Volcano Information

    Anatahan
    Volcanic Alert Level: ADVISORY Aviation Color Code: YELLOW

    • Current Update, last updated Aug 22, 2008 09:08 MPT:
      Report prepared by the U.S. Geological Survey.

      Seismicity remains low though occasional low-amplitude tremor bursts lasting minutes occasionally occur. No plumes have been reported.

      On Aug. 20 there were a few low-amplitude tremor bursts lasting ~2 minutes.

      On Aug. 21 there were two episodes of volcanic tremor - ~5 minutes of tremor starting at 16:15 UTC and ~50 minutes of tremor starting at 16:50 UTC. Subsequent seismicity returned to background levels.

      During times of northerly winds, the Anatahan plume, if present, could be directed towards the CNMI and Guam. If this happens, residents may notice hazy air conditions and smell sulfur. The Emergency Management Office (EMO) of the CNMI government will issue volcanic haze and sulfur advisories if appropriate.

      Access to the island may be restricted by the CNMI government. Contact the EMO to get the latest information.

      USGS contact information: duty scientist (808) 967-8815 http://volcano.wr.usgs.gov/cnmistatus.php


    • Volcanic History Overview: The elongate, 9-km-long island of Anatahan in the central Mariana Islands consists of large stratovolcano with a 2.3 x 5 km, E-W-trending compound summit caldera. The larger western portion of the caldera is 2.3 x 3 km wide, and its western rim forms the island's 790-m high point. Ponded lava flows overlain by pyroclastic deposits fill the floor of the western caldera, whose SW side is cut by a fresh-looking smaller crater. The 2-km-wide eastern portion of the caldera contained a steep-walled inner crater whose floor prior to the 2003 eruption was only 68 m above sea level. A submarine volcano, NE Anatahan, rises to within 460 m of the sea surface on the NE flank of the volcano, and numerous other submarine vents are found on the NE-to-SE flanks. Sparseness of vegetation on the most recent lava flows on Anatahan had indicated that they were of Holocene age, but the first historical eruption of Anatahan did not occur until May 2003, when a large explosive eruption took place forming a new crater inside the eastern caldera. From the Smithsonian Global Volcanism Program.
    • Location: Mariana Islands, Mariana Islands

      Latitude: 16.35
      Longitude: 145.67
      Elevation: 790 m

      Recent Eruption: 2005
    • Hazard Assessments: Sako, M. K.; Trusdell, F. A.; Koyanagi, R. Y.; Kojima, George; Moore, R. B., 1995, Volcanic investigations in the Commonwealth of the Northern Mariana Islands, April to May 1994, USGS Open-File Report 94-705.
    • Link to monitoring data: NMI Web Site