Images

Eruptions in the Cascade Range during the past 4000 years. USGS GIP 64

Side-by-side comparison of the northwest wall of Kīlauea Caldera on a clear day (left) and a day with thick vog (right). HVO observation tower and building can be seen near the center in each photo.

Medicine Lake lies within the shallow basin of Medicine Lake caldera. Glass Mountain flow, draped over the east side of the volcano, is the youngest lava flow at the volcano. The northeasternmost dacite tongue extends nearly to the bottom of the photo (distal lobes are outlined to enhance visibility).

Vog obscures view during slack or no tradewinds at the summit of Kīlauea Volcano, Hawai‘i

HVO geologist downloads images collected with infrared cameras set up on the rim of Halema‘uma‘u Crater. The cameras are aimed at an erupting lava lake to conduct a thermal survey of the lake's surface.

Seismologist installing equipment at station NED on Mount St. Helens, Washington. Mount Rainier in distance.

Sulfur flow (darker gray area) on an altered ground surface at Brimstone Basin, Yellowstone Lake in background.

Gas flows up, appearing to boil, through the water of Alluvium Creek, Brimstone Basin, Yellowstone. Large funnel is used to trap gas, which is then sent to a collection bottle through the tubing.

Gas flux measurement being taken over altered ground at Brimstone Basin, Yellowstone.

Hawaiian Volcano Observatory field geologists track activity at fissure 8 (pictured in the background). Crews collect fissure 8 tephra (Pele's hair, pumice, and other lightweight volcanic glass fragments) for geochemical analyses and characterization of changes in lava fountain behavior.

The U.S. Geological Survey's Hawaiian Volcano Observatory, the first volcano observatory in the United States, is located on the west rim of Kīlauea Volcano's summit caldera in Hawai‘i Volcanoes National Park. A volcanic gas plume rises from a vent that opened in 2008 at the base of the south wall of Halema‘uma‘u Crater. Crater Rim Drive in foreground.

The USGS Hawaiian Volcano Observatory (foreground) is located on the caldera rim of Kilauea Volcano, Hawai'i—the most active volcano in the world.  The observatory's location provides an excellent view of summit eruptive activity, which began in 2008.

The USGS Hawaiian Volcano Observatory (foreground) is located on the caldera rim of Kilauea Volcano, Hawai'i—the most active volcano in the world.  The observatory's location provides an excellent view of summit eruptive activity, which began in 2008.

The Hawaiian Volcano Observatory, the first volcano observatory in the United States, is located on the west rim of Kīlauea Volcano's summit caldera in Hawai‘i Volcanoes National Park. A volcanic gas plume rises from a vent that opened in 2008 at the base of the south wall of Halema‘uma‘u Crater. Crater Rim Drive in foreground.

The Hawaiian Volcano Observatory perched on the west rim of Kīlauea Volcano's summit caldera, overlooks Halema‘uma‘u Crater, where a new vent that opened in March 2008 emits a volcanic gas plume.

Volcanic-gas plumes mark the sites where lava flows from Pu‘u ‘Ō‘ō enter the ocean on Kīlauea's south coast (far left), the Pu‘u ‘Ō‘ō cone (left) on the East Rift Zone, and Halema‘uma‘u Crater at the summit (right). Structures visible in middle left primarily located around the Volcano Golf and Country Club and Kīlauea Military Camp.

Lidar instrument uses light pulses to measure distances to the ground surface in the Kīlauea Caldera, Hawaii. Measurements are used to make a Digital Elevation Model - a very accurate topographic map.

Narrow Gauge spring, Mammoth Hot Springs, Yellowstone National Park.  Vent area is between the two trees on top of the travertine deposits.  Terraced pools form due to deposition of travertine from the fluids as they cool and degas carbon dioxide.

Incandescent arcs trace the path of lava fragments cast out during a tephra-jet explosion at the Waikupanaha ocean entry in 2008. This is a relatively small explosion, reaching a few tens of meters (yards) height, while one earlier in the day was nearly 70 meters (230 ft) in height.

When lava from the Pu'u 'Ō'ō-Kupaianaha eruption, active since 1983, meets the ocean, large littoral explosions can result.

The early morning helicopter overflight of the lower East Rift Zone shows lava continuing to enter the sea at Ahalanui. The southern margin of the flow remains about a quarter mile from the boat ramp at Isaac Hale Park (jetty visible in the center left of the photo). View to the northeast.