Activity Summary: Mauna Loa volcano is not erupting. Rates of seismicity remain slightly elevated above long-term background levels, but have not changed significantly over the past week. 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 approximately 62 small-magnitude (below M3.0) earthquakes below the summit and upper-elevation flanks of Mauna Loa. All of these earthquakes occurred at shallow depths less than 15 kilometers (9 miles) below sea level.
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.
For more information on current monitoring of Mauna Loa volcano visit the USGS website.
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.