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27 Cards in this Set
- Front
- Back
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Earthquake |
The sudden release of elastic energy when a rock breaks (deformations in the rock will store this energy). |
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Deep earthquakes |
In the Wadati-Benioff zone (around rims of oceans); occur in colder, subducted crust) |
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Focus |
Where the earthquake actually originated |
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Epicenter |
the point on the surface directly about the focus |
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Richter scale |
measures amplitudes of seismic waves on a seismogram; based on the maximum recorded amplitude |
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Earthquake intensity |
strength of the ground shaking at a point |
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Body waves |
Primary (P) waves Secondary (S) waves |
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Primary (P) waves |
First to arrive. Compressional waves (compresses particles). Passes through solid, liquids, gasses. |
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Secondary (S) waves |
AKA Shear waves. Causes shape change to the rock. Only move through solids |
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Surface waves |
When body waves reach the surface. Slower but larger than body waves. |
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Types of surface waves (2) |
Rayleigh waves: up and down Love waves: side to side (formed by S waves hitting the surface) |
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Locating earthquakes |
Find the distance from the focus by comparing when the P and S waves arrive |
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Hazards associated with earthquakes (6) |
1. Liquefaction: solids turn to liquids below buildings 2. Destroyed infrastructure 3. Landslides 4. Land subsidence/uplift 5. Fire 6. Tsunamis (likely the most dangerous) |
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Earthquakes tell us about Earth's core ... |
P-waves can be reflected/refracted; heavily refracted by earth's core, meaning there is a composition change. When S waves are blocked, there is a change of state (no longer solid) Moho: boundary between crust and upper most mantle has several transitions |
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Volcano |
A vent or fissure from which melted/solid rock and gas erupted |
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Volcanic settings |
Hot spots (under oceans and continents), divergent boundaries, mid-ocean ridges, rifts in continent, subduction and collision zones ... basically anywhere magma is being produced and path for it to get to the surface |
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Molten rock ... |
Underground = magma Surface = lava |
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Igneous rocks classified by where they solidified |
Underground = plutonic or intrusive (coarser grained, slower cooling) Aboveground = volcanic or extrusive (finer grained, faster cooling) |
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Silica content classifies igneous rocks (3) |
1. Mafic: ~50% silicate, dark, formed by partial melting of mantle, low viscosity 2. Intermediate: 50-70% silicate, formed at subduction zones, intermediate properties 3. Felsic: >70% silicate, light, melt at low temperatures, high viscosity |
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Partial melting |
Rocks are made up of different materials therefore melt at different temps, so the magma can have different composition than the rock it is melting |
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Fractional crystallization |
creates different types of igneous rocks, blocks the magma chambers |
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Different magma type produced by igneous setting |
Basalt: ocean hot spots, mid ocean ridges Intermediate: subduction zones Felsic: continental hotspot |
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Mafic magmas |
Low silicates so low viscosity, gases escape easily, quiet eruptions (lava flows). Tend to form shield volcanoes |
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Fissure eruptions |
Flood basalt. Cover huge areas. Can have continuous eruptions (forming mid ocean ridges) |
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Felsic/intermediate magmas |
High silicates so high viscosity. Gasses do not escape easily. Explosive eruptions with lots of tephra. Cause stratovolcanoes (the "classic") |
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Rhyolite Caldera Complexes (Calderas) |
Large holes in the ground (usually lakes) with a volcano in the middle. Usually cause a lot of steam (due to heat of the magma plus the surrounding water) |
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Hazards of eruptions (7) |
1. Lava flows (limited to fluid magma, small problem) 2. Tephra fall (limited to explosive eruptions. Hazard to planes, respiration, mass loading, short term climate affects) 3. Pyroclastic flows (fluidized masses of rock fragments and gasses that move VERY fast due to gravity, from explosive eruptions) 4. Mudflows (debris composed of pyroclastic material, rock, water; very thick. AKA lahars. Need a water source) 5. Tsnuamis 6. Gas emissions 7. Climate change (short and long term, balance CO2 levels in the atmosphere) |
