Mauna Loa

HAWAIIAN VOLCANO OBSERVATORY WEEKLY UPDATE
U.S. Geological Survey
Thursday, January 21, 2021, 9:31 AM HST (Thursday, January 21, 2021, 19:31 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 have not changed significantly over the past week and remain above long-term background levels.

Observations:
During the past week, HVO seismometers recorded 56 small-magnitude earthquakes on the volcano's summit and upper-elevation flanks. Most of these earthquakes occurred at shallow depths of less than 8 kilometers (~5 miles) below ground level. The largest recorded earthquake was a M2.9, just east of the summit caldera, on January 18, at 22:26 p.m. HST.

Global Positioning System (GPS) measurements show continued slow summit inflation, consistent with magma supply to the volcano’s shallow storage system.

Gas concentration at the Sulphur Cone monitoring site remain stable (below 2 ppm SO2). Fumarole temperature was ~96 C. This value is in the normal range.

Webcams show no changes to the landscape.

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 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:

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

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

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

Kilauea Webcam images: https://www.usgs.gov/volcanoes/kilauea/webcams

Kilauea Photos/video: https://www.usgs.gov/volcanoes/kilauea/photo-video-chronology

Kilauea Lava flow maps: https://www.usgs.gov/volcanoes/kilauea/maps

Haleakala Summary: https://www.usgs.gov/volcanoes/haleakala

Hualalai Summary: https://www.usgs.gov/volcanoes/hualalai

Loihi Summary: https://www.usgs.gov/volcanoes/loihi-seamount

Mauna Kea Summary: https://www.usgs.gov/volcanoes/mauna-kea

Definitions of terms used in update: https://volcanoes.usgs.gov/volcanoes/kilauea/extra/definitions.pdf

Summary of volcanic hazards from Kīlauea eruptions: https://volcanoes.usgs.gov/volcanoes/kilauea/extra/hazards.pdf

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.