USGS Volcano Notice - DOI-USGS-HVO-2022-08-04T10:13:58-07:00

HAWAIIAN VOLCANO OBSERVATORY WEEKLY UPDATE
U.S. Geological Survey
Thursday, August 4, 2022, 10:10 AM HST (Thursday, August 4, 2022, 20:10 UTC)

MAUNA LOA (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 seismicity temporarily increased above long-term background levels the evening of August 2, 2022, and returned to background levels by the morning of August 3, 2022. Other Mauna Loa monitoring data streams—ground deformation, gas concentrations, visual appearance in webcams—show no significant changes.

Observations:

During the past week, HVO seismometers recorded approximately 206 small-magnitude (below magnitude 3.0) earthquakes beneath the summit and upper-elevation flanks of Mauna Loa. The majority of these earthquakes occurred at shallow depths less than 9 miles (15 kilometers) below sea level.

Of the 206 earthquakes recorded over the past week, 90 were part of an earthquake swarm that occurred beneath Moku‘āweoweo, Mauna Loa’s summit caldera, from approximately 5:20 p.m. HST on August 2, 2022, until 3:00 a.m. HST on August 3, 2022. Most of these earthquakes occurred around 2 mi (3 km) below the surface and the largest event in the swarm was a magnitude-2.8.  During the earthquake swarm, a minor tilt increase of 1.5 microradians was observed on one tiltmeter (MOK) at the summit, though a small part of this signal includes normal diurnal effects.

Global Positioning System (GPS) measurements show steady rates of deformation in the volcano's summit region continuing through the past week.

This activity is a relatively small increase in volcanic unrest and remains within the range of fluctuations observed over the past several years. Prior to this activity, the most recent earthquake swarm beneath Mauna Loa summit occurred in the Spring of 2021, producing about a thousand earthquakes over a span of seven weeks with a peak seismicity rate of 40 earthquakes per day.

Concentrations of sulfur dioxide (SO2), hydrogen sulfide (H2S), and carbon dioxide (CO2), and fumarole temperatures remain stable at both the summit and Sulphur Cone (upper Southwest Rift Zone) gas stations.

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

HVO will continue to closely monitor Mauna Loa for changes.

For more information on current monitoring of Mauna Loa volcano, see: https://www.usgs.gov/volcanoes/mauna-loa/monitoring.

Background:
Mauna Loa is the largest active volcano on our planet, rising gradually to 4,170 meters (13,681 feet) above sea level. Its long submarine flanks descend an additional 5 kilometers (3 miles) 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 kilometers (5 miles). This places Mauna Loa's summit about 17,000 meters (56,000 feet) above its base. The enormous volcano covers half of the Island of Hawaiʻi and by itself amounts to about 85 percent of all the other Hawaiian Islands combined.

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 its first well-documented eruption in 1843, the volcano has erupted 33 times with intervals between eruptions ranging from months to decades. Mauna Loa last erupted 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
Mauna Loa webcam images: https://www.usgs.gov/volcanoes/mauna-loa/webcams
Mauna Loa photos/video: https://www.usgs.gov/volcanoes/mauna-loa/photo-and-video-chronology-mauna-loa
Mauna Loa maps: https://www.usgs.gov/volcanoes/mauna-loa/maps
Mauna Loa FAQs: https://www.usgs.gov/volcanoes/mauna-loa/faqs

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Summary of volcanic hazards from eruptions: https://www.usgs.gov/observatories/hvo/hazards
Recent earthquakes in Hawaiʻi (map and list): https://www.usgs.gov/observatories/hvo
Explanation of Volcano Alert Levels and Aviation Color Codes: https://www.usgs.gov/programs/VHP/volcanic-alert-levels-characterize-conditions-us-volcanoes

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.