Hazard Notification System (HANS) for Volcanoes


U.S. Geological Survey
Thursday, September 29, 2022, 2:26 PM HST (Friday, September 30, 2022, 00:26 UTC)

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 remain elevated above long-term background levels. Other Mauna Loa monitoring data streams—ground deformation, gas concentrations, visual appearance in webcams—show no significant changes. 


During the past week, HVO seismometers recorded over 400 small-magnitude (below M3.0) earthquakes below the summit and upper-elevation flanks of Mauna Loa. Most earthquakes occurred beneath Moku‘āweoweo, Mauna Loa’s summit caldera, at depths of 1-2 mi (2-3 km) below the surface. This increase in seismicity does not mean that an eruption is imminent nor that progression to an eruption is certain.  

Elevated earthquake activity under Mauna Loa began in mid-2022 but intensified at approximately 2 a.m. HST on September 23, 2022. Earthquakes have continued at rates of about 50 per day. This represents an increase compared to an average of 15 earthquakes per day prior to this swarm. Most earthquakes have been smaller than magnitude-2 and are unlikely to be felt or cause damage; the largest event in the swarm so far was a magnitude-2.8 on September 23 (https://earthquake.usgs.gov/earthquakes/eventpage/hv73149937/).  

A minor ground tilt signal was recorded coincident with this swarm. Ongoing tilt changes are difficult to separate from ground motions due to daily heating/cooling cycles and strong seasonal signals. This tilt excursion is smaller than one that accompanied an earthquake swarm in August 2022, and both are smaller than one that occurred in March 2021 that was the subject of a Volcano Watch: https://www.usgs.gov/observatories/hvo/news/volcano-watch-mauna-loa-sleeping-giant.  

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

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

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

Increases in seismic activity have been detected previously at Mauna Loa with no subsequent eruptions. We expect additional shallow seismicity and other signs of unrest to precede any future eruption, if one were to occur. 

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.

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

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 and American Samoa.


HVO, askHVO@usgs.gov—best contact for regular reporting and questions. 
Ken Hon, HVO Scientist in Charge, USGS khon@usgs.gov
Natalia Deligne, American Samoa Lead Responding Scientist, USGS ndeligne@usgs.gov 

Subscribe to these messages: https://volcanoes.usgs.gov/vns2/
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
Volcanoes of American Samoa: https://www.usgs.gov/observatories/hvo/volcanoes-american-samoa
Explanation of Volcano Alert Levels and Aviation Color Codes: https://www.usgs.gov/programs/VHP/volcanic-alert-levels-characterize-conditions-us-volcanoes