Volcano and Earthquake Flashcards
A volcano is an…
Opening in the earth’s crust through which lava, volcanic ash, and gases escape.
There are 3 types of volcanoes are…
Active volcano, Dormant volcano, Extinct volcano
Volcanic eruptions are partly driven by pressure from…
Beneath a volcano, …… containing dissolved gases rises through cracks in the Earth’s crust.
- Dissolved Gas
- Liquid magma
Viscosity is…
A measure of how thick (viscous) and sticky a liquid is
Three types of Volcanoes:
– Cinder: explosive eruptions, small but steep slopes, pyroclastics.
– Shield: non-explosive eruptions, fluid basaltic lava, gentle broad slopes.
– Composite: alternating between lava and pyroclastics, explosive and non-explosive eruptions, steep and tall.
Effusive Eruptions:
Generally at hots spots, spreading centers
Mantle comes directly to surface
Hot lava; low viscosity, very mafic, flows easily, gases escape easily
Forms shields, flood basalts
Explosive Eruptions:
Found at subduction zones
Magma low temp (800 degrees C), high viscosity, does not flow easilty, more felsic mineralogy, gases trapped, hard to predict explosions
Forms composite volcanoes, cinder cones, calderas, aerial bombs, nuee ardente gas flows, very destructive
An earthquake is…
A sudden slipping or movement or shaking of a portion of the earth’s crust caused by a release of energy
A fault is…
A break in the lithosphere along which movement has occurred
The focus of an earthquake is…
The point at which movement first occurs
The epicenter of an earthquake is…
The point on the surface of the earth directly above the focus
An aftershock is…
An earthquake of less intensity that follows the main earthquake
Seismic waves are…
Waves that transmit the energy released by and earthquake
Why do earthquakes occur?
Fractures, faults
Energy released and propagates in all directions as seismic waves causing earthquakes
Where do earthquakes occur?
1) Most earthquakes occur along the edge of the oceanic and continental plate
2) Along faults: normal, reverse, strike-slip
