A tsunami is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and underwater explosions above or below water all have the potential to generate a tsunami. Unlike normal ocean waves, which are generated by wind, or tides, which are in turn generated by the gravitational pull of the Moon and the Sun, a tsunami is generated by the displacement of water from a large event.
A stratovolcano, also known as a composite volcano, is a 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).
Lake Nyos is a crater lake in the Northwest Region of Cameroon, located about 315 km (196 mi) northwest of Yaoundé, the capital. Nyos is a deep lake high on the flank of an inactive volcano in the Oku volcanic plain along the Cameroon line of volcanic activity. A volcanic dam impounds the lake waters.
A megatsunami is a very large wave created by a large, sudden displacement of material into a body of water.
A seiche is a standing wave in an enclosed or partially enclosed body of water. Seiches and seiche-related phenomena have been observed on lakes, reservoirs, swimming pools, bays, harbors, caves, and seas. The key requirement for formation of a seiche is that the body of water be at least partially bounded, allowing the formation of the standing wave.
A geologic hazard or geohazard is an adverse geologic condition capable of causing widespread damage or loss of property and life. These hazards are geological and environmental conditions and involve long-term or short-term geological processes. Geohazards can be relatively small features, but they can also attain huge dimensions and affect local and regional socio-economics to a large extent.
The Cumbre Vieja is an active volcanic ridge on the island of La Palma in the Canary Islands, Spain. The spine of Cumbre Vieja trends in an approximate north–south direction, comprising the southern half of La Palma, with both summit ridge and flanks pockmarked by dozens of craters and cones. The latest eruption began on 19 September 2021 in a forested area of Las Manchas locality known as Cabeza de Vaca. Voluminous lava flows quickly reached populated areas downslope, fanning out across settlements and banana plantations, destroying thousands of buildings and ultimately pouring over steep cliffs into the ocean to enlarge the island at several locations. The volcano went quiet on 13 December 2021, and on 25 December 2021, the local government declared the eruption to be over.
A limnic eruption, also known as a lake overturn, is a very rare type of natural disaster in which dissolved carbon dioxide suddenly erupts from deep lake waters, forming a gas cloud capable of asphyxiating wildlife, livestock, and humans. Scientists believe earthquakes, volcanic activity, and other explosive events can serve as triggers for limnic eruptions as the rising CO2 displaces water. Lakes in which such activity occurs are referred to as limnically active lakes or exploding lakes. Some features of limnically active lakes include:
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.
Prediction of volcanic activity, and volcanic eruption forecasting, is an interdisciplinary monitoring and research effort to predict the time and severity of a volcano's eruption. Of particular importance is the prediction of hazardous eruptions that could lead to catastrophic loss of life, property, and disruption of human activities.
The Mount Meager massif is a group of volcanic peaks in the Pacific Ranges of the Coast Mountains in southwestern British Columbia, Canada. Part of the Cascade Volcanic Arc of western North America, it is located 150 km (93 mi) north of Vancouver at the northern end of the Pemberton Valley and reaches a maximum elevation of 2,680 m (8,790 ft). The massif is capped by several eroded volcanic edifices, including lava domes, volcanic plugs and overlapping piles of lava flows; these form at least six major summits including Mount Meager which is the second highest of the massif.
There have been known various classifications of landslides. Broad definitions include forms of mass movement that narrower definitions exclude. For example, the McGraw-Hill Encyclopedia of Science and Technology distinguishes the following types of landslides:
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 that is 2,864 metres (9,396 ft) high, may be the highest volcano in Canada.
Submarine landslides are marine landslides that transport sediment across the continental shelf and into the deep ocean. A submarine landslide is initiated when the downwards driving stress exceeds the resisting stress of the seafloor slope material, causing movements along one or more concave to planar rupture surfaces. Submarine landslides take place in a variety of different settings, including planes as low as 1°, and can cause significant damage to both life and property. Recent advances have been made in understanding the nature and processes of submarine landslides through the use of sidescan sonar and other seafloor mapping technology.
The Mount Cayley volcanic field (MCVF) is a remote volcanic zone on the South Coast of British Columbia, Canada, stretching 31 km (19 mi) from the Pemberton Icefield to the Squamish River. It forms a segment of the Garibaldi Volcanic Belt, the Canadian portion of the Cascade Volcanic Arc, which extends from Northern California to southwestern British Columbia. Most of the MCVF volcanoes were formed during periods of volcanism under sheets of glacial ice throughout the last glacial period. These subglacial eruptions formed steep, flat-topped volcanoes and subglacial lava domes, most of which have been entirely exposed by deglaciation. However, at least two volcanoes predate the last glacial period and both are highly eroded. The field gets its name from Mount Cayley, a volcanic peak located at the southern end of the Powder Mountain Icefield. This icefield covers much of the central portion of the volcanic field and is one of the several glacial fields in the Pacific Ranges of the Coast Mountains.
The island of La Palma in the Canary Islands is at risk of undergoing a large landslide, which could cause a tsunami in the Atlantic Ocean. Volcanic islands and volcanoes on land frequently undergo large landslides/collapses, which have been documented in Hawaii for example. A recent example is Anak Krakatau, which collapsed to cause the 2018 Sunda Strait tsunami.
On the morning of March 13, 1888, an explosion took place on Ritter Island, a small volcanic island in the Bismarck and Solomon Seas, between New Britain and Umboi Island. The explosion resulted in the collapse of most of the island and generated a tsunami with runups of up to 15 meters (49 ft) that caused damage more than 700 kilometers (430 mi) away and killed anywhere between 500 and 3,000 on neighboring islands, including scientists and explorers. This event is the largest volcanic island sector collapse in recent history.
A volcanic tsunami, also called a volcanogenic tsunami, is a tsunami produced by volcanic phenomena. About 20–25% of all fatalities at volcanoes during the past 250 years have been caused by volcanic tsunamis. The most devastating volcanic tsunami in recorded history was that produced by the 1883 eruption of Krakatoa. The waves reached heights of 40 m (130 ft) and killed 36,000 people.
The 1840 Ahora earthquake occurred on 2 July at 16:00 local time, affecting Ağrı Province in the Eastern Anatolia Region of present-day Turkey. The earthquake had an epicenter near Mount Ararat, where it triggered an eruption and caused a landslide that destroyed villages. An estimated 10,000 people were killed by the earthquake and its damaging aftershocks. Earthquake catalogs place the surface-wave magnitude at Ms 7.4 and maximum Modified Mercalli intensity scale assigned IX (Violent).
A volcanic landslide or volcanogenic landslide is a type of mass wasting that takes place at volcanoes.
