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Quaternary Fault and Fold Database of the United States
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Frequently-anticipated questions:
- Title: Quaternary Fault and Fold Database of the United States
- Abstract:
-
This map layer contains locations and information on faults and associated
folds, in the United States, that are believed to be sources of
significant earthquakes (those of magnitude 6 or greater) during the past
1,600,000 years.
- Supplemental_Information:
-
The most up-to-date version of this data set as well as detailed
descriptions and references for each fault are available through the
online Quaternary Fault and Fold Database of the United States, at
<http://earthquake.usgs.gov/regional/qfaults/>. In addition, in the
Earthquake Hazards Program Quaternary Faults and Fold Database viewer
<http://gldims.cr.usgs.gov/qfault/viewer.htm>, and in the National Atlas
Map Maker <http://nationalatlas.gov/natlas/Natlasstart.asp>, the geologic
structures are linked to the database. The Quaternary Fault and Fold
Database of the United States is intended to be the USGS archive for
historic and ancient earthquake sources used in current and future
probabilistic seismic-hazard analyses. The database summarizes important
information on paleoseismic (ancient earthquake) parameters, compiled from
thousands of journal articles, maps, theses, and other documents. It
includes information on geographic, geologic, and paleoseismic parameters
that are deemed critical to making geologic-based assessments of seismic
hazards. In addition, it provides narrative comments that clarify,
justify, or expound upon these parameters.
- How should this data set be cited?
Kathy Haller, U.S. Geological Survey, Richard Dart, U.S. Geological Survey, and Susan Rhea, U.S. Geological Survey, 200501, Quaternary Fault and Fold Database of the United States: National Atlas of the United States, Reston, VA.
Online Links:
- What geographic area does the data set cover?
- West_Bounding_Coordinate: -126.39
- East_Bounding_Coordinate: -70.81
- North_Bounding_Coordinate: 48.89
- South_Bounding_Coordinate: 23.19
- What does it look like?
- <http://gldims.cr.usgs.gov/qfault/viewer.htm> (Online viewer)
-
Viewer for the Quaternary Fault and Fold Database.
- Does the data set describe conditions during a particular time period?
- Calendar_Date: 2005
- Currentness_Reference: Publication date
- What is the general form of this data set?
- Geospatial_Data_Presentation_Form: Vector digital data
- How does the data set represent geographic features?
- How are geographic features stored in the data set?
This is a Vector data set.
It contains the following vector data types (SDTS terminology):
- GT-polygon composed of chains (24)
- Complete chain (45814)
- What coordinate system is used to represent geographic features?
Horizontal positions are specified in geographic coordinates, that is, latitude and longitude.
Latitudes are given to the nearest 0.000278.
Longitudes are given to the nearest 0.000278.
Latitude and longitude values are specified in Decimal degrees.
The horizontal datum used is North American Datum of 1983.
The ellipsoid used is GRS1980.
The semi-major axis of the ellipsoid used is 6378137.
The flattening of the ellipsoid used is 1/298.257222.
- How does the data set describe geographic features?
- Quaternary faults (described by qfaultl_25.dbf)
- Linear fault features in the conterminous United States.
(Source: U.S. Geological Survey)
- Shape
- The representation of the entity in the data.
(Source: National Atlas of the United States)
Value | Definition |
Polyline | 1-dimensional element that may or may not surround a 2-dimensional
element.
|
- Qfaultl_25
- Internal feature number.
(Source: National Atlas of the United States)
Range of values |
Minimum: | 1 |
Maximum: | 45814 |
- Name
- The fault name.
(Source: U.S. Geological Survey)
Value | Definition |
<Blank> | The fault name is unknown.
|
There is no predefined set of valid fault names.
- Code
- A 3-digit code used for symbolizing faults. Each digit has a particular
meaning:
First digit: fault visibility code
1 = Exposed
2 = Concealed
3 = Inferred
Second digit: fault age code
1 = Historic; referenced in dated recorded history, generally < 150
years
2 = Holocene < 15,000 years
3 = Late Quaternary < 130,000 years
4 = Mid to late Quaternary < 750,000 years
5 = Quaternary < 1,600,000 years
6 = Class B; fault structures of questionable seismogenic origin that
may be older than the Quaternary
Third digit: fault slip rate code
1 = > 5 mm/year
2 = 1 - 5 mm/year
3 = 0.2 – 1 mm/year
4 = < 0.2 mm/year
(Source: National Atlas of the United States)
There is no predefined set of valid fault codes.
- Num
- The fault index number, which is linked to the online fault database.
(Source: U.S. Geological Survey)
Value | Definition |
<Blank> | There is no information about the fault available in the online
fault database.
|
There is no predefined set of valid fault index numbers.
- Slip
- A four-character code defining the fault type and slip direction. The
first two characters describe the fault type:
N_ = normal
R_ = reverse
SS = strike-slip
T_ = thrust
The second two characters describe the slip direction:
__ = no data
C_ = center
E_ = east
LL = left lateral
N_ = north
NE = northeast
NW = northwest
RL = right lateral
S_ = south
SE = southeast
SW = southwest
W_ = west
(Source: U.S. Geological Survey)
Value | Definition |
<Blank> | The fault type and slip direction are not known.
|
There is no predefined set of valid slip codes.
- Age
- The age of the fault in years.
(Source: U.S. Geological Survey)
Value | Definition |
<1,600,000 | The fault is less than 1,600,000 years old.
|
<750,000 | The fault is less than 750,000 years old.
|
<130,000 | The fault is less than 130,000 years old.
|
<15,000 | The fault is less than 15,000 years old.
|
<150 | The fault is historic (less than 150 years old.)
|
Class B | Class B faults may or may not be seismogenic (capable of generating
earthquakes) and may be older than the Quaternary.
|
Unknown | The age is undetermined, but researchers believe that fault motion
occurred in the Quaternary.
|
- Rate
- The rate of motion obtained when the amount of offset is divided by the
time interval. It is normalized to millimeters per year.
(Source: U.S. Geological Survey)
Value | Definition |
<0.2 | The rate of motion is less than 0.2 millimeters per year.
|
0.2-1 | The rate of motion is 0.2 to 1 millimeters per year.
|
1-5 | The rate of motion is 1 to 5 millimeters per year.
|
>5 | The rate of motion is greater than 5 millimeters per year.
|
- Slipsense
- The angle of dip of the fault and the relative direction of movement
across the fault.
(Source: U.S. Geological Survey)
Value | Definition |
Incomplete | The angle of dip and the relative direction of movement were not
reported in the referenced material for the fault.
|
LeftLateral | Horizontal displacement along a fault such that, in plan view, the
side opposite the viewer appears to have moved to the left. This
term is also known as sinistral.
|
Normal | A fault characterized by predominantly vertical displacement in
which the hanging wall moves downward with respect to the footwall
of the fault. If the fault surface is exposed, the footwall is the
side onto which water would drip. Generally, this type of fault is
a sign of tectonic extension.
|
Reverse | A fault in which the displacement is predominantly vertical, and
the hanging wall moves up with respect to the footwall. The
footwall is the side of the fault onto which water would drip if the
fault is exposed.
|
RightLateral | Horizontal displacement along a fault such that, in plan view, the
side opposite the viewer appears to have moved to the right. This
term is also known as dextral.
|
Thrust | A fault of less than 45° dip in which the displacement is
predominantly vertical, and the hanging wall moves up with respect
to the footwall. The footwall is the side of the fault onto which
water would drip if the fault is exposed.
|
- Dipdirecti
- The general direction of the fault dip which is the angle that the fault
is inclined from the horizontal plane.
(Source: U.S. Geological Survey)
Value | Definition |
Center | The direction of the dip is towards the center of a hole or
depression, as in a caldera or bowl.
|
East | The direction of the dip is toward the east.
|
North | The direction of the dip is toward the north.
|
Northeast | The direction of the dip is toward the northeast.
|
Northwest | The direction of the dip is toward the northwest.
|
South | The direction of the dip is toward the south.
|
Southeast | The direction of the dip is toward the southeast.
|
Southwest | The direction of the dip is toward the southwest.
|
Unspecified | The direction of the dip is unknown.
|
Vertical | The fault face is near vertical.
|
West | The direction of the dip is toward the west.
|
- Acode
- A code indicating the age of the fault in years before the present. The
code is used for symbolizing the lines in the map service and the
National Atlas.
(Source: U.S. Geological Survey)
Value | Definition |
1 | The fault age is historic.
|
2 | The fault age is Holocene, <15,000 years.
|
3 | The fault age is late Quaternary, <130,000 years.
|
4 | The fault age is mid-late Quaternary, <750,000 years.
|
5 | The fault age is Quaternary, <1,600,000 years.
|
6 | The fault age is class B. It is not thought to be seismogenic
(capable of producing earthquakes) and may be older than the
Quaternary.
|
- Wwwurl
- An identification code used to locate data in the online database.
This is used by the interactive map service at
<http://gldims.cr.usgs.gov/qfault/viewer.htm> and by
<http://nationalatlas.gov/natlas/Natlasstart.asp>
(Source: U.S. Geological Survey)
Value | Definition |
0 | No information about the fault is available in the online database.
|
Range of values |
Minimum: | 84 |
Maximum: | 35110 |
- Quaternary fault areas (described by qfaultp_25.dbf)
- Fault feature regions in the conterminous United States.
(Source: U.S. Geological Survey)
- Shape
- The representation of the entity in the data.
(Source: National Atlas of the United States)
Value | Definition |
Polygon | 2-dimensional element
|
- Area
- The size of the shape in square coverage units. In the distributed
file, coverage units represent square decimal degrees.
(Source: National Atlas of the United States)
Range of values |
Minimum: | 0.002 |
Maximum: | 28.349 |
- Perimeter
- The perimeter of shape in coverage units. In the distributed file,
coverage units represent decimal degrees.
(Source: National Atlas of the United States)
Range of values |
Minimum: | 0.191 |
Maximum: | 28.754 |
- Qfaultp_25
- Internal feature number.
(Source: National Atlas of the United States)
Range of values |
Minimum: | 2 |
Maximum: | 25 |
- Name
- The name of the fault region.
(Source: U.S. Geological Survey)
There is no predefined set of valid fault region names.
- Age_class
- A code indicating the age of the faults in years before the present.
The code is used for symbolizing the area in the map service and the
National Atlas.
(Source: U.S. Geological Survey)
Value | Definition |
1 | The fault age is historic, <150 years - 400 years.
|
2 | The fault age is Holocene < 15,000 years.
|
3 | The fault age is late Quaternary < 130,000 years.
|
6 | The fault age is class B. It is not thought to be seismogenic, and
may be older than the Quaternary.
|
- Num
- The fault index number(s), which is linked to the online database.
(Source: U.S. Geological Survey)
There is no predefined set of valid fault index numbers.
- Age
- The age of the faults in years before the present.
(Source: U.S. Geological Survey)
Value | Definition |
<1,600,000 | The faults are less than 1,600,000 years old.
|
<15,000 | The faults are less than 15,000 years old.
|
nodata | No data are available to determine the fault ages.
|
various | Multiple ages were reported.
|
- Rate
- The rate of motion obtained when the amount of offset is divided by the
time interval. It is normalized to millimeters per year.
(Source: U.S. Geological Survey)
Value | Definition |
<0.2 | The rate of motion is less than 0.2 millimeters per year.
|
nodata | The rate of motion is unknown; no data is available.
|
too few data | Not enough data are available to determine the rate of motion.
|
- Slipsense
- The angle of dip of the faults and the relative direction of movement
across the faults.
(Source: U.S. Geological Survey)
Value | Definition |
nodata | No data is available to determine the angle of dip.
|
normal | A fault characterized by predominantly vertical displacement in
which the hanging wall moves downward with respect to the footwall
of the fault. If the fault surface is exposed, the footwall is the
side onto which water would drip. Generally, this type of fault is
a sign of tectonic extension.
|
sinistral | Horizontal displacement along a fault such that, in plan view, the
side opposite the viewer appears to have moved to the left. This
term is also known as left lateral.
|
various | Faults are in a combination of dip directions.
|
- Dipdirection
- The general direction of the fault dip, which is the angle that a
fault is inclined from the horizontal plane.
(Source: U.S. Geological Survey)
Value | Definition |
S, N | The dips are toward the south and the north.
|
SE, NW | The dips are toward the southeast and the northwest.
|
SW | The dips are toward the southwest.
|
SW, NE | The dips are toward the southwest and the northeast.
|
V, SW | The dips are toward the southwest and the vertical.
|
nodata | The direction of the dips is unknown.
|
various | The direction of the dips varies.
|
- Wwwurl
- An identification code used to locate data in the online database.
This is used by the interactive map service at
<http://gldims.cr.usgs.gov/qfault/viewer.htm> and by
<http://nationalatlas.gov/natlas/Natlasstart.asp>
(Source: U.S. Geological Survey)
Value | Definition |
0 | No information about the fault is available in the online database.
|
Range of values |
Minimum: | 33814 |
Maximum: | 34137 |
- Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
- Kathy Haller, U.S. Geological Survey
- Richard Dart, U.S. Geological Survey
- Susan Rhea, U.S. Geological Survey
- Who also contributed to the data set?
- To whom should users address questions about the data?
These data are intended for geographic display and analysis at the
national level, and for large regional areas. The data should be
displayed and analyzed at scales appropriate for 1:250,000-scale data.
No responsibility is assumed by the National Atlas of the United States
in the use of these data.
- From what previous works were the data drawn?
- QFAULT (source 1 of 1)
-
U.S. Geological Survey, 2004, Quaternary Fault and Fold Database of the United States: U.S. Geological Survey, Denver, CO.
Online Links:
- Type_of_Source_Media: Electronic mail system
- Source_Contribution: Spatial and attribute information
- How were the data generated, processed, and modified?
- Date: Dec-2004 (process 1 of 1)
-
The U.S. Geological Survey Earthquake Hazards Program provided a
shapefile that was modified for use in the National Atlas Map Maker.
The file was reprojected and the datum was converted from the North
American Datum of 1927 to the North American Datum of 1983.
In addition, in the area of overlapping polygons, two polygons were
created, one for "St Louis-Cape Giradeau liquefaction" and one for
"Wabash Valley liquefaction features".
Data sources used in this process:
- What similar or related data should the user be aware of?
- How well have the observations been checked?
Fault characteristics, even where known in detail, are reported
in broad categories (for example "age less than 1,600,000 years").
The textual database contains more specific information about
each fault where details were available in published literature.
- How accurate are the geographic locations?
Locations of faults were taken from published literature; these
investigations were carried out at a variety of scales of observation,
hence some faults will be located more precisely and accurately than
others. In general the locations are accurate as observed on a
1:250,000 scale map, or within approximately 450 feet.
- How accurate are the heights or depths?
- Where are the gaps in the data? What is missing?
Faults in Alaska and Hawaii are not included. Data for California are
incomplete; not all faults are included.
- How consistent are the relationships among the observations, including topology?
Due to substantial differences in the geological setting and tectonic
activity, the central and eastern United States appear to have fewer faults
active in the Quaternary. This is partly a real phenomenon (the western US
has more tectonic activity) and partly a detection problem. For example,
the glacial sediments that cover much of the eastern Midwest conceal the
evidence that would be used to infer movement along underlying faults in the
Quaternary.
Are there legal restrictions on access or use of the data?
- Access_Constraints: None
- Use_Constraints:
-
None. Acknowledgment of the Quaternary Faults and Fold Database, the
U.S. Geological Survey, and (or) the National Atlas of the United
States of America would be appreciated in products derived from
these data.
- Who distributes the data set? (Distributor 1 of 1)
Earth Science Information Center, U.S. Geological Survey
507 National Center
Reston, VA 20192
1-888-ASK-USGS (1-888-275-8747) (voice)
- Contact_Instructions:
-
In addition to the address above there are other ESIC offices throughout
the country. A full list of these offices is at
<http://ask.usgs.gov/esic_index.html>.
- What's the catalog number I need to order this data set?
- What legal disclaimers am I supposed to read?
Although these data have been processed successfully on a computer system at
the U.S. Geological Survey, no warranty expressed or implied is made by the
U.S. Geological Survey regarding the utility of the data on any other
system, nor shall the act of distribution constitute any such warranty. No
responsibility is assumed by the U.S. Geological Survey in the use of these
data.
- How can I download or order the data?
- Availability in digital form:
- Cost to order the data: There is no charge for the map layer.
- Dates:
- Last modified: 08-Aug-2006
- Metadata author:
-
Peg Rawson
National Atlas of the United States
12201 Sunrise Valley Dr
Reston, VA 20192
703-648-4183 (voice)
[email protected]
- Metadata standard:
- FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
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