Images

This view of Mauna Loa's summit is looking toward the northeast. The east flank of Mauna Kea is to the left, and North Pit, on the northeast end of Moku‘āweoweo, is straight ahead.

This view of Mauna Loa's 1940 vent cone, looking to the southwest, shows a fissure that bisected it during the 1984 eruption (crack on the right side of the cone). Pāhoehoe flows and spatter erupted from the 1984 fissure blanket the caldera floor northwest of the cone (foreground).

A close-up view of the 1984 fissure that cut through the southwest side of Mauna Loa's 1940 vent cone. The crack on the right side of the cone is the 1984 fissure.

Aerial view of Mauna Loa's upper northeast rift zone near the area where it intersects Moku‘āweoweo, the summit caldera. Pāhoehoe flows visible in the foreground were erupted in 1942. Distant steep cliffs (right background) are the west wall of the summit caldera.

A view of Moku‘āweoweo, the summit caldera of Mauna Loa, as seen from South Pit (looking to the north-northwest). An eruption in 1940 created the cinder-and-spatter cone visible on the caldera floor (right center). This cone, which is about 114 m (373 feet) high, is the largest cone at Mauna Loa's summit.

View looking downslope at the various cones that dot Mauna Loa's Northeast Rift Zone. The edge of North Pit, on the north side of Moku‘āweoweo, is in the foreground.

The high point of Mauna Loa, in the background at an elevation of about 13,679 ft, is actually just the highest point along the rim of the steep cliffs that surround Mauna Loa's summit caldera, Moku‘āweoweo, Dark-colored lava flows of recent vintage (1984) cover the floor of Moku‘āweoweo. View is looking southwest.

This aerial view of Mauna Loa's summit shows the cinder-cone and lava flows that were erupted in 1949. The crack extending down the left side of the cone is the northeast-southwest trending 1984 fissure that bisected the southwest flank of the cone during the initial phase of the eruption. Light-brown tephra erupted from the 1949 cone thins to the west.

An aerial view of the 1940 cinder-and-spatter cone on the floor of Mauna Loa's summit caldera as seen from the southeast. The west wall of the caldera (background) is about 170 m (560 feet) high. Most of the caldera floor around the cone is covered by lava flows erupted in 1984.

Solar-powered seismic station located near the summit of Mauna Loa Volcano, Hawai‘i.

On July 6, 1975, eruptive fissures opened along Mauna Loa

Lava fountains up to 20 m (65 ft) high erupted from fissures on the north flank of Mauna Loa early Sunday morning, July 6, 1975. USGS photo.

Lava fountains erupt from a fissure in the southwestern part of Moku`aeoweo, Mauna Loa's summit caldera, on April 11, 1940 (view looking to the south-southeast). Patches of white snow cling to the caldera walls as fluid pahoehoe lava flows spread across

Maps showing lava flow progression during the 1984 eruption of Mauna Loa. These maps were featured in the Hawai‘i Tribune-Herald newspaper on March 27, 1984 (top) and March 30, 1984 (bottom). 

Lava production from these "2,900-m vents" began to decrease in late March but declined most rapidly between April 7 and 9 from about 300,000 m3 per hour to less than 100,000 m3 per hour. Photo taken at 9:09 a.m.

Lava flows from the 1984 eruption of Mauna Loa loom above the town of Hilo. Photograph taken near the Hilo airport on April 4.

Pohaku Hanalei cinder-spatter cone (upper left) is located about 3.2 km (2 mi) NE from the north edge of the caldera rim. Eruption rates were as high as 2.9 million m3 per hour during the first 6 hours of the eruption, then diminished to about 0.5 million m3 per hour for the next 12 days.

Aa lava flows erupting from Mauna Loa.

(Left) Aerial photograph of the Pāhala area, on the southern side of the Island of Hawaiʻi, taken on December 11, 1976. (Right) The backside of the same photo showing labeled field locations, marked with a pinhole through the photograph, which correspond to the geologist’s field notes. 

Mauna Loa 1975 eruption. Lava fountains up to 20 m (65 ft) high erupted from fissures on the north flank of the volcano early Sunday morning, July 6, 1975.

The Ka‘apuna flow traveled from the Southwest Rift Zone vent (7,800 ft elevation) to the coast in just 17 hours.