Images

Cable Canyon was burned during the Grand Prix-Old Fire of 2003 and experienced debris flows and floods in response to the December 25, 2003 rainstorm. Two people lost their lives at this site.

USGS and university geologists study the walls of a trench across a recently discovered strand of the Seattle fault.

The Landers fault (red lines at left) and the Hector Mine fault and its aftershocks (red lines and circles at right). The Hector Mine earthquake was a magnitude 7.1, and it produced thousands of aftershocks. 

Fault surface trace of the Hector Mine fault after the October 16, 1999 M7.1 rupture. (Photo by Katherine Kendrick, U.S. Geological Survey)

Hector Mine surface rupture after 1999 earthquake in southern California. 

Photograph showing a house that was damaged by a 1997 landslide along Perkins Lane in Seattle, Washington.

Predicted Spectral Accelerations by the Youngs et al. (1997) Attenuation Relationship 

Photograph showing the scar left by a landslide on a hillside above the Burlington Northern Santa Fe Railway in Everett, Washington.

The "Ring of Fire", also called the Circum-Pacific belt, is the zone of earthquakes surrounding the Pacific Ocean- about 90% of the world's earthquakes occur there. The next most seismic region (5-6% of earthquakes) is the Alpide belt (extends from Mediterranean region, eastward through Turkey, Iran, and northern India.

An oceanic spreading ridge is the fracture zone along the ocean bottom where molten mantle material comes to the surface, thus creating new crust. This fracture can be seen beneath the ocean as a line of ridges that form as molten rock reaches the ocean bottom and solidifies.

Seismicity of the United States 1975-1995. Seismicity refers to the geographic and historical distribution of earthquakes.

This ShakeMap of the January 17, 1994 M6.7 Northridge earthquake shaking shows the result of rupture directivity toward the north.

The Emerson fault, one of the segments that ruptured in the M7.2 1992 Landers, Calfornia earthquake. 

1992 M7.2 Landers, California earthquake slip model

A slip model is a kinematic model that describes the amount, distribution, and timing of slip associated with an earthquake.

Cross-Sections of Seismicity Along the San Andreas Fault from "Lessons learned from the Loma Prieta, California, earthquake of October 17, 1989"

The segments of the San Andreas Fault, and the probability for strong shaking in the next 30 years on each segment. 

The Mameyes, Puerto Rico, landslide, 1985. This landslide destroyed 120 houses and killed at least 129 people. The catastrophic slide was triggered by a tropical storm that produced extremely heavy rainfall.

The April 1983 landslide at Thistle, Utah, created a 200-ft-high (60-m-high) blockage of Spanish Fork canyon that caused disastrous flooding of the Thistle creek and Soldier Creek valleys upstream.  The flooding caused by the landslide required relocation of a major highway and railway.  An emergency spillway and diversion tunnels were constructed to drain

During the first week of April a different type of seismic signature was showing up on seismograms from Mount St. Helens. On April 1 the first weak harmonic tremor was detected. Stronger bursts of harmonic tremor were recorded on the 2nd. The seismogram above is an example of harmonic tremor recorded at seismic station RAN on April 2.

The nine generalized couples of the seismic moment tensor. Modified after Aki and Richards (1980).

Photo of deformed rock. Deformation is a change in the original shape of a material. When we are talking about earthquakes, deformation is due to stress and strain.