Images

NASA Astronaut image of Ta'u Island (Manu'a Islands, American Samoa) in the South Pacific Ocean.

About 130 mm (5 inches) of peak uplift from 1995 to 2001 is shown in this interferogram in the Three Sisters Wilderness. Magma accumulating at about 7 km (about 4.5 mi) depth is the likely cause of uplift. The area of uplift, about 20 km (12 miles) in diameter, is almost entirely within the wilderness area.

Sherman Crater, to the left of the true summit, at Mount Baker, Washington, aerial view to the northwest.

Mount Baker, aerial view to the northeast.

James (Jim) Vallance is a Geologist with the USGS Volcano Science Center. He is based at the Cascades Volcano Observatory.

Known eruptive episodes at Glacier Peak during the past 15,000 years. Each episode (depicted by a single icon) represents many individual eruptions. The ages of these episodes, in calendar years before present are corrected from dates based on a radiocarbon time scale.

Note the protruding logs and branches from living trees that were knocked down and carried by the lahar. Ice axe, 3 ft, shows scale. Lahars are the greatest hazard at Mount Baker.

Potential volcanic hazards at Mount Baker.

Timeline for eruptions at Mount Baker during the Holocene (12,000 years ago to present).

Mount Hood lies approximately 70 km (45 mi) from Portland International Airport. Ash can cause jet engines to fail, and air traffic may be grounded during an eruption.

Map of volcanic ashfall. Areas of the United States that once were covered by volcanic ash from Yellowstone's giant eruptions 2 million and 630,000 years ago, compared with ashfall from the 760,000-year-old Long Valley caldera eruptions at Mammoth Lakes, California, and the 1980 eruption of Mount St. Helens, Washington.

Craters of the Moon, Idaho, Landsat 7 true-color image viewed from the east. Pioneer Mountain Range along the western border. Image created by NASA EArth Observatory.

Cutaway views showing the internal structure of the Earth. Left: To scale drawing shows that Earth's crust is very thin. Right: Not to scale, more detail of three main layers (crust, mantle, core).

Photograph from the southwestern wall of the Grímsvötn caldera in Vatnajökull on December, 19 1998.

USGS geochemist Bill Evans measures the temperature of a superheated (hotter than the boiling point) fumarole in Lassen Volcanic National Park.

Profile of Mauna Kea showing inferred contact (dot-dashed line) between postshield-stage Hamakua Volcanics and underlying shield-stage lavas. Approximate contact with Laupahoehoe Volcanics dashed.

During prevailing trade wind conditions, the nearly constant stream of volcanic smog (vog) produced by Kīlauea Volcano on the Island of Hawai‘i is blown to the southwest and west. The trade winds (blue arrows) blow the vog from its main source on the volcano (white plume) to the southwest, where wind patterns send it up the island's Kona coast.

An aerial view looking south of the Long Valley volcanic region in the area of Mono Lake, showing a line of rhyolite lava domes and explosion craters. An inset map shows the locations of silcic magmatic centers in the Long Valley area.

Volcanic gases react with the atmosphere in various ways; the conversion of sulfur dioxide (SO2) to sulfuric acid (H2SO4) has the most significant impact on climate.

Geologic map of Mauna Kea, showing generalized distribution of lava flows, cinder cones, and glacial deposits of the Laupahoehoe Volcanics.

Geologic map of Mauna Kea with generalized surface distribution of Hamakua Volcanics. Laupahoehoe Volcanics are inferred to overlie a vast area of Hamakua Volcanics on the upper flanks and summit.