Earthquake Magnitudes, Subduction Zones, and Tsunamis

Vocabulary flashcards covering earthquake magnitude determinants, famous subduction zone megathrust events, and tsunami generation mechanisms from Chapter 1 to 5.

Rupture area

A key factor controlling earthquake magnitude defined by how long a fault breaks and how deep the rupture extends into the Earth's crust.

Fault slip

The distance or amount that two sides of a fault move past each other during an earthquake.

Rock rigidity

Also referred to as rock stiffness, this property controls the amount of elastic energy that can build up before a fault breaks.

Wilson Coversmith

Researchers associated with empirical relations that relate earthquake magnitude to rupture length, rupture area, and rupture dimensions.

San Andreas Fault

A right-lateral strike-slip transform fault approximately $750\,\text{miles}$ long that is incapable of producing a magnitude $9.0$ or greater earthquake due to its fault geometry.

2011 Japan Earthquake

A magnitude $9.0$ earthquake occurring in March 2011 offshore along the Japan Trench, caused by subduction of the Pacific plate beneath Japan.

1964 Great Alaska Earthquake

A magnitude $9.2$ earthquake occurring in Prince William Sound, recognized as the largest earthquake ever recorded in the United States and the second largest in history.

George Placker

The USGS geologist who applied the newly forming theory of plate tectonics to explain the 1964 Alaska earthquake as a megathrust earthquake.

Megathrust earthquake

A powerful earthquake produced by periodic slip along the low-angle interface where an oceanic plate subducts beneath an overriding continental plate.

2004 Sumatra Earthquake

A massive subduction earthquake caused by the India plate subducting, where the fault rupture spread northward sequentially like a zipper.

Thrust fault

A shallow-angle reverse fault where the overlying plate thrusts up over the subducting plate during convergent plate movement.

Splay faulting

A phenomenon where displacement branches into steeply dipping faults off the main megathrust fault, causing concentrated ocean floor uplift and generating rapid, large tsunamis.

Patton Bay Fault

A splay fault involved in the 1964 Alaska earthquake that experienced $9\,\text{meters}$ of displacement, causing localized uplift of the continental shelf.