Supply Reef

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  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 20.13°N
  • 145.1°E

  • -8 m
    -26 ft

  • 284142
  • Latitude
  • Longitude

  • Summit

  • Volcano

The Global Volcanism Program has no activity reports for Supply Reef.

The Global Volcanism Program has no Weekly Reports available for Supply Reef.

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.

05/1969 (CSLP 43-69) Submarine eruption during 11-12 March

09/1985 (SEAN 10:09) Discolored water but no eruption plume

11/1985 (SEAN 10:11) T-Phases recorded in Tahiti may be from this site

10/1989 (SEAN 14:10) Twenty-one hours of volcanic seismicity

12/1989 (SEAN 14:12) Renewed activity at September site

Contents of Monthly Reports

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

All times are local (= UTC + 10 hours)

05/1969 (CSLP 43-69) Submarine eruption during 11-12 March

Card 0528 (06 May 1969) Acoustic activity during 11-12 March

The following was received in a telephone report from Tom Simkin (Smithsonian Institution). "Examination of government recordings made at Eniwetok, Wake, and Midway hydrophone stations turned up acoustic activity which appears to be at the location of the March 1967 event (Norris and Johnson, 1969) near Farallon de Parajos in the Northern Mariana Islands [but see next report for better location placing this event just NW of Supply Reef]. The recent activity occurred at a fairly uniform rate for two days beginning 11 March 0100 GMT and ending 12 March 2300 GMT, 1969."

Reference. Norris, R.A., and Johnson, R.H., 1969, Submarine volcanic eruptions recently located in the Pacific by Sofar hydrophones: Journal of Geophysical Research, v. 74, no. 2, p. 650-664.

Card 0534 (08 May 1969) Explosions sounds and water discoloration

The following cable was received from the Japanese Meteorological Agency. "Fishing boat sailing near Uracas Island in Marianas informed of submarine eruption as follows: From about 0930 GMT on 12 March explosion sounds - three times - were heard in latitude 20.24°N, longitude 145.02°E, neighboring sea surface was colored in brown."

Information Contacts:
Card 0528 (06 May 1969) Roger A. Norris, The T-Phase Project, University of Hawaii, Honolulu, Hawaii.
Card 0534 (08 May 1969) Seismological Section, Japanese Meteorological Agency.

09/1985 (SEAN 10:09) Discolored water but no eruption plume

On 2 September, a Continental Air Micronesia pilot observed a zone of brown and light green discolored water about 3 km in diameter, centered about 30 km S of Farallon de Pajaros. No eruption plume was seen by the pilot and inspection of satellite images for several days after 2 September revealed no visible plumes. Cloudy weather obscured the area in the days immediately preceding 2 September. No other reports of activity have been received.

The location of the 1985 activity is approximate, but is not inconsistent with the position of the 1969 eruption and the seamount.

Information Contacts: N. Banks, CVO, Vancouver, WA; W. Gould, NOAA/NESDIS.

11/1985 (SEAN 10:11) T-Phases recorded in Tahiti may be from this site

Between 2 August and 5 September, 109 T-phase events originating in the NW Pacific were received by a high-gain station at Rangiroa, Tahiti. J.M. Talandier notes that their characteristics are typical of submarine volcanic eruptions, being of shallow (ocean) depth; the timing of the events coincides with the presence of a zone of discolored water near [Supply Reef]. However, a precise origin cannot be determined because the events were of weak amplitude and recorded by only one station.

Information Contact: J. Talandier, Lab. de Geophysique, Tahiti.

10/1989 (SEAN 14:10) Twenty-one hours of volcanic seismicity

An intense episode of apparent submarine volcanism was recorded 21-22 September by an 11-channel hydrophone array on Wake Island, an ocean bottom seismometer off Japan's Boso Peninsula, and the Polynesian Seismic Network's Pomariorio station, on Rangiroa atoll. Strong activity began at about 1100 and peaked between 1230 and 1520, with several hundred distinct events detected before the episode ended abruptly at about 0755 the next morning. During the activity, continuous noise levels in the SOFAR channel remained at least 20 dB above normal ambient values, at frequencies of 5-30 Hz. T-Phase arrivals at the three sites were used to determine a rough location for the activity at 21.9°N, 145.9°E, with a typical potential error of about ± 100 km [but see 14:12]. However, the calculated position is displaced >200 km E of the northern Marianas volcanic arc, falling on the W edge of the trench.

The nearest known submarine volcanic site is . . . Farallon de Pajaros (Uracas) at 20.53°N, 144.90°E. Activity was last reported from the area on 2 September 1985, when a 3-km zone of discolored water near the 1969 eruption site (about 30 km S of Farallon de Pajaros) was observed from an aircraft. Between 2 August and 5 September 1985, the Polynesian Seismic Network's Rangiroa station recorded 109 T-Phase events, with characteristics typical of submarine eruptions, originating from the NW Pacific. However, no other seismic stations were known to have recorded the activity and a precise location was impossible.

Reference. McCreery, C., Oliveria, F., and Walker, D., 1989, Submarine volcano: EOS, v. 70, p. 1466.

Information Contacts: D. Walker, Univ of Hawaii; J. Talandier, LDG, Tahiti; Y. Sawada, JMA.

12/1989 (SEAN 14:12) Renewed activity at September site

An ocean bottom seismometer off the Boso Peninsula, Japan, and hydrophones on Wake Island detected renewed episodes of apparent submarine volcanism on 22-24 and 26-27 December. Arrival directions and times were very similar to those from the 21-22 September activity, and probably originated from the same area.

Seismicity began to be recorded by the Boso Peninsula instrument on 22 December at about 0630, and events soon became frequent, although intervals between events were slightly longer than in September. Seismicity had nearly ended shortly before 0200 on 24 December, although one additional shock was recorded at 0245. T-phase signals resumed on 26 December at about 1600 and continued until about 2300 the next day, but occurred at significantly longer intervals than the two earlier episodes.

Using more precise sound velocities, Univ of Hawaii geophysicists refined the locations of the 21-22 September events to about 20.3°N, 144.9°E, roughly 30 km S of . . . Farallon de Pajaros (Uracas). The potential location error remains large, but is oriented along a NE-SW line oblique to the volcanic chain. The 21-22 September locations are very close to the site of the most recent documented activity near Farallon de Pajaros, a 3-km zone of discolored water that was observed in September 1985 near the 1969 eruption site.

Information Contacts: Y. Sawada, JMA; C. McCreery and D. Walker, Univ of Hawaii.

Supply Reef is a conical submarine volcano in the northern Mariana Islands that rises to within 8 m of the surface. The andesitic seamount lies about 10 km NW of the Maug Islands, the emergent summit of a submarine volcano that is joined to Supply Reef by a low saddle at a depth of about 1800 m. Supply Reef was mapped as Quaternary; living corals on the crater rim suggest that it is either dormant or extinct (Corwin, 1971). Several submarine eruptions have been detected by sonar signals originating from points very approximately located at distances of 15-25 km NW.

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

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
1989 Sep 21 1989 Dec 27 Confirmed 0 Unknown Volcano Uncertain: NW of Supply Reef (~20.3 N, 144.9E)
[ 1985 Sep 2 ] [ Unknown ] Uncertain 0   25 km? NW of Supply Reef
1969 Mar 11 1969 Mar 13 Confirmed 0 Hydrophonic NW of Supply Reef (20.24 N, 145.02 E)

The Global Volcanism Program has no synonyms or subfeatures listed for Supply Reef.

The Global Volcanism Program has no photographs available for Supply Reef.

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.

Bloomer S H, Stern R J, Smoot N C, 1989. Physical volcanology of the submarine Mariana and Volcano arcs. Bull Volc, 51: 210-224.

Corwin G, 1971. Quaternary volcanics of the Mariana Islands. Unpublished manuscript, 137 p.

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

Volcano Types


Tectonic Setting

Subduction zone
Crustal thickness unknown

Rock Types

Andesite / Basaltic Andesite


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

Affiliated Databases

Large Eruptions of Supply Reef 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.