Images

Geologic time scale showing eras, periods, and notable events in terms of millions of years ago.

A stress vs time graph showing fault strength and an offset across fault vs time graph 

The reflection is the energy or wave from an earthquake that has been returned (reflected) from an boundary between two different materials within the earth, just as a mirror reflects light.

Refraction is (1) the deflection, or bending, of the ray path of a seismic wave caused by its passage from one material to another having different elastic properties. (2) bending of a tsunami wave front owing to variations in the water depth along a coastline.

A P wave, or compressional wave, is a seismic body wave that shakes the ground back and forth in the same direction and the opposite direction as the direction the wave is moving.

Person sitting and overlooking valley of snow-topped mountains with clouds in between mountains 

Diagram of period.  The period is the time interval required for one full cycle of a wave.

Plate Tectonics is the theory supported by a wide range of evidence that considers the earth's crust and upper mantle to be composed of several large, thin, relatively rigid plates that move relative to one another. Slip on faults that define the plate boundaries commonly results in earthquakes.

Ripples on a pond are attenuated as they move away from the source. Q is the inverse of attenuation. A high Q means a low attenuation.

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.

Teleseismic is pertaining to earthquakes at distances greater than 1,000 km from the measurement site.

The time history is the sequence of values of any time-varying quantity (such as a ground motion measurement) measured at a set of fixed times. Also termed time series.

A transform fault is a special variety of strike-slip fault that accommodates relative horizontal slip between other tectonic elements, such as oceanic crustal plates. Often extend from oceanic ridges.

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