Hachijojima

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  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 33.137°N
  • 139.766°E

  • 854 m
    2801 ft

  • 284050
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number

4 September-10 September 2002

In late August, fewer than ten earthquakes occurred at Hachijo-jima per hour and ground deformation had returned to normal levels. On 27 August, very long-period signals were detected near Hachijo-jima. The signals were felt widely on the southern coast of Honshu. The hypocenter of a high-frequency earthquake preceded by a very long-period signal was located NW offshore of the volcano.

Source: Japan Meteorological Agency (JMA) via the Volcano Research Center

Index of Weekly Reports


2002: August | September

Weekly Reports


4 September-10 September 2002

In late August, fewer than ten earthquakes occurred at Hachijo-jima per hour and ground deformation had returned to normal levels. On 27 August, very long-period signals were detected near Hachijo-jima. The signals were felt widely on the southern coast of Honshu. The hypocenter of a high-frequency earthquake preceded by a very long-period signal was located NW offshore of the volcano.

Source: Japan Meteorological Agency (JMA) via the Volcano Research Center


21 August-27 August 2002

Seismicity that began to increase at Hachijo-jima on 13 August (when 16 earthquakes were recorded) began to decrease on 20 August (less than 10 earthquakes were recorded). The earthquake's hypocenters migrated from NW to SE, roughly parallel to the long axis of the island. Hypocenters of low-frequency earthquakes that occurred on the morning of 21 August were located near the 13-15 August swarm's hypocenters.

Source: Japan Meteorological Agency (JMA) via the Volcano Research Center


14 August-20 August 2002

JMA reported that seismicity increased at Hachijo-jima beginning on 13 August around 1600. By 1700 that day 16 earthquakes were felt, with a maximum magnitude of 3. The hypocenters were located ~2 km off of the island's W shore at depths of 5-15 km, depending on assumed seismic-wave velocity models. During the afternoon of the 15th, the earthquakes migrated to the N, without a clear change in depth. By the 16th, volcanic tremor-like waveforms were also recorded. By the evening of the 16th seismicity began to decrease. JMA stated that the overall increase in seismicity might not lead directly to an eruption, though seismicity may continue at a similar level. According to the Geographical Survey Institute, GPS measurements revealed in the center of the island there was 5-6 cm of movement to the E and 10 cm of uplift until about 1500.

Source: Japan Meteorological Agency (JMA) via the Volcano Research Center


Index of Monthly 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.

07/2002 (BGVN 27:07) Seismic swarms during August 2002


Contents of Monthly Reports

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

All times are local (= UTC + 9 hours)

07/2002 (BGVN 27:07) Seismic swarms during August 2002

The Japanese Meteorological Agency (JMA) reported that at around 1600 on 13 August 2002 seismic swarms began on Hachijo-jima island (figure 1). The island lies ~300 km S of Tokyo in the Izu island chain. A total of 16 earthquakes were felt by 1700 on 15 August. Hypocenters were located ~2 km off the W shore of the central part of the island, at depths of 5-15 km (according to seismic-wave velocity models) (figure 2). The earthquakes deepened and started migrating to the N, in the direction of Nishi-yama, on the morning on 15 August. Five seismic stations are located on the inhabited island.

Figure 1. Map showing the elongated, NW-SE-trending Hachijo-jima island, consisting of two small Quaternary stratovolcanoes, Higashi-yama to the SE and Nishi-yama to the NW. The small volcanic island of Ko-jima lies several kilometers to the W of Hachijo-jima. Courtesy of Volcano Research Center.
Figure 2. Hypocenters of volcanic earthquakes at Hachijo-jima during 13-15 August 2002 (as of 2000 on 15 August). Sites of seismic stations are shown on figure 13. Courtesy of Shin'ichi Sakai, JMA.

On 16 August JMA reported that high seismicity continued at Hachijo-jima volcano, when volcanic tremor-like waves were recorded. JMA reported that the hourly number of earthquakes had been over 20 since the evening of 13 August; the peak occurred on the morning of 15 August (~250 earthquakes per hour). As of 1500 on 16 August, 22 earthquakes had been felt. Seismic activity began to decrease during the evening of 16 August. JMA reported that during 16-17 August, less than 20 earthquakes occurred per hour. JMA installed two seismometers temporarily on the island on 17 August. JMA released a statement saying that the present seismic activity may continue at the same level for some time without an eruption. The Geographical Survey Institute reported that the GPS station located in the center of the island had migrated 5-6 cm to the E and had been uplifted 10 cm by 1500 on 16 August.

Seismicity around Hachijo-jima decreased by 21 August. Since the afternoon of 20 August, less than 10 earthquakes occurred per hour. Hypocenters had migrated to the NW from the original site of earthquake concentration, advancing parallel to the long axis of the island. Low-frequency earthquakes continued on 21 August; hypocenters were located near the first swarms of 13-15 August.

Information Contacts: Hitoshi Yamasato, Japanese Meteorological Agency (JMA), Volcanological Division, 1-3-4 Ote-machi, Chiyoda-ku, Tokyo 100, Japan (URL: http://www.kishou.go.jp/english/, Email: tkanno@met.kishou.go.jp, yamasato@met.kishou.go.jp); Shin'ichi Sakai, Volcano Research Center (VRC), Earthquake Research Institute (ERI), University of Tokyo, 113-0032 1-1-1, Yayoi, Bunkyo-ku, Tokyo (URL: http://hakone.eri.u-tokyo.ac.jp/, Email:coco@eri.u-tokyo.ac.jp); Geographical Survey Institute (GSI), Kitasato 1, Tsukuba Ibaraki, 305-0811 Japan (URL: http://www.gsi.go.jp/, Email:intex@gsi.go.jp).

Hachijojima, in the central Izu Islands about 300 km S of Tokyo, consists of two small Quaternary dominantly basaltic stratovolcanoes forming an elongated NW-SE-trending island. The eroded Pleistocene-to-Holocene Higashiyama volcano occupies the SE end of the 14-km-long island, and the symmetrical Holocene Nishiyama volcano the NW end. Parasitic cones occur on the SE flank of Nishiyama. The small volcanic island of Kojima lies several kilometers W of Hachijojima. Growth of Higashiyama began several tens of thousands of years ago, and included the formation of two small calderas. The initial submarine and early subaerial eruptions of Nishiyama took place from 10,000 to 8000 years before present (BP). Its latest major activity, from the early Holocene until about 4000 BP, was restricted to flank eruptions. Historical eruptions of Hachijojima, recorded since the 15th century, have been restricted to the summit of Nishiyama and a submarine vent of unknown location.

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

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
[ 1707 ] [ Unknown ] Uncertain 2  
1606 Jan 23 Unknown Confirmed 2 Historical Observations Submarine flank
1605 Oct 27 Unknown Confirmed 2 Historical Observations Nishi-yama SE flank
1518 Feb 1523 Confirmed 2 Historical Observations Nishi-yama
1487 Dec 7 Unknown Confirmed 2 Historical Observations Nishi-yama
0850 ± 200 years Unknown Confirmed   Radiocarbon (corrected) Nishi-yama summit and SE flank
0150 BCE ± 50 years Unknown Confirmed   Radiocarbon (corrected) Nishi-yama
0350 BCE ± 500 years Unknown Confirmed 3 Tephrochronology NW flank of Higashi-yama
1150 BCE ± 700 years Unknown Confirmed   Tephrochronology SE flank of Nishi-yama (Kanda-yama)
1250 BCE ± 800 years Unknown Confirmed   Tephrochronology Nishi-yama
2050 BCE (?) Unknown Confirmed 5 Tephrochronology SE of Nishi-yama, NE of Higashi-yama
2450 BCE ± 500 years Unknown Confirmed 4 Tephrochronology Nishi-yama
2550 BCE ± 500 years Unknown Confirmed 3 Tephrochronology S flank of Higashi-yama (Myohoji)
2700 BCE ± 100 years Unknown Confirmed 3 Radiocarbon (corrected) Between Nishi-yama & Higashi-yama
3350 BCE ± 1300 years Unknown Confirmed   Tephrochronology Nishi-yama
4650 BCE (?) Unknown Confirmed 5 Tephrochronology Nishi-yama
5020 BCE ± 370 years Unknown Confirmed 3 Tephrochronology Higashi-yama south flank
7650 BCE ± 3000 years Unknown Confirmed   Tephrochronology Nishi-yama
8020 BCE ± 2640 years Unknown Confirmed 4 Tephrochronology Nishi-yama

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
Hachijo-jima Nishi-yama | Hatizyo-zima Nisi-yama | Hatizyo-Huzi | Hachijo-Fuji | Hachijo-jima


Cones
Feature Name Feature Type Elevation Latitude Longitude
Hachiman-yama Cone 225 m 33° 4' 0" N 139° 48' 0" E
Higashi-hakuunzan Cone 608 m 33° 6' 0" N 139° 50' 0" E
Higashi-yama
    Higasi-yama
Stratovolcano 701 m 33° 5' 0" N 139° 49' 0" E
Ko-jima
    Ko-zima
Stratovolcano 617 m 33° 8' 0" N 139° 42' 0" E
Myohoji Cone 33° 4' 0" N 139° 49' 0" E
Nakanogo Cone 33° 4' 0" N 139° 49' 0" E
Nishi-yama
    Nisi-yama
Stratovolcano 854 m 33° 8' 0" N 139° 46' 0" E


Craters
Feature Name Feature Type Elevation Latitude Longitude
Kando-yama Crater 195 m 33° 7' 0" N 139° 48' 0" E
Mihara Pleistocene caldera 701 m 33° 5' 0" N 139° 49' 0" E
Nishi-Hakuunzan Pleistocene caldera 635 m 33° 5' 0" N 139° 49' 0" E
Oana Crater 854 m 33° 8' 0" N 139° 46' 0" E
Conical Nishi-yama volcano, seen here from the older cone Higashi-yama, forms the NW part of elongated Hachijo-jima island. The island's airport and its largest town occupy the flanks of Nishi-yama. The small volcanic island of Ko-jima (upper left) lies several km to the west of Hachijo-jima. The latest major activity of Nishi-yama, from the early Holocene until about 4000 years ago, was restricted to flank eruptions.

Photo by Ichio Moriya (Kanazawa University).
The oldest of two volcanoes forming Hachijo-jima, Higashi-yama, lies at the SE part of the island. Activity at Higashi-yama, seen here from the slopes of Nishi-yama, dates back to the Pleistocene, and the slopes of the volcano are extensively gullied. The last eruption of Higashi-yama took place about 4000 years ago, depositing the Mizumiya pumice fall deposit

Photo by Ichio Moriya (Kanazawa University).

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.

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/.

Suga K, 1994. Volcanic history of Higashiyama, Hachijojima. Bull Volc Soc Japan (Kazan), 39: 13-24.

Tsukui M, Hoshino K, 2002. Magmatic differentiation of Hachijo-Nishiyama volcano, Izu Islands, Japan. Bull Volc Soc Japan (Kazan), 47: 57-72 (in Japanese with English abs).

Tsukui M, Moriizumi M, Suzuki M, 1991. Eruptive history of the Higashiyama volcano, Hachijo Island during the last 22,000 years. Bull Volc Soc Japan (Kazan), 36: 345-356 (in Japanese with English abs).

Volcano Types

Stratovolcano(es)
Caldera(s)
Lava dome
Pyroclastic cone(s)

Tectonic Setting

Subduction zone
Oceanic crust (< 15 km)

Rock Types

Major
Basalt / Picro-Basalt
Andesite / Basaltic Andesite

Population

Within 5 km
Within 10 km
Within 30 km
Within 100 km
11,275
13,560
13,564
14,082

Affiliated Databases

Large Eruptions of Hachijojima 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.