Why are there so many faults in the Quaternary Faults Database with the same name?

Many faults are mapped as individual segments across an area.  These fault segments are given a different value for name, number, code, or dip direction and so in the database each segment occurs as its own unique entity.  For example, the San Andreas Fault has several fault segments, from letters a to h, and fault segment 1h has segments with age of last fault movement from historic (<150 years) to late Quaternary (<13,000 years), with dip direction from vertical to unspecified, and fault type from exposed to concealed.

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Where are the fault lines in the Eastern United States (east of the Rocky Mountains)?

Faults are different from fault lines. A fault is a three-dimensional surface within the planet Earth. At the fault, rocks have broken. The rocks on one side of the fault have moved past the rocks on the other side. In contrast, a fault line is a line that stretches along the ground. The fault line is where the three-dimensional fault intersects...

Why are there no faults in the Great Valley of central California?

The Great Valley is a basin, initially forming some ~100 million years ago as a low area between the subducting ocean plate on the west (diving down under the North American plate) and the volcanoes to the east (now the Sierra Nevada mountains). Since its formation, the Great Valley has continued to be low in elevation. Starting about 15 million...

Why are there so many earthquakes and faults in the Western United States?

This region of the United States has been tectonically active since the supercontinent Pangea broke up roughly 200 million years ago, and in large part because it is close to the western boundary of the North American plate. Since the formation of the San Andreas Fault system 25-30 million years ago, the juxtaposition of the Pacific and North...

What is a "Quaternary" fault?

A Quaternary fault is one that has been recognized at the surface and that has moved in the past 1,600,000 years, a portion of the Quaternary epoch.

Where can I find a fault map of the United States? Is one available in GIS format?

An online map of U.S. Quaternary Faults (faults that have been active in the last 1.6 million years) is available via the Quaternary Fault and Fold Database . There is an interactive map application to view the faults online and a seperate database search function. KML (Google Earth-type) files and GIS shape files are also available for download...

I am looking to buy land near the location of a large historical earthquake. I am wondering where the fault line runs. What is the seismic activity in the area today? How did the quake change the contours and elevations of the area?

You will have to research this yourself in journals, books, or online. A good general reference book is USGS Professional Paper 1527 (published 1993): Seismicity of the United States, 1568-1989 (Revised) . Earthquakes that occurred prior to 1990 should be described in the Professional Paper along with other historical earthquakes in the vicinity...

How do I find fault or hazard maps for California?

An online map of faults that includes California can be found in the Faults section of the Earthquake Hazards Program website. Choose the Interactive Fault Map, or download KML files and GIS shapefiles from the links on the page. USGS seismic hazard maps, data and tools for California and other parts of the United States can be found in the...

What is a fault and what are the different types?

A fault is a fracture or zone of fractures between two blocks of rock. Faults allow the blocks to move relative to each other. This movement may occur rapidly, in the form of an earthquake - or may occur slowly, in the form of creep . Faults may range in length from a few millimeters to thousands of kilometers. Most faults produce repeated...

What is the relationship between faults and earthquakes?  What happens to a fault when an earthquake occurs?

Earthquakes occur on faults - strike-slip earthquakes occur on strike-slip faults, normal earthquakes occur on normal faults , and thrust earthquakes occur on thrust or reverse faults. When an earthquake occurs on one of these faults, the rock on one side of the fault slips with respect to the other. The fault surface can be vertical, horizontal,...
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Date published: April 20, 2006

New USGS Maps Show San Francisco Bay Area's Active Faults and Underlying Geologic Deposits

The U.S. Geological Survey (USGS) is releasing two new maps providing a new look at the hazards and geologic history of the greater San Francisco Bay Area.

Date published: April 17, 2006

New Maps Show Active Earthquake Faults and Geologic Complexity of Bay Area

 

The U.S. Geological Survey (USGS) will release new maps of active faults in the Bay Area and the complex geology that underlays the region during the 1906 Earthquake Centennial Conference in San Francisco. Acting USGS Director Patrick Leahy will participate in the news briefing.

Date published: March 9, 2006

A Virtual Tour of the Hayward Fault

The U.S. Geological Survey has a new website that offers a virtual tour of the Hayward fault.

Date published: June 7, 2004

USGS Releases Quaternary Fault Database for the Nation

What are the faults in my state and where are they? When did they last have an earthquake? Now you can find out the answer to these questions online through a user-friendly interface developed by the USGS.

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Faults and earthquakes recorded from the Monterey Peninsula to Pigeon Point
April 14, 2016

Faults and earthquakes recorded from the Monterey Peninsula to Pigeon Point

Faults and earthquakes recorded from the Monterey Peninsula to Pigeon Point — Map of faults and earthquakes recorded from the Monterey Peninsula to Pigeon Point, including the new offshore

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Shaded relief image of the Santa Rosa area showing active faults
April 14, 2016

Santa Rosa area showing active faults

Shaded relief image of the Santa Rosa area showing active faults (black lines) and the detailed rupture pattern of the Rodgers Creek Fault where it crosses central Santa Rosa (in red). The orange, bean-shaped area represents the dense, magnetic body of rock on the east side of the fault beneath Santa Rosa. This body of rock may be largely responsible for the pattern of

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Exposed faults
September 10, 2011

Exposed faults

Two faults (located on either side of project geologist Chris Fridrich) cutting Pleistocene fluvial gravels on the northern edge of the Poncha mountain block. These and other young faults exposed in area help reveal the latest kinematic (movement) and paleostress histories of the mountain block.

Image shows an aerial view of the San Andreas Fault
November 30, 2000

San-Andreas Fault

Aerial photo of the San Andreas Fault in the Carrizo Plain. By Ikluft - Own work, GFDL, https://commons.wikimedia.org/w/index.php?curid=3106006

Interactive Quarternary Fault Database

Interactive Quarternary Fault Database

This database contains information on faults and associated folds in the United States that demonstrate geological evidence of coseismic surface deformation in large earthquakes during the Quaternary (the past 1.6 million years).

 location of and evidence for recent movement on active fault traces within the Hayward Fault Zone, California

Traces of the Hayward Fault, California

The purpose of this map is to show the location of and evidence for recent movement on active fault traces within the Hayward Fault Zone, California.  The mapped traces represent the integration of the following three different types of data: (1) geomorphic expression, (2) creep (aseismic fault slip),and (3) trench exposures. 

Attribution: Natural Hazards
Map of known active geologic faults in the San Francisco Bay region

Map of known active geologic faults in the San Francisco Bay region

Map of known active geologic faults in the San Francisco Bay region, California, including the Hayward Fault.  The 72 percent probability of a magnitude (M) 6.7 or greater earthquake in the region includes well-known major plate-boundary faults, lesser-known faults, and unknown faults.  The percentage shown within each colored circle is the probability that a M 6.7 or

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