Hazard Progression Flashcards
Loess
A loosely compacted yellowish-grey deposit of wind-blown sediment of which extensive deposits occur. An example would be American Midwest.
Pyroclastic Flow
A dense, destructive mass of very hot ash, lava fragments, and gases ejected explosively from a volcano and typically flowing at great speed.
After Shocks
A smaller earthquake following the main shock of a large earthquake.
Cloud Seeding
The dropping of crystals into clouds to cause rain.
Crater
A bowl-shaped geological formation at the top of a volcano. A large crater caused by the violent explosion of a volcano that collapses into a depression.
Dyke
A sheet of rock that formed in a fracture in a pre-existing rock body. … Magmatic dikes form when magma intrudes into a crack then crystallizes as a sheet intrusion, either cutting across layers of rock or through an unlayered mass of rock.
Intrusive Volcanic Features
When magma is forced to the surface only a small amount of the mass actually reaches that level. Most of the magma is intruded into the crust where it solidifies into a range of features. These are often exposed at the surface by later erosion.
Extrusive Volcanic Features
When volcanic activity takes place above ground, so that hot molten magma is released onto the landscape, we say that the volcanic activity is extrusive, meaning it is on the exterior, or outside of the Earth. Magma that reaches the service is known as lava. Lava flows are extraordinarily hot, and destructive.
Liquefaction
Soil liquefaction describes a phenomenon whereby a saturated or partially saturated loses strength and stiffness in response to a stress, usually earthquake shaking, causing it to behave like a liquid.
Mudslide
A mass of mud and other earthy material that is falling or has fallen down a hillside or other slope.
Plug
A volcanic object created when magma hardens within a vent on an active volcano. When present, a plug can cause an extreme build-up of pressure if rising volatile-charged magma is trapped beneath it, and this can sometimes lead to an explosive eruption.
Parasitic Cone
The cone-shaped accumulation of volcanic material not part of the central vent of a volcano. It forms from eruptions from fractures on the flank of the volcano. These fractures occur because the flank of the volcano is unstable.
Rift Valley
A steep-sided valley formed by the downward displacement of a block of the earth’s surface between nearly parallel faults or fault systems.
Secondary Hazard
Due to the occurrence of another (primary) hazard.
Shockwave
A widespread feeling of shock caused by an unexpected event.
