EAS 10600

Scientific Method Steps

1) Observation, 2) Hypothesis, 3) Prediction, 4) Testing, 5) Continual reexamination.

Divergent Boundary

Plates pull apart, generating new crust and causing rifting/spreading.

Convergent Boundary

Plates collide and crust is destroyed as a denser plate subducts, forming trenches/volcanoes.

Transform Boundary

Plates slide horizontally past each other; crust is neither produced nor destroyed.

Mafic

Low-silica composition; rich in iron/magnesium, low viscosity, creates fluid lava flows.

Felsic

High-silica composition; rich in potassium/sodium, high viscosity, creates explosive eruptions.

Ultramafic

Extremely high iron/magnesium composition that makes up the Earth's mantle.

Mt. St. Helens

Washington stratovolcano; 1980 earthquake triggered a landslide and deadly lateral blast.

Mt. Fuji

Japanese stratovolcano; last erupted in 1707.

Mt. Rainier

Washington stratovolcano; last erupted 2,200 years ago.

Volcano

A vent from which magma, solid rock debris, and gases are erupted.

Viscosity

Resistance to flow; heavily dependent on silica content (higher silica = higher viscosity).

Magma

Molten rock, suspended minerals, and dissolved gases inside the Earth.

Lava

Magma that successfully reaches the Earth's surface.

Volatiles

Dissolved gases (mostly water vapor/CO2) in magma that form bubbles and cause explosions.

Basalt

Fine-grained, extrusive igneous rock formed from mafic magma (makes up oceanic crust).

Rhyolite

Fine-grained, extrusive igneous rock formed from highly viscous, felsic magma (explosive).

Andesite

Fine-grained, extrusive igneous rock formed from intermediate magma (common at subduction zones).

Elastic Rebound Theory

Rocks bend/store energy along a fault until friction is overcome, releasing energy as seismic waves.

Earthquake

Intense ground shaking caused by the sudden release of stored elastic energy along a slipping fault.

San Francisco Earthquake 1906

Major San Andreas fault slip; over 90% of structural damage was actually caused by fire.

China earthquakes 1970's

1975 Haicheng quake was successfully predicted; 1976 Tangshan quake was not, killing >250,000.

Japanese Earthquake 2011

Mag 9.0 subduction quake; a massive resulting tsunami caused 90% of the casualties.

Haitian Earthquake 2010

(Not detailed in the provided lecture slides)

Turkish Earthquakes 2023

Mag 7.8 and 7.5 quakes along the East Anatolian Fault caused by plate squeezing; 60,000 deaths.

Epicenter

The point on the Earth's surface directly above the focus.

Focus

The exact point or region inside the Earth where earthquake energy is first released.

Seismic Zone

Deep, active areas of earthquake activity (e.g., Benioff zones at subduction margins).

Layers of the earth

Divided into Compositional (Crust, Mantle, Core) and Structural (rigid Lithosphere, flowing Asthenosphere). The Core has a liquid outer and solid inner layer.

Seismic Waves

Energy traveling through Earth: Body Waves (P/S-waves inside) and Surface Waves (Love/Rayleigh waves).