Mehetia

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  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 17.87°S
  • 148.07°W

  • 435 m
    1427 ft

  • 333040
  • Latitude
  • Longitude

  • Summit
    Elevation

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    Number

Most Recent Bulletin Report: March 1982 (SEAN 07:03)


Seismic activity stops

Seismic activity that began in March 1981 ceased in December. Only a few low-energy events per month have been recorded since. Bathymetric reconnaissance around the island found evidence of an elliptical opening at 1,700 m below sea level on the SE flank, in the same location as the initial events of the earthquake swarm. RSP scientists interpreted the opening as a possible crater and the activity as a magmatic intrusion or eruption.

Information Contacts: J.M. Talandier, Lab. de Géophysique, Tahiti.

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

Index of Bulletin Reports


Reports are organized chronologically and indexed below by Month/Year (Publication Volume:Number), and include a one-line summary. Click on the index link or scroll down to read the reports.

10/1981 (SEAN 06:10) Several months of increased seismicity

03/1982 (SEAN 07:03) Seismic activity stops




Bulletin Reports

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


10/1981 (SEAN 06:10) Several months of increased seismicity

A swarm of earthquakes centered beneath Mehetia began suddenly on 6 March and was continuing in late October. After the first two days of the swarm, characterized by numerous weak events, seismographs began to record occasional larger shocks (figure 1). The seismic energy released during the first week of the swarm greatly exceeded the previous total energy release detected by the Tahitian seismic net since the first stations were installed in 1962-63. Both the number of earthquakes (figure 2) and energy release (figure 3) varied considerably, with periods of increased activity separated by brief lulls. Epicenters were about 10 km SE of the crater. There were several groups of foci, which may indicate vertical migration, but it was impossible to compute depths of focus for most of the events. A temporary seismic station operated on Mehetia 25-30 March recorded local earthquakes at about 13 km depth.

Figure 1. Log plot of number of events vs. magnitude at intervals of ML 0.2 recorded from Mehetia, 6 March-15 December 1981. The b value (slope) of the regression line is 1.13 ± 0.03 for the entire swarm. For the first two days of the swarm, characterized by numerous weak events, b = 1.63. Courtesy of J. Talandier.
Figure 2. Number of recorded earthquakes (ML 0.9 or greater) per day (3-day means) at Mehetia, 6 March-early December 1981 (293 days). The total number of such events during this interval was 3,536. The Tahitian seismic net records most local events of ML 1.1 or greater, but fluctuating levels of microseismic noise prevent consistent recording of weaker events. Courtesy of J. Talandier.
Figure 3. Seismic energy released by the Mehetia swarm (3-day intervals), 6 March-early December 1981. Courtesy of J. Talandier.

By late October, more than 3,000 local events of magnitude 0.9 (ML) or stronger had been recorded. Of these, about 30 were stronger than ML 3.0, including magnitude 4.0 and 4.3 shocks. Because of the detection limits (usually about ML 1.1, but weaker seismicity is sometimes recorded during periods of lesser microseismic noise) for events in the Mehetia area (~140 km from the nearest Tahitian net station), harmonic tremor, if any, would probably not be recorded. Talandier's extrapolation of the well-defined frequency-magnitude relationship indicates that about 50,000 events stronger than ML 0.1 have probably occurred during the swarm. Talandier also notes that the Mehetia swarm and seismicity associated with Hawaiian volcanoes showed similarities in number and magnitude of events and seismogram characteristics, as well as the detection of long-period waves that could be generated by events occurring beneath a magma chamber. No surface volcanic activity has been reported at Mehetia. The island is uninhabited, working conditions there are difficult, and no geologist has visited the area recently.

Mehetia is a well-defined cone about 1,500 m in diameter and 435 m high, with a 200-m-diameter crater at the summit. No historic eruptions have been reported, but the limited erosion of the crater and flanks, lack of vegetation at the summit, and Tahitian legends of "big fires" all indicate that eruptions probably took place less than 2,000 years ago.

Information Contacts: J.M. Talandier, Lab. de Géophysique, Tahiti.
Download or Cite this Report

03/1982 (SEAN 07:03) Seismic activity stops

Seismic activity that began in March 1981 ceased in December. Only a few low-energy events per month have been recorded since. Bathymetric reconnaissance around the island found evidence of an elliptical opening at 1,700 m below sea level on the SE flank, in the same location as the initial events of the earthquake swarm. RSP scientists interpreted the opening as a possible crater and the activity as a magmatic intrusion or eruption.

Information Contacts: J.M. Talandier, Lab. de Géophysique, Tahiti.
Download or Cite this Report

The 1.5-km-wide, steep-sided island of Mehetia, the youngest and SE-most of the Society Islands, lacks a well-developed fringing coral reef. The 435-m-high island (known as Meetia or Meketia in the Tahitian and Tuamotuan languages, respectively) is the summit of a large volcano that rises 4000 m from the sea floor. An older edifice is formed of a lava flow sequence overlain by hydromagmatic deposits and strombolian ejecta. A well-preserved Holocene crater, 150 m wide and 80 m deep, is located NW of the summit and has been the source of the youngest lava flows on the island (Binard et al., 1993). Polynesian legends mention "large fires," and the lack of vegetation on some lava flows suggests that the latest activity occurred within the last 2000 years (Talandier and Custer, 1976). Other recent activity at Tehetia originated from a submarine crater at 2500-2700 m depth on the SE flank.

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

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
[ 1981 Mar 5 ] [ 1981 Dec ] Uncertain 0   SE of Mehetia (-1700 m?)

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

Meetia | Meketia
The 1.5-km-wide, steep-sided island of Mehetia, seen here from the south, is the youngest and SE-most of the Society Islands. The 435-m-high island is the summit of a large volcano that rises 4000 m from the sea floor. Wave erosion has truncated lava flows of an older edifice, leaving steep cliffs that overlie coral reefs seen at the peninsula in the left foreground. The summit of the island is fomed by a younger edifice that may have been the source of apparent eruptive events mentioned in Polynesian legends.

Photo by Jacky Vedraine (http://www.polynesiepassion.net).

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.

Binard N, Maury R C, Guille G, Talandier J, Gillot P Y, Cotten J, 1993. Mehetia Island, South Pacific: geology and petrology of the emerged part of the Society hot spot. J Volc Geotherm Res, 55: 239-260.

Cheng Q C, Macdougall J D, Lugmair G W, 1993. Geochemical studies of Tahiti, Teahitia and Mehetia, Society Island Chain. J Volc Geotherm Res, 55: 155-184.

Duncan R A, McDougall I, 1976. Linear volcanism in French Polynesia. J Volc Geotherm Res, 1: 197-227.

Hekinian R, Bideau D, Stoffers P, Cheminee J L, Muhe R, Puteanus D, Binard N, 1991. Submarine intraplate volcanism in the South Pacific: geological setting and petrology of the Society and Austral regions. J Geophys Res, 96: 2109-2138.

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

Talandier J, 1983. Activite volcanosismique de la region de Tahiti-Mehetia (Pacifique Central Sud) Crise Du Teahitia En Mars Et Avril. Laboratoire Geophysique Tahiti, unpublished ms, 82 p.

Talandier J, Kuster G T, 1976. Seismicity and submarine volcanic activity in French Polynesia. J Geophys Res, 81: 936-948.

Talandier J, Okal E A, 1984a. The volcanoseismic swarms of 1981-1983 in the Tahiti-Mehetia area, French Polynesia. J Geophys Res, 89: 11,216-11,234.

Volcano Types

Stratovolcano
Pyroclastic cone(s)

Tectonic Setting

Intraplate
Oceanic crust (< 15 km)

Rock Types

Major
Trachybasalt / Tephrite Basanite
Basalt / Picro-Basalt
Minor
Phono-tephrite / Tephri-phonolite

Population

Within 5 km
Within 10 km
Within 30 km
Within 100 km
114
114
114
114

Affiliated Databases

Large Eruptions of Mehetia 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.