Earthquake
It is a term used to describe both the sudden movement along a fault and the energy released from the movement caused and the resulting ground shaking. Volcanic or magmatic activity, landslides and/or other sudden stress changes in the earth can also cause it.
Earthquake hazard
It is anything associated with an earthquake that may affect the normal activities of people. This includes but is not limited to ground shaking, surface faulting, landslides, fires, liquefaction, tsunamis and deformation.
Earthquake risk
It is the probable damage, and number of people that are expected to be hurt or killed if a likely earthquake occurs in a particular area. It is often incorrectly used interchangeably with earthquake hazard.
Earthquake swarm
A group of many shallow earthquakes of similar size occurring closely clustered in space and time with no dominant main shock. Earthquake swarms may indicate that magma is moving beneath a volcano, and often precede volcanic eruptions in the Lesser Antilles.
Effusive eruption
Effusive eruptions occur when molten rock (magma) reaches the Earth’s surface and erupts passively, producing lava flows and lava domes. They generally occur when the gas content of the magma is low. Basaltic magmas tend to erupt effusively and produce lava flows.
Ejecta
Material that is erupted/thrown out by a volcano during an eruption. This includes tephra and bombs.
Epicentre
Is the point of the surface vertically above the hypocenter (focus).
Eruption
The process by which solid, liquid, and gaseous materials are ejected into the earth’s atmosphere and onto the earth’s surface by volcanic activity.
Eruption column
A turbulent, buoyant mixture of hot volcanic particles and gases ejected explosively from a volcano
Eruption column collapse
The collapse of an eruption column occurs when the density of the volcanic particles entrained in the column exceeds the upward buoyancy of the column. The volcanic particles fall back down to the ground under the influence of gravity and can form pyroclastic flow, surge and fall deposits.
Eruption Cloud
The column of gases, ash and other ejecta rising from a volcanic crater or another vent. If it reaches a certain volume and height, this column may reach many miles into the stratosphere and the material can travel long distances on air current and can even circumnavigate the planet. .
Estimated time of arrival (ETA) (Tsunamis)
Time of tsunami arrival at some fixed location, as estimated from modelling the speed and refraction of the tsunami waves as they travel from the source. ETA is estimated with very good precision if the bathymetry and source are well known (less than a couple of minutes). The first wave is not necessarily the largest, but it is usually one of the first five waves.
Extinct
A volcano that is not presently erupting, has not erupted in the last 10,000 years and is not likely to do so for a very long time in the future.
Extrusion
The secretion of magmatic material at the Earth’s surface. It can also refer to the structure or form produced by a lava flow, a dome or pyroclastic rocks.
Explosive eruption
An explosive eruption involves the rapid expansion of gas causing the surrounding rock or magma to fragment explosively. There are 3 types of explosive eruptions.
Evacuation map
A drawing or representation that outlines danger zones and designates limits beyond which people must be evacuated to avoid harm from tsunami waves. Evacuation routes are sometimes designated to ensure the efficient movement of people out of the evacuation zone to evacuation shelters.
