Images

Dome building episode from 2004-2008 at Mount St. Helens can be observed and measured with these two digital elevation models (DEMs) developed before and after the eruptive episode.

Volcanic mudflows (lahars and debris flows) occur more commonly after a landscape has been covered by loose volcanic material. Sign on the slopes of Rabaul, Papua New Guinea.

Volcano Evacuation Route sign along a roadway in Washington State.

Distribution of young volcanic rocks by age in Haleakalā Crater, Maui.

Some of the large ballistic blocks from the Kīlauea eruption of 1924 later became visitor attractions. Many of these blocks remain in place today as evidence of the forces unleashed at Kīlauea during the eruption of 1924.

Top: Photograph of the SO2 camera installation when scientists tested the radio link to the Hawaiian Volcano Observatory (HVO). The camera is aimed at the plume emitting from the Overlook Crater, about 1.4 km away. Under typical trade wind conditions, the plume is blown to the southwest, thus moving from right to left in the imagery.

Seismic station locations (red triangles) on the Island of Hawai‘i and across the State of Hawaii (inset).

Earthquakes near the Island of Hawai‘i between 1970-2006 with magnitude greater than 2.5. A (top left): locations of shallow earthquakes 0-22 km (0-14 mi) depth. B (top right): locations of deep earthquakes 22-55 km depth (14-34 mi). Bottom (C): cross section showing the depths of earthquakes in the rectangle in figure B.

Scientist collects a sample of gas in a vacuum sealed glass bottle near Nymph Lake, Yellowstone National Park.

Moderate ash on corn crops from eruption of Tungurahua, Ecuador, 2007.

Due to the cataclysmic eruption of May 18, 1980, many of the locations annotated on this map are now either covered or no longer visible.

Non-volcanic peaks of the North Cascades lie in the background. Dusty Creek drainage experiences regular lahars. Gamma Ridge Formation are hydrothermally altered rocks on left ridge. Loose pyroclastic fill deposits cap right ridge; Eastern view, Glacier Peak, Washington.

Exposed rock ridges are thick Pleistocene lava flows that were confined between large glaciers. Glacier Peak, Washington, view north.

Information regarding volume and rates of advance for the crevassed Crater Glacier at Mount St. Helens, Washington, are extracted from Digital Elevation Models created from aerial photography. The red line shows the extent of Crater Glacier in 2012. Since 2012, the glacier has advanced about 50 m (160 ft) down the Loowit channel.

Summer geology intern Mindy Juergenson climbs over downed lodgepole pine trees killed in the fire of 1988 as she packs a GPS station out of the field (inset). Nine temporary stations are deployed each April/May and retrieved in October/November. The temporary stations supplement a network of permanent stations that record ground deformation data year-round.

Silica sinter (an amorphous form of silicon dioxide) forms from the waters that flow from hot springs near Shoshone Lake, Yellowstone National Park. USGS photograph by Jake Lowenstern.

Old Faithful geyser in eruption at Yellowstone National Park's Upper Geyser Basin.

GPS measurements provide models of the direction and rate (length of arrow) of deformation at the summit of Mauna Loa. Arrows pointing in multiple directions away from the summit indicate inflation.

Erratics located on a cinder cone on the northeast flank of Newberry Volcano, Oregon.

Volume of products, eruption cloud height, and qualitative observations (using terms ranging from "gentle" to "mega-colossal") are used to determine the explosivity value. The scale is open-ended with the largest volcanic eruptions in history (supereruptions) given magnitude 8.

HVO seismologists use this to review automatically generated earthquake parameters (location, depth, magnitude), measure P- and S-wave arrival times, and re-compute earthquake hypocenter and magnitudes for cataloging and distribution to the public.