Effusive)

1822 May 1 - Unknown

Evidence from Observations: Reported

List of 1 Events for Episode 1

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Phreatic activity	Uncertain

1821 Jan 27 - 1821 May 1 Confirmed Eruption (Explosive / Effusive) VEI: 2

Episode 1 | Eruption (Explosive / Effusive)

Okama

1821 Jan 27 - 1821 May 1

Evidence from Observations: Reported

List of 6 Events for Episode 1 at Okama

Start Date	End Date	Event Type	Event Remarks
- - - -	- - - -	Explosion	Uncertain
- - - -	- - - -	Ash
- - - -	- - - -	Lapilli
- - - -	- - - -	Lahar or Mudflow
1821 Jan 27	- - - -	VEI (Explosivity Index)
1821 May 1	- - - -	VEI (Explosivity Index)

1809 Jun 12 - 1809 Dec 29 Confirmed Eruption (Explosive / Effusive) VEI: 2

Episode 1 | Eruption (Explosive / Effusive)

Okama

1809 Jun 12 - 1809 Dec 29

Evidence from Observations: Reported

List of 6 Events for Episode 1 at Okama

Start Date	End Date	Event Type	Event Remarks
- - - -	- - - -	Phreatic activity	Uncertain
- - - -	- - - -	Ash
- - - -	- - - -	Lahar or Mudflow
- - - -	- - - -	Fauna Kill	Aquatic.
- - - -	- - - -	Property Damage	Uncertain
1809 Jun 12	- - - -	VEI (Explosivity Index)

1806 Jul 12 Confirmed Eruption (Explosive / Effusive) VEI: 2

Episode 1 | Eruption (Explosive / Effusive)

Okama

1806 Jul 12 - Unknown

Evidence from Observations: Reported

List of 2 Events for Episode 1 at Okama

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Phreatic activity	Uncertain
	1806 Jul 12	- - - -	VEI (Explosivity Index)

1804 May (?) Confirmed Eruption (Explosive / Effusive) VEI: 2

Episode 1 | Eruption (Explosive / Effusive)

Okama

1804 May (?) - Unknown

Evidence from Observations: Reported

List of 2 Events for Episode 1 at Okama

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Phreatic activity	Uncertain
	1804 May (?)	- - - -	VEI (Explosivity Index)

1796 Mar 24 Confirmed Eruption (Explosive / Effusive) VEI: 2

Episode 1 | Eruption (Explosive / Effusive)

Okama

1796 Mar 24 - Unknown

Evidence from Observations: Reported

List of 2 Events for Episode 1 at Okama

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Phreatic activity	Uncertain
	1796 Mar 24	- - - -	VEI (Explosivity Index)

1794 Sep 22 - 1794 Dec (on or after) Confirmed Eruption (Explosive / Effusive) VEI: 2

Episode 1 | Eruption (Explosive / Effusive)

SE side of Okama

1794 Sep 22 - 1794 Dec (on or after)

Evidence from Observations: Reported

List of 4 Events for Episode 1 at SE side of Okama

Start Date	End Date	Event Type	Event Remarks
- - - -	- - - -	Phreatic activity	Uncertain
- - - -	- - - -	Ash
- - - -	- - - -	Property Damage
1794 Sep 22	- - - -	VEI (Explosivity Index)

1694 May 29 - 1694 Aug 30 (?) Confirmed Eruption (Explosive / Effusive) VEI: 2

Episode 1 | Eruption (Explosive / Effusive)

Okama

1694 May 29 - 1694 Aug 30 (?)

Evidence from Observations: Reported

List of 7 Events for Episode 1 at Okama

Start Date	End Date	Event Type	Event Remarks
- - - -	- - - -	Explosion	Uncertain
- - - -	- - - -	Phreatic activity
- - - -	- - - -	Earthquakes (undefined)
- - - -	- - - -	Lahar or Mudflow
- - - -	- - - -	Fauna Kill	Aquatic.
- - - -	- - - -	Property Damage
1694 May 29	- - - -	VEI (Explosivity Index)

1670 Apr 26 - 1670 Sep 26 Confirmed Eruption (Explosive / Effusive) VEI: 2

Episode 1 | Eruption (Explosive / Effusive)

Okama

1670 Apr 26 - 1670 Sep 26

Evidence from Observations: Reported

List of 5 Events for Episode 1 at Okama

Start Date	End Date	Event Type
- - - -	- - - -	Explosion
- - - -	- - - -	Phreatic activity
- - - -	- - - -	Ash
1670 Apr 26	- - - -	VEI (Explosivity Index)
1670 Aug 13	- - - -	VEI (Explosivity Index)

1669 Confirmed Eruption (Explosive / Effusive) VEI: 3

Episode 1 | Eruption (Explosive / Effusive)

Okama

1669 - Unknown

Evidence from Observations: Reported

List of 4 Events for Episode 1 at Okama

Start Date	End Date	Event Type
- - - -	- - - -	Explosion
- - - -	- - - -	Ash
- - - -	- - - -	Property Damage
1669	- - - -	VEI (Explosivity Index)

1668 Aug Confirmed Eruption (Explosive / Effusive) VEI: 2 (?)

Episode 1 | Eruption (Explosive / Effusive)

Okama

1668 Aug - Unknown

Evidence from Observations: Reported

List of 2 Events for Episode 1 at Okama

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Explosion	Uncertain
	1668 Aug	- - - -	VEI (Explosivity Index)

1641 Confirmed Eruption (Explosive / Effusive) VEI: 2 (?)

Episode 1 | Eruption (Explosive / Effusive)

Okama

1641 - Unknown

Evidence from Observations: Reported

List of 2 Events for Episode 1 at Okama

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Explosion	Uncertain
	1641	- - - -	VEI (Explosivity Index)

1630 Confirmed Eruption (Explosive / Effusive) VEI: 2 (?)

Episode 1 | Eruption (Explosive / Effusive)

Okama

1630 - Unknown

Evidence from Observations: Reported

List of 2 Events for Episode 1 at Okama

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Explosion	Uncertain
	1630	- - - -	VEI (Explosivity Index)

1623 May 15 (?) - 1624 Nov 15 (?) Confirmed Eruption (Explosive / Effusive) VEI: 3

Episode 1 | Eruption (Explosive / Effusive)

Okama

1623 May 15 (?) - 1624 Nov 15 (?)

Evidence from Observations: Reported

List of 6 Events for Episode 1 at Okama

Start Date	End Date	Event Type
- - - -	- - - -	Explosion
- - - -	- - - -	Ash
- - - -	- - - -	Blocks
- - - -	- - - -	Audible Sounds
1623 May 15 (?)	- - - -	VEI (Explosivity Index)
1624 Feb 6	- - - -	VEI (Explosivity Index)

1622 Confirmed Eruption (Explosive / Effusive) VEI: 2 (?)

Episode 1 | Eruption (Explosive / Effusive)

Okama

1622 - Unknown

Evidence from Observations: Reported

List of 2 Events for Episode 1 at Okama

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Explosion	Uncertain
	1622	- - - -	VEI (Explosivity Index)

1620 Confirmed Eruption (Explosive / Effusive) VEI: 2 (?)

Episode 1 | Eruption (Explosive / Effusive)

Okama

1620 - Unknown

Evidence from Observations: Reported

List of 3 Events for Episode 1 at Okama

Start Date	End Date	Event Type	Event Remarks
- - - -	- - - -	Explosion	Uncertain
- - - -	- - - -	Fauna Kill	Terrestrial.
1620	- - - -	VEI (Explosivity Index)

1400 ± 100 years Confirmed Eruption (Explosive / Effusive) VEI: 3

Episode 1 | Eruption (Explosive / Effusive)

Goshiki-dake area, Z-To11 tephra

1400 ± 100 years - Unknown

Evidence from Isotopic: 14C (calibrated)

List of 4 Events for Episode 1 at Goshiki-dake area, Z-To11 tephra

Start Date	End Date	Event Type	Event Remarks
- - - -	- - - -	Explosion
- - - -	- - - -	Phreatic activity	Uncertain
- - - -	- - - -	Ash
1400 ± 100 years	- - - -	VEI (Explosivity Index)

[ 1350 (?) ] Uncertain Eruption

Episode 1 | Eruption (Explosive / Effusive)

Okama

1350 (?) - Unknown

Evidence from Unknown

List of 2 Events for Episode 1 at Okama

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Phreatic activity	Uncertain
	1350 (?)	- - - -	VEI (Explosivity Index)

[ 1331 - 1333 ] Uncertain Eruption

Episode 1 | Eruption (Explosive / Effusive)

Okama

1331 - 1333

Evidence from Unknown

List of 2 Events for Episode 1 at Okama

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Phreatic activity	Uncertain
	1331	- - - -	VEI (Explosivity Index)

1230 Nov 29 (?) Confirmed Eruption (Explosive / Effusive) VEI: 2 (?)

Episode 1 | Eruption (Explosive / Effusive)

Okama

1230 Nov 29 (?) - Unknown

Evidence from Observations: Reported

List of 3 Events for Episode 1 at Okama

Start Date	End Date	Event Type	Event Remarks
- - - -	- - - -	Explosion	weak or small
- - - -	- - - -	Pumice
1230 Nov 29 (?)	- - - -	VEI (Explosivity Index)

1227 Oct (?) Confirmed Eruption (Explosive / Effusive) VEI: 3

Episode 1 | Eruption (Explosive / Effusive)

Okama

1227 Oct (?) - Unknown

Evidence from Observations: Reported

List of 5 Events for Episode 1 at Okama

Start Date	End Date	Event Type	Event Remarks
- - - -	- - - -	Explosion
- - - -	- - - -	Phreatic activity	Uncertain
- - - -	- - - -	Blocks
- - - -	- - - -	Property Damage
1227 Oct (?)	- - - -	VEI (Explosivity Index)

1183 May 28 (?) Confirmed Eruption (Explosive / Effusive) VEI: 2 (?)

Episode 1 | Eruption (Explosive / Effusive)

Okama

1183 May 28 (?) - Unknown

Evidence from Observations: Reported

List of 2 Events for Episode 1 at Okama

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Explosion	Uncertain
	1183 May 28 (?)	- - - -	VEI (Explosivity Index)

0884 (?) Confirmed Eruption (Explosive / Effusive) VEI: 3

Episode 1 | Eruption (Explosive / Effusive)

Okama, Z-To10 tephra?

0884 (?) - Unknown

Evidence from Observations: Reported

List of 3 Events for Episode 1 at Okama, Z-To10 tephra?

Start Date	End Date	Event Type
- - - -	- - - -	Explosion
- - - -	- - - -	Ash
0884 (?)	- - - -	VEI (Explosivity Index)

[ 0773 Nov (?) ] Uncertain Eruption

Episode 1 \| Eruption (Explosive / Effusive)				Okama
0773 Nov (?) - Unknown				Evidence from Unknown

0300 ± 200 years Confirmed Eruption (Explosive / Effusive) VEI: 4

Episode 1 | Eruption (Explosive / Effusive)

Goshiki-dake area, Z-To9 tephra

0300 ± 200 years - Unknown

Evidence from Isotopic: 14C (calibrated)

List of 4 Events for Episode 1 at Goshiki-dake area, Z-To9 tephra

Start Date	End Date	Event Type	Event Remarks
- - - -	- - - -	Explosion
- - - -	- - - -	Phreatic activity	Uncertain
- - - -	- - - -	Ash
0300 ± 200 years	- - - -	VEI (Explosivity Index)

1600 BCE (?) Confirmed Eruption (Explosive / Effusive)

Episode 1 | Eruption (Explosive / Effusive)

Goshiki-dake

1600 BCE (?) - Unknown

Evidence from Isotopic: 14C (calibrated)

List of 2 Events for Episode 1 at Goshiki-dake

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Phreatic activity
	- - - -	- - - -	Ash

2000 BCE ± 500 years Confirmed Eruption (Explosive / Effusive)

Episode 1 | Eruption (Explosive / Effusive)

Goshiki-dake

2000 BCE ± 500 years - Unknown

Evidence from Correlation: Tephrochronology

List of 2 Events for Episode 1 at Goshiki-dake

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Phreatic activity
	- - - -	- - - -	Ash

2300 BCE ± 75 years Confirmed Eruption (Explosive / Effusive)

Episode 1 | Eruption (Explosive / Effusive)

Goshiki-dake area, Z-To8 tephra

2300 BCE ± 75 years - Unknown

Evidence from Isotopic: 14C (calibrated)

List of 2 Events for Episode 1 at Goshiki-dake area, Z-To8 tephra

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Explosion
	- - - -	- - - -	Ash

2600 BCE ± 200 years Confirmed Eruption (Explosive / Effusive)

Episode 1 | Eruption (Explosive / Effusive)

Goshiki-dake area, Z-To7 tephra

2600 BCE ± 200 years - Unknown

Evidence from Isotopic: 14C (calibrated)

List of 2 Events for Episode 1 at Goshiki-dake area, Z-To7 tephra

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Explosion
	- - - -	- - - -	Ash

3350 BCE ± 50 years Confirmed Eruption (Explosive / Effusive)

Episode 1 | Eruption (Explosive / Effusive)

Goshiki-dake area, Z-To6 tephra

3350 BCE ± 50 years - Unknown

Evidence from Isotopic: 14C (calibrated)

List of 2 Events for Episode 1 at Goshiki-dake area, Z-To6 tephra

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Explosion
	- - - -	- - - -	Phreatic activity

3850 BCE ± 200 years Confirmed Eruption (Explosive / Effusive)

Episode 1 | Eruption (Explosive / Effusive)

Goshiki-dake area, Z-To5 tephra

3850 BCE ± 200 years - Unknown

Evidence from Isotopic: 14C (calibrated)

List of 3 Events for Episode 1 at Goshiki-dake area, Z-To5 tephra

Start Date	End Date	Event Type
- - - -	- - - -	Explosion
- - - -	- - - -	Pyroclastic flow
- - - -	- - - -	Ash

4150 BCE ± 200 years Confirmed Eruption (Explosive / Effusive)

Episode 1 | Eruption (Explosive / Effusive)

Goshiki-dake area, Z-To5b tephra

4150 BCE ± 200 years - Unknown

Evidence from Isotopic: 14C (calibrated)

List of 3 Events for Episode 1 at Goshiki-dake area, Z-To5b tephra

Start Date	End Date	Event Type
- - - -	- - - -	Explosion
- - - -	- - - -	Phreatic activity
- - - -	- - - -	Ash

5500 BCE (?) Confirmed Eruption (Explosive / Effusive)

Episode 1 | Eruption (Explosive / Effusive)

Goshiki-dake area

5500 BCE (?) - Unknown

Evidence from Isotopic: 14C (calibrated)

List of 2 Events for Episode 1 at Goshiki-dake area

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Phreatic activity
	- - - -	- - - -	Ash

5600 BCE (?) Confirmed Eruption (Explosive / Effusive)

Episode 1 | Eruption (Explosive / Effusive)

Goshiki-dake, Z-To5a tephra

5600 BCE (?) - Unknown

Evidence from Isotopic: 14C (calibrated)

List of 2 Events for Episode 1 at Goshiki-dake, Z-To5a tephra

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Explosion
	- - - -	- - - -	Ash

7600 BCE (?) Confirmed Eruption (Explosive / Effusive)

Episode 1 | Eruption (Explosive / Effusive)

Goshiki-dake area

7600 BCE (?) - Unknown

Evidence from Isotopic: 14C (calibrated)

List of 2 Events for Episode 1 at Goshiki-dake area

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Phreatic activity
	- - - -	- - - -	Ash

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

Cones

Feature Name

Feature Type

Elevation

Latitude

Longitude

Byobu-dake

Stratovolcano

1817 m

Chuo-Zao

Stratovolcano

1841 m

Fubo-san

Stratovolcano

1705 m

Gando-san

Stratovolcano

Goshiki-dake
Gosiki-dake

Tuff cone

1674 m

Maeeboshi-dake

Stratovolcano

1402 m

Manokami-dake

Stratovolcano

1585 m

Minami-Zao

Stratovolcano

1817 m

Nakamaru-yama

Stratovolcano

1557 m

Nishi-Zao

Stratovolcano

1364 m

Nonomori-yama

Stratovolcano

733 m

Nyodo-san

Stratovolcano

1600 m

Nyudo-san

Cone

1640 m

Omori-yama

Cone

820 m

Onmae-dake

Stratovolcano

1705 m

Ryuzan

Stratovolcano

1364 m

Sanpokojin-san

Stratovolcano

1683 m

Sarukura-yama

Stratovolcano

873 m

Sugigamine

Stratovolcano

1745 m

Ushiroeboshi-dake

Stratovolcano

1666 m

Yokokura-yama

Stratovolcano

1152 m

Craters

Feature Name

Feature Type

Elevation

Latitude

Longitude

Okama
Goshiki-numa
Zao-numa

Crater

1674 m

Domes

Feature Name

Feature Type

Elevation

Latitude

Longitude

Jizo-san

Dome

1694 m

Katta-dake

Dome

1795 m

Kumano-dake

Dome

1841 m

38° 8' 26.00" N

140° 26' 34.00" E

Torikabuto-yama

Dome

1401 m

Thermal

Feature Name

Feature Type

Elevation

Latitude

Longitude

Aone Spa

Thermal

520 m

Gaga Spa

Thermal

800 m

Kamoshika

Thermal

1150 m

Togatta Hot Spring

Hot Spring

Zao Spa

Thermal

840 m

Photo Gallery

Okama crater of Goryudake within the Zaozan volcanic complex is shown here from the E. The 360-m-wide lake is about 60 m deep and is the site of many recorded eruptions. White mud deposited on the lake floor is periodically disturbed by gas emission, changing the color of the water.

Copyrighted photo by Yoshihisa Kawanabe (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/).

Smithsonian Sample Collections Database

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

External Sites

Copernicus Browser

The Copernicus Browser replaced the Sentinel Hub Playground browser in 2023, to provide access to Earth observation archives from the Copernicus Data Space Ecosystem, the main distribution platform for data from the EU Copernicus missions.

MIROVA

Middle InfraRed Observation of Volcanic Activity (MIROVA) is a near real time volcanic hot-spot detection system based on the analysis of MODIS (Moderate Resolution Imaging Spectroradiometer) data. In particular, MIROVA uses the Middle InfraRed Radiation (MIR), measured over target volcanoes, in order to detect, locate and measure the heat radiation sourced from volcanic activity.

MODVOLC Thermal Alerts

Using infrared satellite Moderate Resolution Imaging Spectroradiometer (MODIS) data, scientists at the Hawai'i Institute of Geophysics and Planetology, University of Hawai'i, developed an automated system called MODVOLC to map thermal hot-spots in near real time. For each MODIS image, the algorithm automatically scans each 1 km pixel within it to check for high-temperature hot-spots. When one is found the date, time, location, and intensity are recorded. MODIS looks at every square km of the Earth every 48 hours, once during the day and once during the night, and the presence of two MODIS sensors in space allows at least four hot-spot observations every two days. Each day updated global maps are compiled to display the locations of all hot spots detected in the previous 24 hours. There is a drop-down list with volcano names which allow users to 'zoom-in' and examine the distribution of hot-spots at a variety of spatial scales.

WOVOdat
   Single Volcano View
   Temporal Evolution of Unrest
   Side by Side Volcanoes

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.

GVMID Data on Volcano Monitoring Infrastructure The Global Volcano Monitoring Infrastructure Database GVMID, is aimed at documenting and improving capabilities of volcano monitoring from the ground and space. GVMID should provide a snapshot and baseline view of the techniques and instrumentation that are in place at various volcanoes, which can be use by volcano observatories as reference to setup new monitoring system or improving networks at a specific volcano. These data will allow identification of what monitoring gaps exist, which can be then targeted by remote sensing infrastructure and future instrument deployments.

Volcanic Hazard Maps

The IAVCEI Commission on Volcanic Hazards and Risk has a Volcanic Hazard Maps database designed to serve as a resource for hazard mappers (or other interested parties) to explore how common issues in hazard map development have been addressed at different volcanoes, in different countries, for different hazards, and for different intended audiences. In addition to the comprehensive, searchable Volcanic Hazard Maps Database, this website contains information about diversity of volcanic hazard maps, illustrated using examples from the database. This site is for educational purposes related to volcanic hazard maps. Hazard maps found on this website should not be used for emergency purposes. For the most recent, official hazard map for a particular volcano, please seek out the proper institutional authorities on the matter.

IRIS seismic stations/networks

Incorporated Research Institutions for Seismology (IRIS) Data Services map showing the location of seismic stations from all available networks (permanent or temporary) within a radius of 0.18° (about 20 km at mid-latitudes) from the given location of Zaozan [Zaosan]. Users can customize a variety of filters and options in the left panel. Note that if there are no stations are known the map will default to show the entire world with a "No data matched request" error notice.

UNAVCO GPS/GNSS stations

Geodetic Data Services map from UNAVCO showing the location of GPS/GNSS stations from all available networks (permanent or temporary) within a radius of 20 km from the given location of Zaozan [Zaosan]. Users can customize the data search based on station or network names, location, and time window. Requires Adobe Flash Player.

DECADE Data

The DECADE portal, still in the developmental stage, serves as an example of the proposed interoperability between The Smithsonian Institution's Global Volcanism Program, the Mapping Gas Emissions (MaGa) Database, and the EarthChem Geochemical Portal. The Deep Earth Carbon Degassing (DECADE) initiative seeks to use new and established technologies to determine accurate global fluxes of volcanic CO₂ to the atmosphere, but installing CO₂ monitoring networks on 20 of the world's 150 most actively degassing volcanoes. The group uses related laboratory-based studies (direct gas sampling and analysis, melt inclusions) to provide new data for direct degassing of deep earth carbon to the atmosphere.

Large Eruptions of Zaozan [Zaosan]

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).

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).