Images

Mount St. Helens prior to the catastrophic eruption of May 18, 1980. Streams and lava flows also visible. View is looking southerly from oblique aerial view. Mount Hood in distance.

Oblique aerial photograph of source areas and runout paths of some of the devastating debris flows that were responsible for more than 20,000 fatalities in Vargas state, Venezuela, December 1999.

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.

Recent light detection and ranging (lidar) imagery has allowed us to identify and map a large number of previously unrecognized landslides, or slides, in heavily forested terrain in the western Columbia Gorge, Skamania County, Washington, and it has revealed that the few previously recognized areas of instability are actually composites of multiple smaller landslide

CalVO geologists Duane Champion and Drew Downs collect paleomagnetic samples from basalt lava flows at Eagle Lake

CalVO scientist Tom Sisson studies a lava flow in the Harrat Rahat Volcanic Field in Saudi Arabia for an international collaboration with the Saudi Geological Survey to conduct a seismic and volcanic hazard assessment for the volcanic field.

The older or original suggested location of this rift is shown with a blue dashed line. Black arrows show one possibility for the westward migration of the Nīnole Hills rift to the location of Mauna Loa's current Southwest Rift Zone (yellow dashed line). The South Kona Slump and ‘Ālika-1 and ‘Ālika-2 landslides are shown off the west coast of the island.

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.

Locations (Lat, Long, Depth) of January 17, 2010, earthquake swarm on Madison Plateau, Yellowstone National Park.

Guardian Geyser and Norris Geyser Basin, Yellowstone National Park.

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

Brimstone Basin, Yellowstone, aerial photo with overlay of two types of altered ground (light blue and pale pink shading) and locations of gas measurements (red dots). 2012 study

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

Three Sisters annotated photograph viewed from south to North from Broken Top, Oregon.

Remnant of Villard Glacier is in cirque below. Thick summit lava flow makes up "Glisan Pinnacle," which overlies hundreds of thin rubbly lava flows that are intercalated with red-oxidized agglutinate and scoria falls exposed on 800-m- (2600-ft-) high face below. Flows that form ridge at upper right are thicker than those on most of edifice.

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

Glacier Peak eruption history for the past 15,000 years.

Glacier Peak volcano, Washington reflected in pond below the Whitechuck Glacier, view from the south in late summer.

The orange layer just below geologist's hiking pole is the Mazama ash (about 7700 ybp). Below that are glacial deposits. Above the Mazama is about a meter consisting mostly of fine-grained tephras from Glacier Peak, capped by soil and plants. That the tephras sit directly on top of the Mazama indicates that "Dusty" eruptions commenced about 7,000 years ago.

Pyroclastic flow (dense darker grey billowing mass) travels down slope of Mayon volcano, Philippines while ash column rises from the vent. Dilute, lighter-colored ash billows off leading edge.