Images

Photo of a Kinemetrics FBA-23 accelerograph. The device is black and square with rounded edges on a green background.

This image of the Los Angeles region combines this information to predict the total amplification expected in future earthquakes from local geologic conditions or site effects.

A diagram depicting the tectonic components of a volcanic arc, including the back arc spreading center, back arc convection cell, zone of fractional melting, outer arc trough, outer arc ridge, subducting oceanic lithosphere, and asthenosphere.

An illustration depicting an asperity (pink blob) on fault surface (yellow parallelogram). 

A diagram showing a slice of the Earth's lithosphere, including continental crust, oceanic crust, asthenosphere, and the upper mantle.

An illustration showing two stick figures doing basement excavations, one with a frown that excavated into the labelled hard, stable bedrock on the left and the other with a smile that excavated above the labelled bedrock surface.  

Cross-section of the Benioff zone resulting from a by the interaction of a downgoing oceanic crustal plate with a continental plate.

A diagram of a blind thrust fault resulting in ductile rock layers folding over the fault and leaving the fault under the surface.

A sketch of the thinner crust and thicker mantle. The crust and top portion of the mantle are labelled "Lithosphere "strong'" and the bottom portion of the mantle (bottom) labelled "Asthenosphere "weak.'" 

A diagram with 3 yellow squares with arrows pointing to indicate steps. The first step is labelled "Time 1: pure parent isotope," the second step is labelled "After 1 half life: 1/2 parent and 1/2 daughter isotope," and the third step is labelled "After 2 half lives: 1/4 parent and 3/4 daughter isotopes." 

A traveltime curve is a graph of arrival times, commonly P or S waves, recorded at different points as a function of distance from the seismic source. Seismic velocities within the earth can be computed from the slopes of the resulting curves. 

A tsunami is a sea wave of local or distant origin that results from large-scale seafloor displacements associated with large earthquakes, major submarine slides, or exploding volcanic islands.

Tsunamigenic is referring to those earthquakes, commonly along major subduction zone plate boundaries such as those bordering the Pacific Ocean, that can generate tsunamis.

Turbidites (interbedded with mudstones/siltstones) from the Ross Sandstone Formation Turbidite system of Namurian age in County Clare, Western Ireland. The sandstone beds were formed in a deep basin by turbidites coming from a delta area.

A velocity structure is a generalized regional model of the earth's crust that represents crustal structure using layers having different assumed seismic velocities.

YBP is an abbreviation for "years before present".

Formation of Earth: 4.6x10^9 YBP

Dinosaur extinction: 6.5x10^7 YBP

First hominids: 2x10^6 YBP

Last great ice age: 1x10^4 YBP

Declaration of Independence: 2x10^2 YBP

Establishment of UWB: 1x10 YBP

High, medium, and low amplitude. The amplitude is the size of the wiggles on an earthquake recording.

Ripples on a pond are attenuated as they move away from the source. When you throw a pebble in a pond, it makes waves on the surface that move out from the place where the pebble entered the water. The waves are largest where they are formed and gradually get smaller as they move away. This decrease in size, or amplitude, of the waves is called attenuation.

A seismic refraction or seismic reflection line is a set of seismographs usually lined up along the earth's surface to record seismic waves generated by an explosion for the purpose of recording reflections and refractions of these waves from velocity discontinuities within the earth. The data collected can be used to infer the internal structure of the earth.

The residual is the difference between the measured and predicted values of some quantity.

If you were to stand on the fault and look along its length, this is a type of strike-slip fault where the right block moves toward you and the left block moves away.