Images

East Dome erupted during Sugar Bowl time (C.E. 850-900) east flank view of Mount St. Helens. Kalama age (erupted about 1535) andesite flows surround dome.

Mount St. Helens one year prior to the May 18, 1980, catastrophic eruption, showing glaciers at the summit.

Before the eruption of May 18, 1980, Mount St. Helens' elevation was 2,950 m (9,677 ft). View from the west, Mount Adams in distance. S. Fork Toutle River is valley in center of photo.

Mount Adams elevation is 3,745 m (12, 286 ft). Mount St. Helens was the smallest of five major volcanic peaks in Washington State.

Worm Complex on the southeast flank of Mount St. Helens—Middle Kalama lava flows in center of image. Photo from September 28, 1979. Click to view larger image.

Studebaker Ridge formed during the Tertiary geologic time period (65 million to 2.6 million years ago). The pyroclastic surge from the May 18, 1980 eruption destroyed the trees on the ridge.

The September 1977 eruption of Kīlauea began after nearly two years of dormancy, with activity breaking out on September 13 along a 3.5-mile-long fissure system between the prehistoric cones of Kalalua and Puʻu Kauka.

Three Fingered Jack (2390 m or 7840 ft) is a volcanic peak in central Oregon near Mount Bachelor and the Three Sisters. Black Butte is in the background.

Mount Konocti, a mostly dacitic composite cone, on the western shore of Clear Lake, California. Thurston Lake is in the foreground.

The magnitude-7.7 earthquake caused a nearly continuous zone of ground cracking and faulting for about 25 km (15 mi) along the south flank inland of Halapē.

A M 7.7 earthquake on November 29, 1975, was located beneath the south flank of Kīlauea.

Fractures in Crater Rim Road, Hawai‘i Volcanoes National Park, caused by the November 29, 1975, earthquake beneath the south flank of Kīlauea Volcano. Only a few meters (yards) from Kīlauea's summit crater (out of sight left of guardrails), large sections adjacent the crater wall slumped toward the crater, forming these fractures.

This part of the south flank of Kīlauea Volcano moved seaward about 6 m (20 ft) and subsided about 3.5 m (11.5 ft) as a result of the magnitude-7.7 earthquake. A tsunami swept ashore at Halapē and reached 14.6 m (48 ft) above the post-earthquake shoreline.

At 04:48 HST that morning, a magnitude-7.7 earthquake shook the island and generated a local tsunami that killed 2 people. Strong shaking from the earthquake produced damage at many locations on the Island of Hawai‘i. Within Hawai‘i Volcanoes National Park, sections of Crater Rim Drive (shown in this photo) cracked, some slumped toward the crater.

Ground cracks along Crater Rim Drive in Hawai‘i Volcanoes National Park caused by the M 7.7 earthquake on November 25, 1975. The cracks resulted from slumping of the ground toward the rim of Kīlauea Crater, the edge of which is left of the guardrails.

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 September 1974 Halemaʻumaʻu eruption was a brief but intense summit event at Kīlauea, erupting from fissures within the crater in a similar location to the 1971 eruption. Unlike the July 1974 eruption, this event featured a “curtain-of-fire” style lava fountain that advanced rapidly but stopped abruptly at the southwest wall of the caldera.

A three-day long eruption in July 1974 sent lava flows onto the floor of Kīlauea Volcano's summit caldera, where they spread out beneath the western caldera wall.

The July 19–22, 1974, Keanakākoʻi eruption was a dramatic summit event triggered by a sudden increase in seismicity and summit deflation. Lava fountains up to 180 feet high erupted from fissures north and south of Keanakākoʻi Crater and on the caldera floor, sending lava flows about 1.5 miles southward and across the caldera floor.

Low fountains and repeated overflows at the Mauna Ulu crater build the shield higher. Lava flows were mostly brief and short, thereby increasing the relief between the top of the shield and its base. The perched lava pond shown in the previous photo is bypassed by the two rivers.

Perched lava pond forming between Mauna Ulu and Pu'u Huluhulu, January 25, 1974. Several episodes of renewed growth in height of Mauna Ulu occurred in early 1974. The first sent much lava toward Pu'u Huluhulu, where a perched lava pond developed. This photo shows lava in the pond spilling over the enclosing levee and making it higher.

Note the two smaller vents on the west (left) side of the crater above the lake, which is about 150 m (500 ft) across.