Geology: Plate Tectonics and Earthquake Characteristics

Vocabulary flashcards covering earthquake depth categories, lithosphere characteristics, mid-ocean ridge processes, and spreading rate calculations.

Glassblower Logic

A foundational concept used to determine earthquake power, stating that hot material bends easily (resulting in weak earthquakes), while cold, brittle material snaps hard (resulting in powerful earthquakes).

Earthquake

An event that occurs when the Earth breaks, commonly where tectonic plates touch and move past or away from each other.

Shallow Earthquake

An earthquake defined as occurring between $0$ and $100\,\text{km}$ below the Earth's surface.

Intermediate Depth Earthquake

An earthquake defined as occurring between $100$ and $400\,\text{km}$ below the Earth's surface.

Deep Earthquake

An earthquake defined as occurring at depths greater than $400\,\text{km}$ below the Earth's surface.

Lithosphere

The rigid, breakable outer layer of the Earth composed of all the crust and part of the uppermost mantle.

Oceanic Lithosphere Thickness

The thickness range of oceanic lithosphere, defined as being between $0$ and $70\,\text{km}$ thick.

Mid-Oceanic Ridge Earthquake Signature

Earthquakes occurring at ocean-ocean divergent plate boundaries, characterized as weak (because active volcanism makes the rock hot and bendy) and shallow only (because oceanic lithosphere is maximum $70\,\text{km}$ thick).

Thingvellir

A national park in Iceland situated directly on the Mid-Atlantic Ridge where the North American plate and Eurasian plate can be seen pulling apart above sea level.

Black Smokers

Hydrothermal vents at mid-ocean ridges where superheated water carrying sulfur and metals precipitates mineral crystals and supports chemosynthetic life independent of sunlight.

Atlantic Spreading Rate

The rate at which North America and Africa are moving away from each other, calculated as $4.4\,\text{cm/yr}$ based on a separation distance of $7{,}000\,\text{km}$ over $160{,}000{,}000\,\text{years}$.