Mauna Loa

HAWAIIAN VOLCANO OBSERVATORY WEEKLY UPDATE
U.S. Geological Survey
Thursday, March 4, 2021, 9:51 AM HST (Thursday, March 4, 2021, 19:51 UTC)

MAUNA LOA VOLCANO (VNUM #332020)
19°28'30" N 155°36'29" W, Summit Elevation 13681 ft (4170 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

Activity Summary: Mauna Loa Volcano is not erupting. Rates of deformation and seismicity at the summit remain slightly elevated and above long-term background levels.

Observations:

During the past week, HVO seismometers recorded approximately 281 small-magnitude earthquakes—nearly all less than M2.5—below Mauna Loa, 220 of which were below the summit and upper-elevation flanks of the volcano. The majority of these summit and upper-elevation earthquakes occurred at shallow depths of less than 6 kilometers (approx. 4 miles) below ground level. These patterns of seismicity are typical of the past several weeks for Mauna Loa.

Global Positioning System (GPS) measurements continue to show slow, long-term summit inflation, consistent with magma supply to the volcano's shallow storage system. A slight increase in the rate of inflation at the summit that began in January is continuing.

Gas concentrations (0 ppm SO2) and fumarole temperatures (below 100 °C) at both the summit and at Sulphur Cone on the Southwest Rift Zone remain stable.

Webcam views have shown no changes to the volcanic landscape on Mauna Loa over the past week.

For more information on current monitoring of Mauna Loa Volcano, see: https://volcanoes.usgs.gov/volcanoes/mauna_loa/monitoring_summary.html

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Background: Mauna Loa is the largest active volcano on our planet, rising gradually to 4,170 m (13,681 ft) above sea level. Its long submarine flanks descend an additional 5 km (3 mi) below sea level to the ocean floor. The ocean floor directly beneath Mauna Loa is, in turn, depressed by the volcano's great mass another 8 km (5 mi). This places Mauna Loa's summit about 17,000 m (56,000 ft) above its base. The enormous volcano covers half of the Island of Hawaiʻi.

Eruptions typically start at the summit and, within minutes to months of eruption onset, about half of the eruptions migrate into either the Northeast or Southwest Rift Zone. Since 1843, the volcano has erupted 33 times with intervals between eruptions ranging from months to decades. Mauna Loa last erupted 35 years ago, in 1984.

Mauna Loa eruptions tend to produce voluminous, fast-moving lava flows that can impact communities on the east and west sides of the Island of Hawaiʻi. Since the mid-19th century, the city of Hilo in east Hawaiʻi has been threatened by seven Mauna Loa lava flows. Mauna Loa lava flows have reached the south and west coasts of the island eight times: in 1859, 1868, 1887, 1926, 1919, and three times in 1950.

MORE INFORMATION:

Mauna Loa activity summary also available by phone: (808) 967-8866

Other Hawaiian volcanoes summary also available by phone: (808) 967-8877

Subscribe to these messages: https://volcanoes.usgs.gov/vns2/

Mauna Loa webcam images: https://www.usgs.gov/volcanoes/mauna-loa/webcams

Mauna Loa photos/video: https://www.usgs.gov/volcanoes/mauna-loa/photo-video-chronology

Mauna Loa FAQs: https://volcanoes.usgs.gov/observatories/hvo/faq_maunaloa.html

Summary of volcanic hazards from eruptions: https://volcanoes.usgs.gov/observatories/hvo/hawaii_hazards.html

Recent earthquakes in Hawaiʻi (map and list): https://www.usgs.gov/observatories/hawaiian-volcano-observatory/earthquakes

Explanation of Volcano Alert Levels and Aviation Color Codes: https://www.usgs.gov/natural-hazards/volcano-hazards/about-alert-levels


CONTACT INFORMATION:

askHVO@usgs.gov

The Hawaiian Volcano Observatory is one of five volcano observatories within the U.S. Geological Survey and is responsible for monitoring volcanoes and earthquakes in Hawaiʻi.