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Alert Level: ADVISORY, Color Code: YELLOW
2017-09-21 19:40:16 UTC

U.S. Geological Survey
Thursday, September 21, 2017, 9:40 AM HST (Thursday, September 21, 2017, 19:40 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 deformation and seismicity have not changed significantly in the past week and persist at above-long-term-background levels.

Observations: Small-magnitude earthquakes continue to occur beneath the summit caldera and upper Southwest Rift Zone. These occurred primarily at shallow depths of less than 5 km (3 miles), with some additional deeper events at depths between 5-13 km (3-8 miles).

Global Positioning System (GPS) and satellite radar (InSAR) measurements continue to show deformation consistent with inflation of a magma reservoir beneath the summit caldera and upper Southwest Rift Zone.

No significant changes in volcanic gas emissions or summit fumarole temperature were measured.

For more information on current monitoring of Mauna Loa Volcano, see:

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.

Mauna Loa has erupted 33 times since its first well-documented historical eruption in 1843. Its most recent eruption was in 1984.


For more information on Mauna Loa and its hazards, see the USGS Fact sheet available at:

For information on activity at Kīlauea Volcano, please see:

HVO Contact:


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

Lava viewing information:
Hawai'i Volcanoes National Park:
County of Hawaii:
Kalapana lava-viewing area: 808-430-1966

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Lava Flow Maps:

Definitions of terms used in update:

Overview of Kīlauea summit (Halemaʻumaʻu) and East Rift Zone (Puʻu ʻŌʻō ) eruptions:

Summary of volcanic hazards from Kīlauea eruptions:

Recent Earthquakes in Hawai'i (map and list):

Explanation of Volcano Alert Levels and Aviation Color Codes:

HVO Contact:


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 Hawai`i.