Images

Aerial view of Mauna Loa erupting on the morning of March 25, 1984, the first day of the volcano's most recent eruption. The lava flow was advancing southeast, toward Kīlauea, from fissure vents at an elevation of about 11,200 feet on Mauna Loa's Northeast Rift Zone. Moku‘āweoweo, Mauna Loa's summit caldera, is visible at top left.

A USGS Hawaiian Volcano Observatory geologist monitored the advance of an ‘A‘ā lava flow on April 6 during the 1984 Mauna Loa eruption. This flow was about 4 m (13 ft) high and advancing at a rate of 50 m (55 yards) per hour. Lava reached within 6 km (4 mi) of Hilo city limits before the 22-day-long eruption ended on April 15.

USGS Hawaiian Volcano Observatory field engineers begin the process of lowering a tiltmeter into a deep borehole on the west flank of Mauna Loa. The installation is guided by a custom-built apparatus that includes a 3-D printed jig. This tiltmeter will help monitor the currently elevated activity of Mauna Loa Volcano. USGS photo.

Charcoal collected from under the base of a pāhoehoe flow in a black sooty zone over orange ash.  The black sooty zone represents the region where the vegetation was converted to charcoal.  The hammer is approximately 13 inches long. USGS photo by F. Trusdell. 

A beautiful sunset over Mauna Loa (in distance at left) provided a backdrop to the lava lake within Halema‘uma‘u. HVO and Jaggar Museum are on the horizon near the center of the panorama.

"Geologic map of the northeast flank of Mauna Loa volcano, Island of Hawai‘i," published by the U.S. Geological Survey in May 2017, shows the distribution of lava flows and other deposits covering an area from Pu‘u‘Ula‘ula ("Red Hill") on the southwest to Hilo on the northeast.

Interferometric Synthetic Aperture Radar (InSAR) images of Kīlauea (left) and Mauna Loa (right) spanning the past several years. Concentric patterns of colored fringes indicate magma accumulation centered near the summit calderas of both volcanoes.

USGS scientists hiked to the summit of Mauna Loa, where they checked on HVO's monitoring instruments and realigned an antenna that allows webcam images of the volcano's summit caldera (shown in this panoramic image) to be posted on the HVO website.

Inundation zones shown on map sheets as numbered colored boxes.

The gentle slope of Mauna Loa as seen from the flanks of Mauna Kea to the north. Younger lava flows appear dark on the volcano's flank, and clouds rest in the eastern saddle between the two volcanoes.

This panoramic view of the 1935 Humu‘ula flow (black lava) on both sides of the Daniel K. Inouye Highway, which runs east to west in the saddle between Mauna Loa (snow-capped shield volcano at far left) and Mauna Kea (distant right), was taken from the top of Pu‘uhuluhulu. View is to the northwest. The top of Hualālai is visible in far distance (center).

A young 'ua'u exercises its wings in preparation for its first flight directly out to sea. The 'ua'u, or Hawaiian petrel, is a federally endangered native seabird that nests at high elevations on Mauna Loa volcano.

This photo, taken by Thomas Jaggar on December 21 during the1935 Mauna Loa eruption, shows the Humuula pāhoehoe flow ponding and slowly expanding eastward. The image looks east-southeast toward Pu‘uhuluhulu from the southernmost Omaokoili cinder cone in the vicinity of today's Saddle Road and Mauna Kea Access Road juncture. USGS photo.

Mauna Loa March 25, 1984 eruption.

This rapidly moving ‘A‘ā lava flow was one of several that advanced down the west flank of Mauna Loa during the volcano's 1950 eruption. The massive flow, tens of meters (yards) high, traveled from the Southwest Rift Zone vent to the ocean, a distance of about 18 km (11 mi), in around 18 hours.

A USGS Hawaiian Volcano Observatory chemist conducts thermal imaging measurements as part of a geochemical survey on Mauna Loa's upper Southwest Rift Zone in March 2016. Areas like the one shown here can indicate where gases are escaping from magma at depth. USGS photo.

During the Mauna Loa 1950 eruption, three large, fast-moving lava flows advanced down the west flank of the volcano, each crossing the main highway before reaching the ocean. The Ka‘apuna flow, shown here, traveled from the Southwest Rift Zone vent (7,800 ft elevation) to the coast in just 17 hours, creating a huge steam plume as lava flowed into the sea.

One of the new tools deployed by the USGS Hawaiian Volcano Observatory to better monitor the current unrest on Mauna Loa is a webcam focused on the volcano's Southwest Rift Zone, which has been the site of eruptions in 1903, 1916, 1919, 1926, and 1950.

As the sun rose above Mauna Kea (background) on July 6, 1975, eruptive fissures along the Northeast Rift Zone of Mauna Loa fed voluminous ‘a‘ā lava flows that quickly moved down the north flank of the volcano.

Though the park celebrates its 100th anniversary on August 1, 2016, its main attractions-Kilauea and Mauna Loa volcanoes-have been adding to the land mass of Hawaii’s “Big Island” for at least 400,000 years.

TOP: Mauna Loa weekly earthquake rates between 2010 and September 17, 2015. Blue bars indicate the number of earthquakes that were located by the USGS Hawaiian Volcano Observatory seismic network. Earthquakes of all magnitudes are plotted. Subtle increases in earthquake rates started in mid-2013, while more obvious changes in rates started in 2014.