Images

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.

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.

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.

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

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.

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.

Rock and ice debris avalanche (October 20, 1997) on the east side of Mount Adams.

A tumulus in the Coso Volcanic Field, California. This lava was probably more viscous than the lava found in the Hawaii tumuli.

Detail of levee on an active channelized aa flow. Note the pahoehoe overflows in the levees and the level of the active flow below the tops of the levees. This lower flow level is not allowed in the commonly used "Bingham" model of lava flows.

Mt. Konocti erupted during the most recent stage of volcanism (01. Ma to 10,000 years ago), and a future eruption from the same site would be devastating to the nearby inhabitants.

Photograph of the large jökulhlaup that spread out across Skeiðarársandur (glacial outwash plain) from the terminus of Skeiðarárjökull, an outlet glacier of Vatnajökull.

Lava fragments explode onto the sides of a littoral cone on the south coast of Kīlauea Volcano as lava pours into the sea from a lava tube.

Mount Konocti, the most distinct volcanic feature of the Clear Lake Volcanics as viewed to the west from Cinder Cone.

Lahars pick up material as they travel, which can cause damage to structures in their path. Damage here from Mt. Pinatubo, Philippines.

Queen's Laundry bathhouse, in the Lower Geyser Basin of Yellowstone National Park.  Building began under superintendent Philetus Norris in 1881 but was never finished.

Lassen Peak's Devastated Area photographed from the air in 1994.

Two bubble bursts explode simultaneously as a consequence seawater mixing with lava in a lava tube beneath surface of a lava delta. Because of the confined conditions in the lava tube, explosive pressures build up as water, heated by contact with molten lava, expands instantly to steam.

Hummocks on West Island, Alaska, 8 km (5 mi) WNW from Augustine Volcano summit. These small hills were deposited as part of the 1883 debris avalanche (landslide) that triggered a Cook Inlet tsunami.

Roiling eruption column rising from Crater Peak vent of Mt. Spurr volcano. View from the south.

USGS hydrologist Michael Sorey tries to locate the steam vent at a fumarole in the Bumpass Hell area in Lassen Volcanic National Park.

Steamboat Geyser in the steam-phase of an eruption on June 4, 2018, Norris Geyser Basin, Yellowstone National Park. Photo by Jamie Farrell (University of Utah).