Volcano Hazards Program Office

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Photo taken from the air, looking down on red hot lava fountaining up from a vent, then running in red channels down a slope.
April 22, 1985

Aerial view of waning lava fountain, Kilauea Volcano, 1985

Aerial view, from the east, of waning lava fountain from Pu'u 'O'o on Hawai'i Island's Kilauea Volcano. Taken at the end of eruption episode 32. Pu'u 'O'o rose 209 meters above the pre-1983 surface (928 meters above sea level).

Mount St. Helens four years after the May 18, 1980 eruption—lava do...
September 24, 1984

Mount St. Helens four years after the May 18, 1980 eruption—lava do...

Mount St. Helens four years after the May 18, 1980 eruption—lava dome in the crater and drainage channels development on flanks; view from Johnston Ridge.

Lava fountain 450 m (1,475 ft) high from Kīlauea Pu‘u ‘Ō‘ō eruption...
September 19, 1984

Lava fountain 450 m (1,475 ft) high from Kīlauea Pu‘u ‘Ō‘ō eruption...

Lava fragments ejected by lava fountains are called tephra, a general term for all fragments, regardless of size, that are blasted into the air by explosive activity. A variety of terms are also used to describe specific types of fragments, including Pele's hair, Pele's tears, scoria, spatter, bombs, and reticulite. Other terms are used to describe the size of fragments,

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Fireweed, growing in Mount St. Helens' devastated area; view from t...
August 15, 1984

Fireweed, growing in Mount St. Helens' devastated area, Summer 1985

Vegetation began reappearing as early as the summer of 1980 as many small trees and plants were protected by the snowpack on May 18. Seeds, carried by the wind or by animals, also entered the area and grew. By 1985, the ridges surrounding the volcano were covered with new growth.

Measurements of the magnetic field surrounding the Mount St. Helens...
June 18, 1984

Measurements of magnetic field surrounding the Mount St. Helens' dome

The strength of the magnetic field increased as the dome cooled and magnetic minerals formed. During the eruptions the strength usually changed rapidly as magma heated and deformed the dome.

Low lava fountains from 1984 Mauna Loa "2,900-m vents" signaled dec...
April 8, 1984

Low lava fountains from 1984 Mauna Loa "2,900-m vents" signaled dec...

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 ...
April 4, 1984

Lava flows from the 1984 eruption of Mauna Loa loom above the town ...

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

April 2, 1984

Mauna Loa Lava Flow, April 2, 1984

A USGS scientist walks along a lava flow from the April 2, 1984 Mauna Loa eruption. The scientist stops to observe a standing wave of lava at the end. The lava flow is moving at 64 km/hr (40 mph) towards Hilo, Hawai'i. 
 

Image: Lava flows on Mauna Loa
March 25, 1984

Lava flows on Mauna Loa

Erupting vents on Mauna Loa’s northeast rift zone near Pu‘u‘ula‘ula (Red Hill) on Mar. 25, 1984, sent massive ‘a‘ā lava flows down the rift toward Kūlani.

Lava fountains erupting from fissure on upper northeast rift zone o...
March 25, 1984

Lava fountains erupting from fissure on upper northERZ of Mauna Loa...

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. Sizable pahoehoe flows formed only during the first day of the eruption and within a

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