Fukutoku-Oka-no-Ba

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  • 24.285°N
  • 141.481°E

  • -29 m
    -95 ft

  • 284130
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Most Recent Weekly Report: 3 February-9 February 2010


According to news articles, JMA reported Surtseyan explosions from Fukutoku-Okanoba, 5 km NE of the island of Minami-Iwo-jima, on 3 February. Steam-and-ash plumes rose 100 m a.s.l. and the surrounding sea turned yellow-green. Video footage of the event was captured by people aboard a Japanese Coast Guard patrol boat. One article stated that the sea in the area had regularly changed colors since the 1950s, most recently in December 2009.

Sources: ITN News, The Mainichi Daily News


Most Recent Bulletin Report: February 2010 (BGVN 35:02)


Airborne ash and cloudy water during 3 February 2010 eruption

The submarine volcano Fukutoku-Okanoba, frequently the source of discolored water (e.g., BGVN 32:01 and 30:11), erupted on the morning of 3 February 2010, sending a plume of ash and steam 100 m into the air (figure 7) and turning the surrounding ocean a yellow-green color (figure 8). Additional observations of discolored water have been frequently documented in JMA reports since November 2006 (BGVN 32:01). More details of that activity, from January 2007 through December 2009, will be provided in a following Bulletin.

Figure 7. Aerial photograph of an ash plume rising from the ocean over Fukutoku-Okanoba on 3 February 2010. Photograph courtesy Japan Coast Guard.
Figure 8. During a lull in the 3 February 2010 eruption of Fukutoku-Okanoba, some water above the summit bubbled and took on yellowish-green colors. Aerial photograph courtesy Japan Coast Guard.

The February 2010 eruption was discovered at about 0745 by the Japan Coast Guard patrol boat Yashima on a routine survey. The crew first noticed "smoke" coming from the surface of the ocean ~ 5 km NNE of the island of Minami-Iwo-jima. The crew also heard a blast and felt its pressure wave. The Yashima continued to monitor the site from a safe distance.

Satellite imagery provided evidence that the activity persisted for at least several days. On 9 February the underwater plume appears as a complex shape N of the volcano (figure 9). Two days later, on 11 February, the plume was spread W of the volcano (figure 10).

Figure 9. On 9 February 2010, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite captured this false-color image of the ocean around Fukutoku-Okanoba volcano. Water colored by the underwater plume appears lighter in contrast to the surrounding water. The discolored water initially formed a rough V-shape N of the summit. Courtesy of NASA Earth Observatory.
Figure 10. Satellite image taken 11 February 2010 of the ocean around Fukutoku-Okanoba volcano. The water colored by the plume forms a V-shape W of the volcano summit. This true-color image (enhanced for publication) was taken by the Advanced Land Imager (ALI) on NASA's EO-1 satellite. Courtesy of NASA Earth Observatory.

JMA isssued eruption alerts for 9 March and 8 April 2010. This suggests that the eruption continued into April.

Information Contacts: Japan Meteorological Agency, 1-3-4 Otemachi, Chiyoda-ku, Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/jma/indexe.html); NASA Earth Observatory (URL: http://earthobservatory.nasa.gov/).

Index of Weekly Reports


2010: February
2005: June

Weekly Reports


3 February-9 February 2010

According to news articles, JMA reported Surtseyan explosions from Fukutoku-Okanoba, 5 km NE of the island of Minami-Iwo-jima, on 3 February. Steam-and-ash plumes rose 100 m a.s.l. and the surrounding sea turned yellow-green. Video footage of the event was captured by people aboard a Japanese Coast Guard patrol boat. One article stated that the sea in the area had regularly changed colors since the 1950s, most recently in December 2009.

Sources: ITN News; The Mainichi Daily News


29 June-5 July 2005

On the evening of 2 July, members of the Japan Coast Guard observed a steam plume rising ~1 km above the sea near the island of Minami-Iwo-jima. On 3 July, JMA confirmed that a small-scale eruption had occurred at the submarine volcano Fukutoku-Okanoba, prompting the Japan Coast Guard to issue a warning against sailing in the area. Observers saw rock and mud rising to the sea's surface near the volcano and a ~1-square-km area of water that had turned orange-brown. As of 4 July, a new island had not formed.

Sources: Daily Yomiuri News; Reuters; Associated Press


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.

03/1975 (CSLP 24-24) Eruption building new island

01/1977 (NSEB 02:01) Possible submarine eruption in December 1974

04/1977 (NSEB 02:04) Water discoloration observed during August 1976

08/1977 (NSEB 02:08) Sea surface discoloration in May

05/1978 (SEAN 03:05) Water discoloration observed October-December 1977 and January 1978

03/1979 (SEAN 04:03) Sea water discoloration

07/1979 (SEAN 04:07) Discolored water observed in 1978 and 1979

04/1980 (SEAN 05:04) Discolored water in late 1979 and early 1980

11/1980 (SEAN 05:11) Discolored water seen during April-July 1980

12/1980 (SEAN 05:12) Water discoloration observed in November and December 1980

10/1981 (SEAN 06:10) Frequent water discoloration observed during January-October 1981

09/1982 (SEAN 07:09) Discolored water observed on flights during December 1981-June 1982

03/1984 (SEAN 09:03) Discolored water observed on 12 days in 1983

10/1985 (SEAN 10:10) Discolored water

11/1985 (SEAN 10:11) Water discoloration observed frequently during December 1983-October 1985

12/1985 (SEAN 10:12) Explosive eruption builds island

01/1986 (SEAN 11:01) New island formed

02/1986 (SEAN 11:02) New island erodes; floating pumice

03/1986 (SEAN 11:03) January island eroded below sea level

06/1986 (SEAN 11:06) Discolored sea water

07/1987 (SEAN 12:07) Submarine eruptions; floating pumice

09/1987 (SEAN 12:09) Discolored and spouting seawater

10/1987 (SEAN 12:10) Pale green discolored water

10/1988 (SEAN 13:10) Discolored water

07/1989 (SEAN 14:07) Thermal activity discolors sea water

12/1990 (BGVN 15:12) Frequent observations of discolored water

04/1991 (BGVN 16:04) Water discoloration during one of five overflights

09/1991 (BGVN 16:09) Water discoloration over submarine vent

10/1991 (BGVN 16:10) Discolored water

10/1992 (BGVN 17:10) Pumice ejected by submarine eruption

11/1992 (BGVN 17:11) Smaller zone of discolored water; no new pumice

12/1993 (BGVN 18:12) Discolored water observed over volcano four times in 1993

12/1995 (BGVN 20:11) Discolored seawater

01/1996 (BGVN 21:01) Discolored seawater observed for the second time in three months

03/1996 (BGVN 21:03) Emission of colored water and long discolored aqueous plumes

04/1996 (BGVN 21:04) Yellowish-brown discolored seawater seen again

05/1996 (BGVN 21:05) Discolored seawater

10/1996 (BGVN 21:10) Water discoloration from submarine volcano observed in September

01/1997 (BGVN 22:01) Submarine venting continues to discolor seawater

11/2005 (BGVN 30:11) July 2005 submarine eruption; discolored water and debris

01/2007 (BGVN 32:01) Discolored water attributed to submarine volcanism

02/2010 (BGVN 35:02) Airborne ash and cloudy water during 3 February 2010 eruption




Bulletin Reports

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


03/1975 (CSLP 24-24) Eruption building new island

Card 2130 (28 March 1975) Eruption building new island

The following cable was received from Fleet Weather Central, Guam. "On 25 March 1975 a U.S. Air Force reconnaissance flight operating out of Guam sighted an area of oceanic volcanic activity 32 km S of Iwo Jima. The sighting was described as possibly an island in the formative stages. Photographs were taken by the crew. Fleet Weather Central, Guam, is closely watching weather satellite coverage for the area for any signs of further activity."

Information Contacts: Fleet Weather Central, U.S. Air Force, Guam, Mariana Islands.

01/1977 (NSEB 02:01) Possible submarine eruption in December 1974

[A table of possible submarine eruptions based on aerial observations of water discoloration by the Japanese Maritime Safety Agency included an entry for 24.28°N, 141.50°E, in December 1974. This location is very close to Fukutoku-Okanoba. In March 1975 another observation was listed at 24.42°N, 141.32°E; this is ~25 km NW of Fukutoku-Okanoba and ~36 km S of Iwo-jima.]

Information Contacts: AFP; U.S. Defense Mapping Agency.

04/1977 (NSEB 02:04) Water discoloration observed during August 1976

[A report of surface discoloration in March was removed at JMA's request.] The last reported activity in this area was a [green] discoloration in August 1976.

Information Contacts: JMA, Tokyo.

08/1977 (NSEB 02:08) Sea surface discoloration in May

Sea surface discoloration was observed from the air on 1, [12, 13, 16, 17, 21, 22, and 25 May].

Information Contacts: JMA, Tokyo; D. Shackelford, CA.

05/1978 (SEAN 03:05) Water discoloration observed October-December 1977 and January 1978

Discoloration was observed on 14 October 1977, 15 and 25 November 1977, 8 and 23 December 1977, and 10, 24, and 25 January 1978.

Information Contacts: JMA, Tokyo.

03/1979 (SEAN 04:03) Sea water discoloration

Aerial reconnaissance by the JMSA in late January showed slight discoloration of the ocean around this volcano, at 24.30°N, 141.48°E.

Information Contacts: Y. Sawada, Meteorolgical Research Institute, Tokyo; D. Shackelford, CA.

07/1979 (SEAN 04:07) Discolored water observed in 1978 and 1979

Activity has been observed at six submarine volcanoes in the Volcano Island chain in 1978 and 1979 (figure 1). Discolored water has often been visible . . . during frequent overflights by JMSDF and JMSA aircraft. [Discolored water was noted, in an included table of observations, by almost every overflight during January 1978-July 1979 (see table 1 below).]

Figure 1. Map showing Japan and the Volcano Island chain. Volcanoes active in 1978 or 1979 are indicated by black squares. Courtesy of JMA.

Information Contacts: JMSA, Tokyo; JMA, Tokyo.

04/1980 (SEAN 05:04) Discolored water in late 1979 and early 1980

The Japan Maritime Safety Agency continues frequent monitoring flights over three known submarine volcanoes. [Discolored water at Fukutoku-Okanoba was seen during September 1979-March 1980 (see table 1 below).]

Information Contacts: JMSA, Tokyo; JMA, Tokyo.

11/1980 (SEAN 05:11) Discolored water seen during April-July 1980

The Japan Maritime Safety Agency (JMSA) continues frequent monitoring flights over several known submarine volcanoes. [Discolored water at Fukutoku-Okanoba was seen during April-July 1980 (see table 1 below).]

Information Contacts: JMSA, Tokyo; JMA, Tokyo.

12/1980 (SEAN 05:12) Water discoloration observed in November and December 1980

The Japanese Maritime Safety Agency (JMSA) continues frequent aerial monitoring of several known submarine volcanoes. [Discolored water was seen at Fukutoku-Okanoba on 14 November and 18 December 1980 (see table 1 below).]

Information Contacts: JMSA, Tokyo; JMA, Tokyo.

10/1981 (SEAN 06:10) Frequent water discoloration observed during January-October 1981

The Japan Maritime Safety Agency (JMSA) continues frequent monitoring flights over several known submarine volcanoes. [Discolored water at Fukutoku-Okanoba was specifically noted, in an included table of observations, on 9 and 29 January, 12 and 20 February, 12, 13, and 16 March, 20 April, 16, 17, and 22 July, 17 August, and 17 September 1981 (see table 1 below).]

Information Contacts: JMSA, Tokyo; JMA, Tokyo.

09/1982 (SEAN 07:09) Discolored water observed on flights during December 1981-June 1982

JMSA [and JMSDF have] continued frequent monitoring flights over several known submarine volcanoes (table 1). On almost all overflights discolored sea water was seen around Fukutoku-Okanoba, the most active submarine volcano in this area.

Table 1. Volcanic activity at three sites (Fukutoku-Okanoba, Minami-Hiyoshi, and Fukujin) in the Volcano Islands, January 1978-December 1982, detected by JMSA and JMSDF monitoring flights. Activity indicated as D = Discolored water; N = No discolored water, - = No overflight, ? = not reported. This table combines data from reports in 1979 (4:7), 1980 (5:4, 5:11, and 5:12), 1981 (6:10), and 1982 (7:9, plus additional data not published in the Bulletin).

    Date         Fukutoku-Okanoba    Minami-Hiyoshi    Fukujin

    10 Jan 78           D                  N               D
    24 Jan 78           D                  N               D
    25 Jan 78           D                  -               D
    26 Jan 78           -                  D               D
    23 Feb 78           D                  D               N
    24 Mar 78           D                  D               D
    13 Apr 78           D                  N               N
    25 May 78           D                  N               N
    28 Jun 78           D                  -               -
    29 Jun 78           D                  N               N
    25 Aug 78           D                  N               D
    24 Oct 78           N                  N               N
    15 Nov 78           D                  -               -
    16 Nov 78           D                  N               N
    14 Dec 78           D                  N               N

    11 Jan 79           D                  -               -
    24 Jan 79           D                  N               N
    08 Feb 79           D                  N               N
    27 Mar 79           D                 [N]              -
    26 Apr 79           D                  N               D
    15 Jun 79           N                  N               N
    11 Jul 79           N                  -               -
    12 Jul 79           D                  N               D
    24 Aug 79           N                  N               -
    09 Sep 79           D                  -               -
    13 Sep 79           D                  N               N
    25 Oct 79           D                  N               D
    08 Nov 79           D                  N               D
    12 Dec 79           D                  N               D

    29 Jan 80           -                  -               D
    15 Feb 80           D                  N               D
    19 Mar 80           D                  N               D
    24 Apr 80           D                  N               N
    12 May 80           D                  -               D
    16 Jun 80           D                  N               N
    07 Jul 80           D                  -               -
    08 Jul 80           D                  N               N
    14 Jul 80           D                  N               N
    18 Aug 80           N                  N               N
    04 Sep 80           N                  N               N
    21 Oct 80           N                  N               N
    14 Nov 80           D                  N               N
    18 Dec 80           D                  N               N

    07 Jan 81           -                  -               D
    08 Jan 81           -                  -               D
    09 Jan 81           D                  N               N
    29 Jan 81           D                  -               -
    12 Feb 81           D                 [-]              -
    20 Feb 81           D                 [N]              N
    12 Mar 81           D                 [-]              -
    13 Mar 81           D                  N               N
    16 Mar 81           D                  N               N
    20 Apr 81           D                  N               N
    17 Jun 81           N                  N               N
    16 Jul 81           D                  -               -
    17 Jul 81           D                 [N]             [N]
    22 Jul 81           D                  N               N
    17 Aug 81           D                  N               N
    17 Sep 81           D                  N               N
    19 Oct 81           N                  N               N
    11 Nov 81           N                  N              [-]
    21 Dec 81           D                  N               N

    12 Jan 82           -                  -               D
    19 Jan 82           D                  N               D
    09 Feb 82           D                  N               N
    28 Feb 82           D                  -               -
    16 Mar 82           D                  N               D
    01 Apr 82           D                  -               N
    02 Apr 82           D                  N               N
    16 Apr 82           D                  N               N
    14 May 82           D                  N               N
    16 Jun 82           D                  N               N
    22 Jun 82           D                  -               -
    13 Jul 82           D                  ?               N
    20 Aug 82           D                  ?               N
    27 Sep 82           D                  ?               N
    13 Oct 82           D                  ?               N
    17 Nov 82           D                  ?               N
    15 Dec 82           D                  ?               D

Information Contacts: JMA, Tokyo.

03/1984 (SEAN 09:03) Discolored water observed on 12 days in 1983

Frequent monitoring of several known submarine volcanoes has continued. . . . [Discolored water was observed at Fukutoku-Okanoba in 1983 on 14 January, 2 and 15 February, 3 and 15-16 March, 24 May, 16 June, 20 July, 25 October, 11 November, and 12 December; and was not visible 12 July, 25 August, and 13 September.]

Information Contacts: JMA, Tokyo.

10/1985 (SEAN 10:10) Discolored water

A milky white discoloration, about 100 m in diameter, was observed on 17 September and discoloration was noted again on 17 October.

Information Contacts: JMA, Tokyo.

11/1985 (SEAN 10:11) Water discoloration observed frequently during December 1983-October 1985

JMSA has continued frequent aerial monitoring of several known submarine volcanoes. Volcanic activity has often been observed at Fukutoku-Okanoba during overflights since late 1983 . . . . Discolored water was observed at Fukutoku-Okanoba on: 21 December 1983; 30 January, 23 February, 15 March, 6 and 23 April, 18 May, 9 June, 10 July, 1 August, 6 September, and 16 November 1984; and 14 February, 15 March, 17 April, 14 May, 17 September, and 17 October 1985; and was not visible 26 September, 24 October, and 12 December 1984.

[Additional water discoloration in 1985 was reported (Bulletin of Volcanic Eruptions no. 25, 1988) on 14 June, 17 July, 13 August, 14 November, and 23 December.]

Information Contacts: JMA, Tokyo.

12/1985 (SEAN 10:12) Explosive eruption builds island

On 18 January, fishermen observed a large white plume rising to more than 3 km altitude and lava being ejected to about 300 m height form the vicinity of the submarine volcano Fukutoku-Okanoba. The eruption was first evident on infrared imagery from the Japanese GMS geostationary weather satellite on 18 January at 2100. Japan Maritime Self-Defense Force personnel stationed on Iwo-Jima, about 50 km from Fukutoku-Okanoba, observed a 4-km eruption cloud the next day at 1630. The Japan Maritime Safety Agency's survey ship Takuyo found a new island about 5 km NE of Minami Iwo Jima (south Iwo Jima) the morning of 21 January. The new island, about 700 m long and 300 m wide, extended about 15 m above sea level. Lava was being ejected to about 300 m height. As of 21 January, floating pumice had drifted 60 km to the SE.

Information Contacts: JMA, Tokyo; UPI; AP

01/1986 (SEAN 11:01) New island formed

An eruption . . . built a small island in mid-January. Only milky blue discolored sea water was observed near the volcano on 16 January at about 1200. By 18 January at 2000, eruptive activity was frequent, producing a dark plume, seen from a fishing boat, that reached 3,000-4,000 m height. An hour later the plume was evident on an image from Japan's GMS satellite. The next day at about 1630, airborne radar detected a plume rising to 4,000 m above sea level. On 20 January at 0440, radar on the JMSA's survey ship RV Takuyo showed an island-like image. A gray plume rose to 2,000 m altitude at 0550.

A new island was recognized by observers on the RV Takuyo at 0630. A 50-m vent at the NW edge of the new island ejected plumes and sea water. Continuous observations were made until about 1000. The island was ~700 m long, 500 m wide, and 15 m high (figure 2). A vent near its E edge remained below sea level, ejecting black incandescent rocks as much as 10 m in diameter. Grayish brown pumice had drifted as much as 18 km NE from the vent. Discolored sea water surrounded the island and extended 22 km NE from the vent. The sea water was greenish near the island, gradually becoming greenish yellow or pale blue farther from the vent.

Figure 2. Sketch maps of the new island and associated vent and plume at Fukutoku-Okanoba, 20-23 January 1986. Courtesy of JMA.

At 1122 a dark plume containing incandescent rocks to 10 m in diameter rose 1,200-1,300 m above sea level; between 1250 and 1400 a vapor plume rose to 3,000 m. There was a zone of discolored water ~45 km long and 2-3 km wide. Between 1450 and 1550, explosions occurred at about 20-minute intervals, expelling dark plumes that rose ~1,200-1,700 m. Between 1600 and sunset, 90 weak to moderate explosions ejected plumes to 100-1,000 m height. Volcanic flame was occasionally seen within dark plumes at night.

The next morning at 0800 explosions produced small plumes (<50 m high) at intervals of 1-2 minutes. At 1223, a large explosion was seen; volcanic flame reached 1,500 m above sea level, roughly half of the plume's height. At 1300 the island was flat and crescent-shaped, covered with ash and pumice but no lava flow. The outer arc of the crescent was a portion of a circle ~700 m in diameter having a center that roughly coincided with the position of the active vent, which was ~300 m in diameter (figures 3 and 4). An area of thin yellow or green discoloration extended SSE to 2 km from the island. Pumice drifted E and S.

Figure 3. Photograph of the new island and eruption plume at Fukutoku-Okanoba on 21 January 1986 at about 1400. The conical island in the right background is Minami-Iwo-jima. Photo by G. Iwashita, JMA.
Figure 4. Photograph of the new island and eruption plume at Fukutoku-Okanoba on 21 January 1986 at about 1600. Photo by G. Iwashita, JMA.

By the morning of the 22nd explosive activity had subsided; no plumes were seen for the rest of the month. Erosion of the shoreline of the new island was evident early the next day. However, at 1300 outflow of discolored sea water suggested that the submarine vent, 80 m in diameter, was still active ~400 m E of the island.

The island, covered with gray ash, was ~500 m in length and had a maximum width of 200 m. During the morning of 25 January, dense blue discoloration was seen around and E of the island and had drifted somewhat eastward, to ~9 km from the vent. On the 29th the island's size was estimated at ~600 m long, ~400 m wide and ~10 m high (this preliminary estimate does not necessarily indicate growth since the 23rd). Yellowish green discoloration extended as much as 38 km to the NE, and brown pumice was floating in lines near the island.

Between 20 December and 20 January, nearly 100 T-phase waves of moderate intensity were received by high-gain seismic stations at Rangiroa, Tuamoto Islands (~9,000 km SE of Fukutoku-Okanoba). J.M. Talandier noted that T-phase waves are characteristic of submarine eruptions, having shallow (ocean) depth. The origin of these waves was in the NW Pacific, and they may be related to the eruption of Fukutoku-Okanoba.

Discolored water has frequently been observed around Fukutoku-Okanoba in recent years. In an interview on a Japan Broadcasting Network newscast, Professor Kosaka of Okayama Univ reported that about 8 years ago a sonar survey from the Tokyo Fisheries Univ ship Seio-maru detected a seamount with a summit 40 m below sea level and roughly 150 m wide, beneath the discolored water zone at Fukutoku-Okanoba. Small islands were formed during the 1904-1905 and 1914 eruptions, but did not persist after 1905 and 1916. An island was reported during an eruption on 24 December 1974, but was not visible the next day.

Information Contacts: JMA; J. Talandier, Laboratoire de Geophysique, Tahiti; NHK Japan Broadcasting Corporation, Tokyo.

02/1986 (SEAN 11:02) New island erodes; floating pumice

The island formed 20 January . . . has been eroded away by wave action since volcanic activity ceased. The island's disappearance was reported by the JMSDF after an hour-long helicopter flight that began 8 March at 0745. The surface of the new edifice was seen under white water, and there was no sign of a volcanic plume.

On 28 January, airplane pilots observed light brown floating pumice within a roughly rectangular NW-SE-trending zone ~200 km long by 50 km wide, extending from ~100 to 300 km SE of the volcano. The pumice was in subparallel teardrop-shaped rafts roughly 4 km wide and 10 km long, elongate perpendicular to the apparent direction of drift.

Rocks collected from Fukutoku-Okanoba after previous eruptions in 1904, 1914, and 1982 were trachyandesites with high alkali contents.

Information Contacts: M. Matson, NOAA/NESDIS; Kyodo Radio, Tokyo; UPI.

03/1986 (SEAN 11:03) January island eroded below sea level

Water discoloration was seen on every overflight in February and March. Wave action gradually eroded the island built by the January eruption, and JMSA personnel reported that it was entirely below sea level by the time of their overflight on 26 March.

Information Contacts: JMA; JMSA.

06/1986 (SEAN 11:06) Discolored sea water

Airplane pilots have observed discolored water at the volcano during all overflights after the temporary island was eroded below sea level in late March. No eruptive activity was reported. The length of the zone of discolored sea water was 0.3 km on 16 April, 2 km on 19 May, and 25 km on 18 June.

Information Contacts: JMA; JMSA.

07/1987 (SEAN 12:07) Submarine eruptions; floating pumice

On 14 July at about 1240, discolored and spouting seawater was reported by observers on a fishing boat. Sprays reached 10 m above the water surface for about a minute at intervals of 10-15 minutes. The next day, 100-150-m-diameter, circular, white-crested waves with spouts in their centers formed at intervals of 6 minutes throughout a 50-minute JMSA overflight. Some floating pumice was found within a zone of yellowish-green seawater that was 500 m wide and stretched 18 km E. No white-crested waves formed after 16 July. During a 17 July overflight, a 30-100 m-wide area of green seawater extended 13 km E. Pumice floated at the E end of this area. On 21 July discolored seawater spread out from two points and minor amounts of pumice were floating in the area. On 30 July deep-green discolored water extended as far as 9 km E over an area 0.5-2 km wide and contained floating brown pumice.

Information Contacts: JMA.

09/1987 (SEAN 12:09) Discolored and spouting seawater

Discolored seawater continued to be seen in August by the JMSA. On 1 August, a zone of yellow-green seawater stretched 3 km NW-SE. The next day water over the vent was discolored green. Discolored water was next reported on 13 August, when cobalt-blue water covered an area of 0.01 x 4 km along an E-W axis. On 17 August the discolored area was 3 km in diameter, and spouting seawater was seen twice. No floating pumice was observed.

Information Contacts: Y. Sawada, JMA; D. Shackelford, Fullerton, CA.

10/1987 (SEAN 12:10) Pale green discolored water

JMSA observed pale green discolored water above the volcano on 17 September.

Information Contacts: Y. Sawada, JMA; D. Shackelford, Fullerton, CA.

10/1988 (SEAN 13:10) Discolored water

JMSA observed sea discolorations on 12 August in an area of 0.09 x 0.9 km and on 15 September in a zone of 0.05 km (N-S) by 1.8 km (E-W).

Information Contacts: Y. Sawada, JMA; D. Shackelford, Fullerton, CA.

07/1989 (SEAN 14:07) Thermal activity discolors sea water

Thermal activity has continued since the January 1986 eruption (11:1-3). A pale green belt of discolored sea water and white bubbles was observed during a JMSA overflight on 9 May 1989. Another monitoring flight, on 14 June, revealed a 50 x 400 m zone near the vent that was discolored cobalt blue.

Information Contacts: JMA; D. Shackelford, Fullerton, CA.

12/1990 (BGVN 15:12) Frequent observations of discolored water

Aerial observations of the ocean surface above the submarine volcano revealed discolored water in January-May, September, and November (table 2). The longest discoloration, 8 km, was observed during an overflight on 17 January. Thermal activity has continued since the January 1986 eruption . . . . Discolored water has been frequently observed since that time (14:07). No discolorations were observed at other submarine volcanoes (Kaitoku, Minami-Hiyoshi, Nikko, and Fukujin seamounts) during 1990.

Table 2. Discolored water at Fukutoku-Okanoba, observed from monthly overflights in 1990. Courtesy of JMSA.

    Date       Water Color        Length of Discoloration

    17 Jan     yellowish brown            8 km
    20 Feb     green                      7 km
    27 Mar     green and brown            1.8 km
    17 Apr     blue                       0.3 km
    16 May     blue                       0.05 km
    June       no discoloration
    Juny       no discoloration
    August     no discoloration
    13 Sep     pale green                 3.6 km
    15 Oct     no discoloration
    20 Nov     yellowish green            0.7 km
    December   no discoloration

Information Contacts: Hydrographic Department, JMSA.

04/1991 (BGVN 16:04) Water discoloration during one of five overflights

A blue water discoloration, extending 2 km E-W, was observed during a 6 February overflight by the JMSA. Overflights on 18 January, 12 March, 15 April, and 10 May revealed no abnormal water.

Information Contacts: JMA.

09/1991 (BGVN 16:09) Water discoloration over submarine vent

A greenish water discoloration was observed during a 30 September overflight by the JMSA. No discoloration was present during a similar overflight on 21 August.

Information Contacts: JMA.

10/1991 (BGVN 16:10) Discolored water

An 18 October overflight by the JMSA revealed discolored green water over the submarine volcano.

Information Contacts: JMA.

10/1992 (BGVN 17:10) Pumice ejected by submarine eruption

A dark plume was observed [in the air above Fukutoku-Okanoba] by fishing crews at about 0800 on 10 November. An overflight by the JMSA from 1315 to 1350 revealed discolored pale-green water in a narrow fan shape to 10 km NNW from the volcano. Brown pumice was seen but no ejections were observed at that time. An overflight on 12 November between 1215 and 1250 revealed that water discoloration was reduced to a zone extending 1 km NW without floating pumice, indicating a decrease in activity. An area of discolored water 2 km long was seen in August but no discoloration was observed during the last overflight before the eruption, on 22 October.

Information Contacts: JMA; JMSA.

11/1992 (BGVN 17:11) Smaller zone of discolored water; no new pumice

Overflights by the JMSA on 12 and 18 November revealed a smaller and weaker area of discolored water over the submarine volcano than on 10 November. The height and size of the dark plume seen by fishermen on 10 November are not known, nor is is known whether the plume contained tephra. Floating pumice was observed that day, but none has been reported since then.

Information Contacts: JMA; JMSA.

12/1993 (BGVN 18:12) Discolored water observed over volcano four times in 1993

Discolored seawater over an area a few hundred meters wide was seen during monthly aerial observations . . . in February, March, June, and September 1993.

Information Contacts: JMA.

12/1995 (BGVN 20:11) Discolored seawater

An aviator flying over the waters of the southern Volcano Islands for Japan's Maritime Safety Agency reported seeing light-green seawater on 25, 27, and 28 November. Discolored seawater was last seen at this location in September 1993.

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

01/1996 (BGVN 21:01) Discolored seawater observed for the second time in three months

On 12, 22, and 23 January, an aviator from the Japan Marine Safety Agency (JMSA) reported distinct discoloration of seawater to yellowish green. Similar discoloration was seen during 25-28 November 1995 (BGVN 20:11/12). Prior to that, discolored seawater was last seen at this location in September 1993.

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

03/1996 (BGVN 21:03) Emission of colored water and long discolored aqueous plumes

Aviators from the Japan Marine Safety Agency (JMSA) began observing yellowish-green discoloration of seawater during 25-28 November 1995 (BGVN 20:11/12). Similar discoloration was seen on 12, 22, and 23 January 1996 (BGVN 21:01), and also on 26 January, as reported by the Japan Meteorological Agency.

Information from the Volcano Research Center revealed that JMSA observers once again noted yellowish brown discolored seawater in the area on 4 April. According to the reports, the colored area expanded like a belt up to ~3 km long. Strong emission of colored water was recognized from two points. Although white-colored suspension was observed on the surface, floating pumices were not recognized. Yellowish-green to yellowish-brown water observed on 12 April formed a plume ~4 km long and 200 m wide, including 3-4 spots from which colored-water was gushing out intermittently. No pumices were recognized.

Information Contacts: Volcanological Division, Seismological and Volcanological Department, Japan Meteorological Agency (JMA), 1-3-4 Ote-machi, Chiyoda-ku, Tokyo 100 Japan; Volcano Research Center, Earthquake Research Institute, University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113, Japan (URL: http://hakone.eri.u-tokyo.ac.jp/vrc/vrc.html); Hydrographic Department, Maritime Safety Agency, 3-1 Tsukiji, 5-Chome, Chuo-ku, Tokyo 104, Japan.

04/1996 (BGVN 21:04) Yellowish-brown discolored seawater seen again

On 4 April, an aviator from the Japan Marine Safety Agency reported discoloration of seawater to yellowish brown at Fukutoku-Okanoba (BGVN 21:03). On 6 and 7 April, similar discoloration was observed by an aviator of the Maritime Defense Force. More discoloration was reported on 12 and 30 April. No floating pumice was observed. Discolored seawater has been seen on a smaller scale at this location, since 24 November 1995 (BGVN 20:11/12).

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

05/1996 (BGVN 21:05) Discolored seawater

During the first half of May, aviators of the Maritime Safety Agency and the Maritime Self-Defense Force reported discoloration of seawater at Fukutoku-Okanoba. Similar discoloration has been observed since November 1995 (BGVN 20:11/12, 21:01, 21:03, and 21:04). An overflight on 23 May indicated no discolored seawater.

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

10/1996 (BGVN 21:10) Water discoloration from submarine volcano observed in September

On 6 September, a Japan Maritime Safety Agency aviator reported yellow-green (in part yellowish brown) discoloration of seawater at Fukutoku-Okanoba over an area of 50 x 150 m, and to light green over a 300 x 500 m area. On 18 September green discoloration was seen by an aviator of the Japan Maritime Self-Defense Force. Smaller areas of discolored seawater have been seen at this location since 24 November 1995 (BGVN 20:11/12, v. 21, nos.1 and 3-5).

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).

01/1997 (BGVN 22:01) Submarine venting continues to discolor seawater

On 12 December, a Japan Maritime Safety Agency aviator reported yellow-green discoloration of seawater at Fukutoku-Okanoba over a 50 x 200 m area. On 27 January, pale green discoloration was seen by an aviator of the Japan Maritime Safety Agency covering an area of 2,000 x 100 m.

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

11/2005 (BGVN 30:11) July 2005 submarine eruption; discolored water and debris

Notice of Fukutoku-Okanoba unrest in 2005 first came to Bulletin editors from Olivier Hyvernaud, information that was amplified by the Japanese Meteorological Agency (JMA) Volcanic Activity Reports of July and October 2005. The JMA reports contain information from the Japanese Marine Defense Forces as well as the Marine Security and Safety Agency and the Tokyo Institute of Technology. In addition, a Japan Coast Guard website (see URL below) contains a more extensive (and yet untranslated) table on recent events at Fukutoku-Okanoba, which includes photos and videos of the July eruption. That table clearly illustrates activity both earlier and later than the 2-3 July eruption, and several other details not discussed here, including the observation of numerous large and steaming blocks floating on the ocean surface at mid-day on 3 July. Bulletin editors hope to decipher this table and include more details in a later report.

The last five Bulletin reports discussing or mentioning Fukutoku-Okanoba appeared in BGVN 22:01, 24:11, 24:12, 25:05, and 28:06 (1997-2003). Note that the last four cases were considered ambiguous and grouped along with reports under the heading "Acoustic signals in 1999-2000 from unknown source, Volcano Islands, Japan" and only the first case was listed under the volcano name). A 3-d view of the volcano and its setting appears as figure 5.

Figure 5. Fukutoku-Okanoba and vicinity shown in a 3-dimensional diagram, with shading (or color) representing various elevation ranges (see key above); vertical exaggeration is considerable but was not stated. The inset contains an index map showing the Volcano islands along the Bonin trench. The diagram represents data from 1999 and views the region from the SE. Fukutoku-Okanoba is a submarine vent ~ 5 km N of the island (Minami-Iwo-jima). Copyrighted image courtesy of the Japan Coast Guard.

JMA reported that at about 1745 on 2 July 2005, a white plume was witnessed at Fukutoku-Okanoba. During an investigation at 1900 that same day, a white plume reached ~ 1 km above the sea surface. A photo taken from considerable distance was included in the JMA report, showing the plume, but the image's limited contrast has led to its exclusion here. In addition to the plume, other evidence for an eruption included debris on the sea surface. When seen on 2 July, the debris covered an area approximately 100 m wide and 300 m long.

JMA noted that 3 July aerial observations suggested that compared to the previous day, eruptive vigor and the height of the white plume had decreased. The key observation then was a zone of discolored seawater (figure 6).

Figure 6. An aerial view of Fukutoku-Okanoba taken on 3 July 2005 as seen from the NE. Debris and discoloration extend from the arrow. Courtesy of the Maritime Security and Safety Agency.

JMA's report of 4 and 5 July aerial investigations noted the lack of a white vapor plume over the sea. In other words, the 2-3 July eruption had calmed, but fresh debris and seawater discoloration were still present. After that, aerial investigations on 15, 17, 20, and 21 July, again disclosed seawater discoloration, but not the presence of floating debris.

The Maritime Security and Safety Agency conducted an underwater topographical survey on 20-22 July 2005, the result of which was the discovery of two craters caused by the recent eruption. The results suggested that the topography just S of those craters was newly raised.

According to a 3 October aerial observer, the ocean surface near Fukutoku-Okanoba, then displayed a pale, blue-white discoloration, interpreted as indicative of volcanism. The area of discoloration extended ~ 300 m in length to the E and was ~ 50 m wide (N-S) at its widest point. However, in the surrounding area they saw no floating debris or plumes containing ash or steam. On 27 October, an aerial observation could not confirm the seawater discoloration.

Satellite data. M. Urai (2005) reported that three days after the 2 July 2005 eruption of Fukutoku-Okanoba, satellite remote sensing using ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) observed the discolored seawater and floating materials within 40 km of the submarine volcano. Some of this abstract follows.

"At the most dense discolored seawater area, reflectance of ASTER band 1 is 3% higher [than] the surrounding seawater. The floating materials are similar in ASTER VNIR [Very Near-Infrared Radiometer] reflectance spectra to clouds, however, the floating materials can be separated from clouds using their shape and stereo image features. The extensions of discolored seawater area and floating material detected by ASTER were 6.34 km2 and 1.14 km2, respectively. It is possible to estimate the scale of [a] submarine eruption using the quantitative data derived from satellite remote sensing."

Distant hydrophones. Robert Dziak and Haru Matsumoto monitor N Pacific volcano seismicity with the National Oceanic and Atmospheric Agency/Pacific Marine Environmental Laboratory (NOAA/PMEL). They initially learned of the eruption via the internet. Regarding the 2 July eruption, Dziak wrote to the Bulletin staff on 22 November 2005. Some of his messages follow.

". . . the [N] Pacific hydrophone array we use recorded seismicity during the Fukutoku-Okanoba eruption near Iwo Jima. I was aware of the eruption at the time [mid 2005] thanks to Haru [Matsumoto; he designed and built the instruments used there to record the T-wave events] forwarding a news image of the discolored water. Despite being only able to roughly locate the seismicity since it is way west of our array, I am pretty sure Fukutoku-Okanoba was the source because the arrival azimuths and timing of the signals were a match. The last earthquake activity we recorded from this area occurred on 25 September [2005] . . .. A few years ago I was contacting you [Smithsonian Institution] about our recording of harmonic tremor from a source in the Volcano Islands. The conclusion I published in JGR [Dziak and Fox, 2002] was that either Fukutoku-Okanoba or Funka-asane ([N] of Iwo Jima) was the probable source because of a history of submarine volcanic activity at both volcanoes. We have still been recording this tremor intermittently over the last few years and another pulse of it occurred during the Fukutoku-Okanoba eruption on July 2, 2005. The last occurrence was on August 22.

According to an Email from Dziak on 23 November 2005, "...I think the tremor is coming from [Fukutoku-Okanoba or Funka-asane]. I was only able to get synchronous data from the French Polynesian seismic net (Hyvernaud). They confirmed the signals but it did not help much with location because they were so far away. My thought is the source of earthquakes and tremor from these submarine volcanoes is at an ocean depth within the sound channel. This allows for very efficient seismic-acoustic coupling and acoustic propagation throughout the Pacific ocean basin."

References. Dziak, R.P., and Fox, C.G., 2002, Evidence of harmonic tremor from a submarine volcano detected across the Pacific Ocean basin: Journal of Geophysical Research, v. 107(B5), p. 2085; doi 10.1029/2001JB0001772085.

Kato, Y., 1988, Gray pumices drifted from Fukutoku-oka-no-ba to the Ryukyu Islands: Bulletin of the Volcanological Society of Japan, Second Series, v. 33, p. 21-30.

Ossaka, J., Mitsuno, C., Shibata, T., Matsuda, T., Hirabayashi, J., Tsuchide, M., Sakurai, M., and Sato, H., 1986, The 1986 submarine eruption of Fukutoku-okanoba, Part 2. Volcanic ejectas: Bull. Vol. Soc. Japan, v. 31, p. 134-135.

Urai, M., 2005, Monitoring submarine volcano with satellite remote sensing: Eos Trans, AGU, v. 86(52), Fall Meet. Suppl., Abstract 611A-1176.

Information Contacts: Olivier Hyvernaud, Laboratoire de Géophysique, BP 640 Pamatai, Tahiti, French Polynesia (Email: hyvernaud@labogeo.pf); Japanese Meteorological Agency, (URL: http://www.jma.go.jp/JMA_HP/jma/indexe.html); Robert Dziak and Haru Matsumoto, NOAA PMEL, Hatfield Marine Science Center, 2115 SE Oregon State University Drive, Newport, OR 97365, USA (Email: Robert.p.dziak@noaa.gov; Haru.Matsumoto@noaa.gov); Yukio Hayakawa (Email: hayakawa@vulcania.jp); Daily Yomiuri News (URL: http://www.yomiuri.co.jp/dy/national/20050704TDY01003.htm); Reuters; Associated Press; Tokyo Institute of Technology, 2-12-1 O-Okayama, Meguro-ku, Tokyo 152-8551, Japan; Japan Coast Guard, Hydrographic and Oceanographic Department (URL: http://www1.kaiho.mlit.go.jp/GIJUTSUKOKUSAI/kaiikiDB/kaiyo24-2.htm); Japan Maritime Security and Safety Agency, Oceanic Information Section (URL: http://www1.kaiho.mlit.go.jp/).

01/2007 (BGVN 32:01) Discolored water attributed to submarine volcanism

Oliver Hyvernaud twice notified the Bulletin of Notice to Mariners reports of discolored sea water observed on 4 October and 15 November 2006 at about 24°17'N, 141°29'E. Both warnings referred to the same general location, encompassing an area of ocean 93 km SSW of Iwo Jima. In reality, the two positions noted below are ~ 1.3 km apart, perhaps overlapping each other. The warnings were as follows:

1) Discolored water with submarine volcanic activity reported within 1,700 m of 24°17.5' N, 141°29.4 E at 0400 UTC on 4 October 2006 [ref. Notice to Mariners, 14 October 2006 (no. 41), HYDROPAC Warning 1921/06(97) North Pacific, issued 1009 UTC on 4 October 2006].

2) Discolored water with submarine volcanic activity reported within 2,000 m of 24°17.1' N, 141°28.8 E at 0236 UTC on 15 November 2006 [ref. Notice to Mariners, 2 December 2006 (no. 48), HYDROPAC Warning 2225/06(97) North Pacific, issued 1133 UTC on 16 November 2006]

For the locations given for warnings 1 and 2, the respective deviations from coincidence with Fukutoku-Okanoba (at the coordinates given above) are 1.4 and 0.8 km. That seamount frequently produces discolored seawater and is known to erupt on occasions as well, and is thus the probable source for the discolored water.

According to the Japan Meteorological Agency, observations on 15 November 2006 by the Japan Maritime Self Defense Force and aerial observations on 21 November 2006 by the Japan Coast Guard revealed areas of discolored water on the sea surface above the volcano. Those cases seemed to be caused by volcanic activities.

Information Contacts: Olivier Hyvernaud, Laboratoire de Géophysique, BP 640 Pamatai, Tahiti, French Polynesia (Email: hyvernaud@labogeo.pf); Notice to Mariners, National Geospatial-Intelligence Agency, National Ocean Service, and U.S. Coast Guard, Office of Corporate Relations, Public Affairs Division, MS D-54, 4600 Sangamore Road, Bethesda, MD 20816-5003, USA (URL: http://www.nga.mil/portal/site/maritime/); Japan Meteorological Agency, 1-3-4 Otemachi, Chiyoda-ku, Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/jma/indexe.html).

02/2010 (BGVN 35:02) Airborne ash and cloudy water during 3 February 2010 eruption

The submarine volcano Fukutoku-Okanoba, frequently the source of discolored water (e.g., BGVN 32:01 and 30:11), erupted on the morning of 3 February 2010, sending a plume of ash and steam 100 m into the air (figure 7) and turning the surrounding ocean a yellow-green color (figure 8). Additional observations of discolored water have been frequently documented in JMA reports since November 2006 (BGVN 32:01). More details of that activity, from January 2007 through December 2009, will be provided in a following Bulletin.

Figure 7. Aerial photograph of an ash plume rising from the ocean over Fukutoku-Okanoba on 3 February 2010. Photograph courtesy Japan Coast Guard.
Figure 8. During a lull in the 3 February 2010 eruption of Fukutoku-Okanoba, some water above the summit bubbled and took on yellowish-green colors. Aerial photograph courtesy Japan Coast Guard.

The February 2010 eruption was discovered at about 0745 by the Japan Coast Guard patrol boat Yashima on a routine survey. The crew first noticed "smoke" coming from the surface of the ocean ~ 5 km NNE of the island of Minami-Iwo-jima. The crew also heard a blast and felt its pressure wave. The Yashima continued to monitor the site from a safe distance.

Satellite imagery provided evidence that the activity persisted for at least several days. On 9 February the underwater plume appears as a complex shape N of the volcano (figure 9). Two days later, on 11 February, the plume was spread W of the volcano (figure 10).

Figure 9. On 9 February 2010, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite captured this false-color image of the ocean around Fukutoku-Okanoba volcano. Water colored by the underwater plume appears lighter in contrast to the surrounding water. The discolored water initially formed a rough V-shape N of the summit. Courtesy of NASA Earth Observatory.
Figure 10. Satellite image taken 11 February 2010 of the ocean around Fukutoku-Okanoba volcano. The water colored by the plume forms a V-shape W of the volcano summit. This true-color image (enhanced for publication) was taken by the Advanced Land Imager (ALI) on NASA's EO-1 satellite. Courtesy of NASA Earth Observatory.

JMA isssued eruption alerts for 9 March and 8 April 2010. This suggests that the eruption continued into April.

Information Contacts: Japan Meteorological Agency, 1-3-4 Otemachi, Chiyoda-ku, Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/jma/indexe.html); NASA Earth Observatory (URL: http://earthobservatory.nasa.gov/).

Fukutoku-Oka-no-ba is a submarine volcano located 5 km NE of the pyramidal island of Minami-Ioto. Water discoloration is frequently observed from the volcano, and several ephemeral islands have formed in the 20th century. The first of these formed Shin-Ioto ("New Sulfur Island") in 1904, and the most recent island was formed in 1986. The volcano is part of an elongated edifice with two major topographic highs trending NNW-SSE, and is a trachyandesitic volcano geochemically similar to Ioto.

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

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
2010 Feb 3 2010 Apr 8 (?) Confirmed 1 Historical Observations
[ 2005 Sep 11 ] [ 2007 Feb (in or after) ] Uncertain 0  
2005 Jul 2 2005 Jul 21 (?) Confirmed 1 Historical Observations
[ 2002 Dec 19 ] [ 2003 Mar 11 ] Uncertain 0  
[ 2001 Oct 30 ] [ 2002 Jun 19 ] Uncertain 0  
[ 2000 Jul 26 ] [ 2001 Jun 13 ] Uncertain 0  
[ 1999 Sep 8 ] [ 2000 Feb 18 ] Uncertain 0  
[ 1998 Oct 16 ] [ 1999 Jan 12 ] Uncertain 0  
[ 1997 Nov 18 ] [ 1998 May 21 ] Uncertain 0  
[ 1995 Nov 21 ] [ 1997 Jul 28 ] Uncertain 0  
[ 1994 Jul 28 ] [ 1994 Jul 28 ] Uncertain 0  
1992 Nov 10 1993 Sep 9 (?) Confirmed 1 Historical Observations
[ 1991 Jul 19 ] [ 1991 Oct 18 ] Uncertain 0  
[ 1987 Sep 4 ] [ 1991 Feb 6 ] Uncertain 0  
1987 Jul 14 1987 Aug 30 (?) Confirmed 0 Historical Observations
[ 1986 Apr 7 ] [ 1987 Jun 26 ] Uncertain 0  
1986 Jan 18 1986 Mar 28 (?) Confirmed 2 Historical Observations
[ 1976 Aug 2 ] [ 1985 Dec 23 ] Uncertain 0  
1974 Dec 24 1975 Nov 13 (?) Confirmed 2 Historical Observations
1973 Dec 18 1974 Feb 16 Confirmed 2 Historical Observations 3.8 km NNE of Minami-Iwo-jima
[ 1972 Oct 1 ] [ 1972 Oct 1 ] Uncertain 0  
[ 1968 Aug 14 ] [ 1968 Aug 20 ] Uncertain 0  
[ 1968 Feb 9 ] [ 1968 Feb 9 ] Uncertain 0  
[ 1967 Jul 1 ] [ 1967 Jul 1 ] Uncertain 0  
[ 1963 Oct 27 ] [ Unknown ] Uncertain 0  
[ 1962 Jul 1 ] [ 1962 Oct 1 ] Uncertain 0  
[ 1960 Jul 1 ] [ 1960 Sep 1 ] Uncertain 0  
[ 1959 Jul 1 ] [ 1959 Oct 1 ] Uncertain 0  
[ 1958 Jul 1 ] [ 1958 Oct 1 ] Uncertain 0  
[ 1956 Apr 1 ] [ 1956 May 1 ] Uncertain 0  
[ 1955 Apr 1 ] [ 1955 Apr 1 ] Uncertain 0  
[ 1954 Feb 4 ± 4 days ] [ Unknown ] Uncertain 0  
[ 1953 Dec 1 ] [ 1953 Dec 1 ] Uncertain 0  
[ 1952 Jun 20 ] [ 1952 Jun 20 ] Uncertain 0  
[ 1950 Feb 1 ] [ 1950 Feb 1 ] Uncertain 0  
1914 Jan 13 1914 Aug 21 (in or after) Confirmed 3 Historical Observations Shin-Iwo-jima
1904 Nov 14 1905 May 16 (?) Confirmed 3 Historical Observations Shin-Iwo-jima

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

Shin-Iwo-jima | Sin-Io-jima | Shin-Io-jima | Minami-Iwo-jima | Hukutoku-okanoba | Sin-Iwo-zima | Fukutoku-Okanoba
A 3-4 km eruption column above Fukutoku-Okanoba was seen from fishing boats on Janaury 18, 1986. A 4-km plume was detected by radar on the following day. On January 20 a new island was formed (seen here to the right of the eruption plume). The island reached maximum dimensions of 600 x 400 m, with a height of 15 m. Frequent strong explosions continued on January 21, the day of this photo, and decreased in intensity that afternoon. Explosive activity ended by the next morning, and the island had disappeared by March 8.

Photo by G. Iwashita, 1986 (Japan Meteorological Agency).
A new island at the Fukutoku-Okanoba submarine volcano is seen on January 28, 1986. It was first seen on January 20, four days after fishing boats first observed an eruption plume rising from the sea. The island reached a maximum size of 600 x 400 m, with a height of 15 m. By January 22, explosive activity had ceased, and the island was completely eroded away by the sea by March 8.

Photo by G. Iwashita, 1986 (Japan Meteorological Agency).
Fukutoku-Okanoba, seen here in eruption in 1986, is a submarine volcano located 5 km NE of the pyramidal island of Minami-Iwo-jima (right). Water discoloration is frequently observed near the volcano, and several ephemeral islands have formed in the 20th century. The first of these formed Shin-Iwo-jima in 1904, and the most recent island is seen in this January 21, 1986 photo. Wave erosion removed the island by March 8. Fukutoku-Okanoba is part of an elongated edifice with two major topographic highs trending NNW-SSE.

Photo by G. Iwashita, 1986 (Japan Meteorological Agency).
The orange-colored topographic high at the top of this bathymetric image is Kita-Fukutokutai submarine volcano. This newly recognized submarine volcano lies halfway between Iwo-jima and Minami-Iwo-jima islands, NW of Fukutoku-Okanoba submarine volcano (center; north of Minami-Iwo-jima). Water discoloration was reported several times beginning in 1937 at Kita-Fukutokutai volcano. In 1988 a fishing boat reported an eruption column about 100 m high, although the report was not confirmed at the time.

Image courtesy of HOD Japan Coast Guard (http://www1.kaiho.mlit.go.jp/jhd-E).
An aerial view of Fukutoku-Okanoba taken on July 3, 2005 as seen from the NE shows a plume of debris and discoloration extending from the arrow. On the previous day a white plume was observed at Fukutoku-Okanoba, which later was observed to have reached ~ 1 km above the sea surface. Numerous large and steaming blocks were seen floating on the ocean surface at mid-day on July 3. The pyramidal island in the background is Shin-Iwo-jima.

Photo courtesy of Japan Maritime Security and Safety Agency, 2005.

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/.

Sun C-H, Stern R J, 2001. Genesis of Mariana shoshonites: contribution of the subduction component. J Geophys Res, 106: 589-608.

Volcanological Society of Japan, 1960-96. Bull Volc Eruptions, no 1-33. [Annual reports issued 1 to 3 years after event year, published since 1986 in Bull Volc].

Yuasa M, Murakami F, Saito E, Watanabe K, 1991. Submarine topography of seamounts on the volcanic front of the Izu-Ogasawara (Bonin) Arc. Bull Geol Surv Japan, 42: 703-743.

Volcano Types

Submarine
Pyroclastic cone

Tectonic Setting

Subduction zone
Crustal thickness unknown

Rock Types

Major
Trachyandesite / Basaltic trachy-andesite

Population

Within 5 km
Within 10 km
Within 30 km
Within 100 km
11
19
19
951

Affiliated Databases

Large Eruptions of Fukutoku-Oka-no-Ba 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.