Images

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.

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.

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.

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.

View looking up Mauna Loa's spectacular Southwest Rift Zone. Pu‘u o Keokeo fills the lower half of the photo. The black lava beyond is mostly from 1916 and 1926. The summit of Mauna Loa is in the background.

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).

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.

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.

View from just below the summit of Mauna Loa looking back down the Southwest Rift. The Sulfur Cone is the white area just above center frame. Pu‘u o Keokeo is the barely visible bump just above Sulfur Cone at the crest of the Southwest Rift.

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.

This edge of the cliff above Moku‘āweoweo, at an elevation of 13,661 feet, is only a few feet lower than Mauna Loa's high point (out of sight to the left). The cliff here is about 600 feet high. Mauna Kea, in the background to the right rises to an elevation of 13,796 feet, barely 100 feet higher the summit of Mauna Loa.

The 1949 cinder-and-spatter cone (left) and 1940 spatter cone (right) as seen from the floor of Mauna Loa's summit caldera, looking to the southwest. Pāhoehoe flows in the foreground were erupted in 1984.

Close-up of the 1949 cinder-and-spatter cone as seen from the floor of Moku‘āweoweo, Mauna Loa's summit caldera. pāhoehoe lava visible in the foreground (lower half of photo) was erupted in 1940. Beyond these flows, you can see pāhoehoe flows, spatter, and tephra erupted in 1949.

The 1940 cinder-and-spatter cone as seen from the caldera floor looking to the southeast. This cone, which is about 114 m (373 feet) high, was built around the vent as lava spewed from it over a period of 134 days. The dark-colored pāhoehoe flows visible in the foreground were erupted in 1984.

Sulfur, not snow, paints the ground white in the Sulfur Cone area on Mauna Loa's upper Southwest Rift Zone. The summit of Mauna Loa is over the slope of the mountain out of sight to the left in the background.

The 1940 cone, just above center, pokes up above the otherwise relatively flat floor of Moku‘āweoweo - the summit caldera of Mauna Loa. Mauna Kea rises up in the background.

USGS employees deploys a water conductivity/temperature/depth probe (AquaTroll) for a temporary study along the Madison River, Yellowstone.

A complex configuration has been in place deep within the vent cavity in Halema`uma`u crater. Lava upwells in the west portion of the vent floor (upper left of photograph), feeding the small, crusted, circular lava lake.

A close-up of the swiftly moving lava stream, plunging into the lava lake.

The western Kamoamoa fountain-fed lava flows advanced over 1997 lavas (dark flow in foreground) with 1965 and 1968 lavas buried by Pu‘u ‘Ō‘ō cinder to the far left. Pu‘u ‘Ō‘ō is in the distant background.