Mauna Loa

HAWAIIAN VOLCANO OBSERVATORY WEEKLY UPDATE
U.S. Geological Survey
Thursday, July 11, 2019, 10:00 AM HST (Thursday, July 11, 2019, 20:00 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. Slightly elevated rates of deformation and seismicity have not changed significantly in the past week.

Observations: During the past week, approximately 95 small-magnitude earthquakes (less than M2.0) occurred beneath the summit and flanks of the volcano, compared to ~115 earthquakes the week before. Most earthquakes occurred at depths of less than 5 km (3 miles). Additional deeper seismicity at depths less than 10 km (6 miles) was primarily scattered beneath the southwest flank of the volcano.

Seismicity remains elevated, with an average of at least 50 shallow small-magnitude earthquakes per week following an earthquake swarm in October 2018. This compares to a rate of fewer than 20 earthquakes per week beneath the volcano in the first half of 2018.

Global Positioning System (GPS) and Interferometric Synthetic Aperture Radar (InSAR) measurements show continued summit inflation, suggestive of renewed recharge of the volcano’s shallow magma storage system. This rate of inflation has not changed since the alert level was raised on July 2nd, 2019, and remains consistent with increased rates of inflation following the October 2018 earthquake swarm.

No significant changes in volcanic gas release at Sulphur Cone on the Southwest Rift Zone were measured. Fumarole temperatures at both Sulphur Cone and at the summit remain unchanged.

Updates on the status of Mauna Loa Volcano will be issued each week on Thursdays until further notice.

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 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 km (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 Zones. 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: 1859, 1868, 1887, 1926, 1919, and three times in 1950.


MORE INFORMATION

Activity Summary also available by phone: (808) 967-8862

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

For more information on Mauna Loa and its hazards, see the USGS Fact sheet available at:
https://pubs.usgs.gov/fs/2012/3104/fs2012-3104.pdf

Webcam images: https://volcanoes.usgs.gov/volcanoes/mauna_loa/multimedia_webcams.html

Photos/Video: https://volcanoes.usgs.gov/volcanoes/mauna_loa/mauna_loa_multimedia_15.html

Monitoring data:
https://volcanoes.usgs.gov/volcanoes/mauna_loa/monitoring_summary.html

Explanation of Volcano Alert Levels and Aviation Color Codes:
https://volcanoes.usgs.gov/vhp/about_alerts.html
https://pubs.usgs.gov/fs/2006/3139/fs2006-3139.pdf

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.