Long Valley Caldera is a depression in eastern California that is adjacent to Mammoth Mountain. The valley is one of the Earth's largest calderas, measuring about 20 mi (32 km) long (east-west), 11 mi (18 km) wide (north-south), and up to 3,000 ft (910 m) deep.
A fumarole is a vent in the surface of the Earth or another rocky planet from which hot volcanic gases and vapors are emitted, without any accompanying liquids or solids. Fumaroles are characteristic of the late stages of volcanic activity, but fumarole activity can also precede a volcanic eruption and has been used for eruption prediction. Most fumaroles die down within a few days or weeks of the end of an eruption, but a few are persistent, lasting for decades or longer. An area containing fumaroles is known as a fumarole field.
A stratovolcano, also known as a composite volcano, is a typically conical volcano built up by many alternating layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and explosive eruptions. Some have collapsed summit craters called calderas. The lava flowing from stratovolcanoes typically cools and solidifies before spreading far, due to high viscosity. The magma forming this lava is often felsic, having high to intermediate levels of silica, with lesser amounts of less viscous mafic magma. Extensive felsic lava flows are uncommon, but can travel as far as 8 km (5 mi).
The geothermal areas of Yellowstone include several geyser basins in Yellowstone National Park as well as other geothermal features such as hot springs, mud pots, and fumaroles. The number of thermal features in Yellowstone is estimated at 10,000. A study that was completed in 2011 found that a total of 1,283 geysers have erupted in Yellowstone, 465 of which are active during an average year. These are distributed among nine geyser basins, with a few geysers found in smaller thermal areas throughout the Park. The number of geysers in each geyser basin are as follows: Upper Geyser Basin (410), Midway Geyser Basin (59), Lower Geyser Basin (283), Norris Geyser Basin (193), West Thumb Geyser Basin (84), Gibbon Geyser Basin (24), Lone Star Geyser Basin (21), Shoshone Geyser Basin (107), Heart Lake Geyser Basin (69), other areas (33). Although famous large geysers like Old Faithful are part of the total, most of Yellowstone's geysers are small, erupting to only a foot or two. The hydrothermal system that supplies the geysers with hot water sits within an ancient active caldera. Many of the thermal features in Yellowstone build up sinter, geyserite, or travertine deposits around and within them.
Nevado del Ruiz, also known as La Mesa de Herveo is a volcano on the border of the departments of Caldas and Tolima in Colombia, being the highest point of both. It is located about 130 km (81 mi) west of the capital city Bogotá. It is a stratovolcano composed of many layers of lava alternating with hardened volcanic ash and other pyroclastic rocks. Volcanic activity at Nevado del Ruiz began about two million years ago, during the Early Pleistocene or Late Pliocene, with three major eruptive periods. The current volcanic cone formed during the present eruptive period, which began 150,000 years ago.
The Mono–Inyo Craters are a volcanic chain of craters, domes and lava flows in Mono County, Eastern California. The chain stretches 25 miles (40 km) from the northwest shore of Mono Lake to the south of Mammoth Mountain. The Mono Lake Volcanic Field forms the northernmost part of the chain and consists of two volcanic islands in the lake and one cinder cone volcano on its northwest shore. Most of the Mono Craters, which make up the bulk of the northern part of the Mono–Inyo chain, are phreatic volcanoes that have since been either plugged or over-topped by rhyolite domes and lava flows. The Inyo volcanic chain form much of the southern part of the chain and consist of phreatic explosion pits, and rhyolitic lava flows and domes. The southernmost part of the chain consists of fumaroles and explosion pits on Mammoth Mountain and a set of cinder cones south of the mountain; the latter are called the Red Cones.
Mammoth Mountain Ski Area is a large ski resort in the western United States, located in eastern California along the east side of the Sierra Nevada mountain range in the Inyo National Forest.
Lassen Peak, commonly referred to as Mount Lassen, is a 10,457 ft (3,187 m) lava dome volcano in Lassen Volcanic National Park in Northern California. Located in the Shasta Cascade region above the northern Sacramento Valley, it is the southernmost active volcano in the Cascade Range of the Western United States, and part of the Cascade Volcanic Arc stretching from southwestern British Columbia to northern California. It supports many flora and fauna among its diverse habitats, which reach high elevations and are subject to frequent snowfall.
Mount Katmai is a large active stratovolcano on the Alaska Peninsula in southern Alaska, located within Katmai National Park and Preserve. It is about 6.3 miles (10 km) in diameter with a central lake-filled caldera about two by three miles in size, formed during the Novarupta eruption of 1912. The caldera rim reaches a maximum elevation of 6,716 feet (2,047 m). In 1975 the surface of the crater lake was at an elevation of about 4,220 feet (1,286 m), and the estimated elevation of the caldera floor is about 3,400 ft (1,040 m). The mountain is located in Kodiak Island Borough, very close to its border with Lake and Peninsula Borough. The volcano has caused ten known fatalities due to gas exposure.
The Owens River is a river in eastern California in the United States, approximately 183 miles (295 km) long. It drains into and through the Owens Valley, an arid basin between the eastern slope of the Sierra Nevada and the western faces of the Inyo and White Mountains. The river terminates at the endorheic Owens Lake south of Lone Pine, at the bottom of a 2,600 sq mi (6,700 km2) watershed.
The Poás Volcano, is an active 2,697-metre (8,848 ft) stratovolcano in central Costa Rica and is located within Poas Volcano National Park. It has erupted 40 times since 1828, with a strong eruption on April 2017—causing the evacuation of visitors and residents. The volcano and surrounding park were closed for nearly 17 months, with a 2.5 kilometer safety perimeter established around the erupting crater. On September 1, 2018, the park was reopened to the public only with limited access to the crater observation area. They have started to require a reservation on the National Park Website before visitation. Adjacent trails to Lake Botos, and the museum at the visitor center remained closed. The volcano erupted briefly twice in September 2019.
Inyo National Forest is a United States National Forest covering parts of the eastern Sierra Nevada of California and the White Mountains of California and Nevada. The forest hosts several superlatives, including Mount Whitney, the highest point in the contiguous United States; Boundary Peak, the highest point in Nevada; and the Ancient Bristlecone Pine Forest, which protects the oldest living trees in the world. The forest, encompassing much of the Owens Valley, was established by Theodore Roosevelt as a way of sectioning off land to accommodate the Los Angeles Aqueduct project in 1907, making the Inyo National Forest one of the least wooded forests in the U.S. National Forest system.
Volcanic gases are gases given off by active volcanoes. These include gases trapped in cavities (vesicles) in volcanic rocks, dissolved or dissociated gases in magma and lava, or gases emanating from lava, from volcanic craters or vents. Volcanic gases can also be emitted through groundwater heated by volcanic action.
The Mono Basin is an endorheic drainage basin located east of Yosemite National Park in California and Nevada. It is bordered to the west by the Sierra Nevada, to the east by the Cowtrack Mountains, to the north by the Bodie Hills, and to the south by the north ridge of the Long Valley Caldera.
Mazuku (Swahili for "evil winds") are pockets of dry, cold carbon dioxide-rich gases released from vents or fissures in volcanically and tectonically active areas, and mixed with dispersed atmospheric air and accumulating in typically low-lying areas. Since CO2 is ~1.5 times heavier than air, it tends to flow downhill, hugging the ground like a low fog and gather in enclosed spaces with poor ventilation, such as lava tubes, ditches, depressions, caves, house basements or in the stratified water layers of meromictic lakes if a water column exists. In high concentrations (≥1vol.%), they can pose a deadly risk to both humans and animals in the surrounding area because they are undetectable by olfactory or visual senses in most conditions.
Panum Crater is a volcanic cone that is part of the Mono–Inyo Craters, a chain of recent volcanic cones south of Mono Lake and east of the Sierra Nevada, in California, United States. Panum Crater is between 600 and 700 years old, and it exhibits all of the characteristics of the textbook rhyolitic lava dome.
Hot Creek, starting as Mammoth Creek, is a stream in Mono County of eastern California, in the Western United States. It is within the Inyo National Forest.
The Silverthrone Caldera is a potentially active caldera complex in southwestern British Columbia, Canada, located over 350 kilometres (220 mi) northwest of the city of Vancouver and about 50 kilometres (31 mi) west of Mount Waddington in the Pacific Ranges of the Coast Mountains. The caldera is one of the largest of the few calderas in western Canada, measuring about 30 kilometres (19 mi) long (north-south) and 20 kilometres (12 mi) wide (east-west). Mount Silverthrone, an eroded lava dome on the caldera's northern flank, which is 2,864 metres (9,396 ft) high, may be the highest volcano in Canada.
The California Volcano Observatory (CalVO) is the volcano observatory that monitors the volcanic and geologic activity of California and Nevada. It is a part of the Volcano Hazards Program of the United States Geological Survey, a scientific agency of the United States government.
Horseshoe Lake is a lake in Mono County, California, near the Mammoth Mountain ski resort. The soil near the lake contains a high concentration of carbon dioxide which, when it seeps from the soil, kills trees and poses a threat to humans.
