Volcano Information

    Mauna Loa
    Volcanic Alert Level: ADVISORY Aviation Color Code: YELLOW

    • Current Update, last updated Apr 27, 2009 17:50 HST:
      Mauna Loa is not erupting. Slow extension, as measured by GPS receivers on opposite sides of the volcano, continued. Line lengths have been increasing at a slightly faster rate since September, 2008, due mostly to slippage on basalt faults beneath Mauna Loa's east flank and not to an increase in magma supply to the volcano. Recent instrumental problems with a summit GPS receiver have produced more-than-usual data scatter - this problem will be corrected when weather permits.

      Tiltmeters have recorded no significant changes other than abrupt offsets that are related to instrumental issues or significant earthquakes. Diurnal tilt, or the tilting due to daily heating and cooling of the ground, was diminished by snowfall starting Christmas Eve, 2008.

      Sensors within a crack in Moku`aweoweo crater floor continued to record background gas concentrations; fumarole temperatures also remained steady except for a few several-hour-long periods of temperature decrease due to snowfall.

      Since the beginning of January, 2005, HVO analysts have rarely located more than 10 earthquakes per week beneath Mauna Loa summit. Each week, 1-5 earthquakes are also located beneath the Kealakekua area of west Mauna Loa. These levels are typical of the past several years. The Kao`iki seismic zone between Mauna Loa and Kilauea volcano summits remained active with an average of about 10-40 earthquakes per week; these numbers may reflect increased seismic activity nearer Kilauea summit rather than increased Ka`oiki activity.
    • Volcanic History Overview: Massive Mauna Loa shield volcano rises almost 9 km above the sea floor to form the world's largest active volcano. Flank eruptions are predominately from the lengthy NE and SW rift zones, and the summit is cut by the Mokuaweoweo caldera, which sits within an older and larger 6 x 8 km caldera. Two of the youngest large debris avalanches documented in Hawaii traveled nearly 100 km from Mauna Loa; the second of the Alika avalanches was emplaced about 105,000 years ago (Moore et al. 1989). Almost 90% of the surface of the basaltic shield volcano is covered by lavas less than 4000 years old (Lockwood and Lipman, 1987). During a 750-year eruptive period beginning about 1500 years ago, a series of voluminous overflows from a summit lava lake covered about one fourth of the volcano's surface. The ensuing 750-year period, from shortly after the formation of Mokuaweoweo caldera until the present, saw an additional quarter of the volcano covered with lava flows predominately from summit and NW rift zone vents.
    • Location: Hawaii and Pacific Ocean, HI

      Latitude: 19.475
      Longitude: -155.608
      Elevation: 4170 m

      Recent Eruption: 1984
    • Hazard Assessments: Mullineaux, Donal Ray; Peterson, Donald W., 1974, Volcanic hazards on the Island of Hawaii, Open-File Report 74-239.
    • Link to monitoring data: Recent Earthquakes in Hawaii Page