Velocity
How fast a point on the ground is shaking as a result of an earthquake.
Vent
The opening at the earth’s surface through which volcanic materials issue forth.
Viscosity
A measure of resistance to flow in a liquid
Volcanic Arc
A curved chain of volcanic islands (such as the Lesser Antilles) or volcanic mountains (such as the Andes) located near the margins of two plates that has formed due to magmatism at a subduction zone
Volcanic Complex
An area made up of several vents and associated volcanic features.
Volcanic earthquake
An earthquake characterized by high-frequency seismic signals thought to be generated by the fracturing of rock in response to the intrusion and migration of magma.
Volcanic eruption
The arrival of volcanic products at the surface of the earth during a single volcanic event or, if clearly linked, a series of volcanic events (e.g. the activity at the Soufrière Hills volcano
since 1995 is considered a single eruption). Eruptions can be explosive or effusive, depending on the physical properties of the magma.
Volcanic gases
Magma contains dissolved gases that are released into the atmosphere during eruptions. In addition, geothermal systems and areas of cold spring activity also emit large amounts of gases.
The most common gases in volcanic areas are water vapour (H2O), carbon dioxide (CO2) and sulphur dioxide (SO2) with smaller amounts of hydrogen sulphide (H2S), carbon monoxide
(CO), hydrogen chloride (HCl) and hydrogen fluoride (HF).
Volcanic hazard
Volcanic hazard is the probability of a given area being affected by potentially destructive volcanic processes or products within a given period of time.
Volcano
A volcano is a vent in the Earth’s surface where magma and associated gases erupt. The style of eruption and type of volcano depend on the properties and volume of the magma as well as external factors such as crustal structure and presence of groundwater or geothermal systems.
Volcanology
The study of the generation and movement of molten rock on Earth and other planetary bodies, primarily through volcanoes and volcanic eruptions.
Volcanologist
Scientist who studies volcanos and its associated features and hazards.
Vulcanian eruption
An explosive eruption of less than 1 km3, but with an eruption column often reaching 10-20 km high.
