Liquefaction is a process by which water-saturated sediment temporarily loses strength and acts like a fluid... like when you wiggle your toes in the wet sand near the water at the beach. This effect can be caused by earthquake shaking.
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Liquefaction
Liquefaction is a process by which water-saturated sediment temporarily loses strength and acts like a fluid... like when you wiggle your toes in the wet sand near the water at the beach. This effect can be caused by earthquake shaking.
Normal Fault
Normal, or Dip-slip, faults are inclined fractures where the blocks have mostly shifted vertically. If the rock mass above an inclined fault moves down, the fault is termed normal, whereas if the rock above the fault moves up, the fault is termed a Reverse fault.
Normal, or Dip-slip, faults are inclined fractures where the blocks have mostly shifted vertically. If the rock mass above an inclined fault moves down, the fault is termed normal, whereas if the rock above the fault moves up, the fault is termed a Reverse fault.
Shadow Zone
The shadow zone is the area of the earth from angular distances of 104 to 140 degrees that, for a given earthquake, that does not receive any direct P waves. The shadow zone results from S waves (not shown in animation) being stopped entirely by the liquid core and P waves being bent (refracted) by the liquid core.
The shadow zone is the area of the earth from angular distances of 104 to 140 degrees that, for a given earthquake, that does not receive any direct P waves. The shadow zone results from S waves (not shown in animation) being stopped entirely by the liquid core and P waves being bent (refracted) by the liquid core.
Strike-Slip Fault
Strike-slip faults are vertical (or nearly vertical) fractures where the blocks have mostly moved horizontally. If the block opposite an observer looking across the fault moves to the right, the slip style is termed right-lateral; if the block moves to the left, the motion is termed left-lateral.
Strike-slip faults are vertical (or nearly vertical) fractures where the blocks have mostly moved horizontally. If the block opposite an observer looking across the fault moves to the right, the slip style is termed right-lateral; if the block moves to the left, the motion is termed left-lateral.
Thrust Fault
A thrust fault is a reverse fault with a dip of 45° or less, a very low angle. This animation shows a reverse fault which is a steeper-angle fault, but it moves the same way.
A thrust fault is a reverse fault with a dip of 45° or less, a very low angle. This animation shows a reverse fault which is a steeper-angle fault, but it moves the same way.
Wavefront
The wavefront is the instantaneous boundary between the seismic waves in the earth material, and the material that the seismic energy has not yet reached. As a seismic wave propagates through the earth, the wavefront moves.
The wavefront is the instantaneous boundary between the seismic waves in the earth material, and the material that the seismic energy has not yet reached. As a seismic wave propagates through the earth, the wavefront moves.
Great Circle
The shortest path between two points on the surface of a sphere lies along a great circle. On a 2-dimensional map, this looks like a line, but when it's on a 3-dimensional sphere, it's an arc... part of a circle.
The shortest path between two points on the surface of a sphere lies along a great circle. On a 2-dimensional map, this looks like a line, but when it's on a 3-dimensional sphere, it's an arc... part of a circle.
PubTalk 4/2011 - Predictable Earthquakes
Title: Predictable Earthquakes - updating earthquake prediction - fact vs. fiction
Title: Predictable Earthquakes - updating earthquake prediction - fact vs. fiction
Preparedness Now
This film depicts the realistic outcome of a hypothetical, but plausible, magnitude 7.8 earthquake on the San Andreas fault in Southern CA.
This film depicts the realistic outcome of a hypothetical, but plausible, magnitude 7.8 earthquake on the San Andreas fault in Southern CA.
Preparedness Now
This film takes you on a visceral journey through the USGS ShakeOut Earthquake Scenario.
This film takes you on a visceral journey through the USGS ShakeOut Earthquake Scenario.
PubTalk — Earthquakes at the USGS
Blowing the Lid off Seismic Science for 40 Years
Ross Stein, representing the USGS Earthquake Hazards Team
Blowing the Lid off Seismic Science for 40 Years
Ross Stein, representing the USGS Earthquake Hazards Team
PubTalk 6/2003 — The Quakes, They Are A-comin'
New Estimates of Earthquake Hazard and Risk Across the Bay Region
By Michael Blanpied, Geophysicist
New Estimates of Earthquake Hazard and Risk Across the Bay Region
By Michael Blanpied, Geophysicist
PubTalk 10/2002 — Plumbing the Mysteries of the San Andreas Fault
Deep Drilling to Test Fundamental Theories About Faulting and Earthquakes
By Stephen H. Hickman, Geophysicist
Deep Drilling to Test Fundamental Theories About Faulting and Earthquakes
By Stephen H. Hickman, Geophysicist
PubTalk 6/2002 — Finding Elusive Earthquake Faults
New Mapping Techniques Reveal Potential Seismic Sources Beneath Seattle
By Richard J. Blakely, Geophysicist and Ralph A. Haugerud, Geologist
New Mapping Techniques Reveal Potential Seismic Sources Beneath Seattle
By Richard J. Blakely, Geophysicist and Ralph A. Haugerud, Geologist