Volcano Information

    Agrigan
    Volcanic Alert Level: UNASSIGNED Aviation Color Code: UNASSIGNED

    • Current Update, last updated Jul 18, 2007 11:20 MPT:
      An earthquake was reported felt on Agrigan island at 3:49 pm July 16 local time. About 3 seconds of shaking was reported by a local resident. Seismometers on Sarigan and Anatahan recorded the earthquake and allowed estimation the magnitude at approximately 3.3. No sulfur smell or any other signs of volcanic activity were reported on July 16 or in a followup call on July 17.
    • Volcanic History Overview: The highest of the Marianas arc volcanoes, Agrigan contains a 500-m-deep, flat-floored caldera. The elliptical island is 8 km long; its 965-m-high summit is the top of a massive 4000-m-high submarine volcano, the second largest in the Marianas Islands. Deep radial valley dissect the flanks of the thickly vegetated stratovolcano. The elongated caldera is 1 x 2 km wide and is breached to the NW, from where a prominent lava flow extends to the coast and forms a lava delta. The caldera floor is surfaced by fresh-looking lava flows and also contains two cones that may have formed during the volcano's only historical eruption in 1917. This eruption deposited large blocks and 3 m of ash and lapilli on a village on the SE coast, prompting its evacuation. (from the Smithsonian Global Volcanism Program)
    • Location: Mariana Islands, Mariana Islands

      Latitude: 18.77
      Longitude: 145.67
      Elevation: 965 m

      Recent Eruption: 1917
    • 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