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San Bernardino County Earthquake Fault Map

View earthquakes for the last 30 days

San Bernardino, Fontana, Ontario, Rancho Cucamonga, and Victorville Faults

San Bernardino, located in Southern California, is situated near several significant earthquake faults. Here are some of the notable faults in the region:

1. San Andreas Fault: While not directly adjacent to San Bernardino, it's the most well-known fault in California and poses a seismic threat to the entire region, including San Bernardino.
2. San Jacinto Fault Zone: This fault system runs through the region near San Bernardino and is known for its activity. It's considered the most active fault zone in Southern California.
3. Cucamonga Fault: Located north of San Bernardino, it's part of the complex fault network in the region.
4. Elsinore Fault Zone: Situated southwest of San Bernardino, it's another significant fault capable of producing large earthquakes.

Earthquake Hazards:

In the event of a major earthquake near San Bernardino, several hazards could occur:

• Ground Shaking: This can cause structural damage to buildings and infrastructure, especially older structures that may not be retrofitted to current seismic standards.
• Liquefaction: Areas with loose, water-saturated soils (like near rivers or old lake beds) could experience liquefaction, where the ground temporarily behaves like a liquid during shaking, causing buildings to sink or tilt.
• Landslides: Steep slopes and hillsides could experience landslides or debris flows, particularly in areas with weakened soils due to saturation or shaking.
• Building and Freeway Collapse: Older buildings and bridges, particularly those not retrofitted for earthquakes, could collapse, posing risks to occupants and transportation routes.
• Fires: Earthquakes can rupture gas lines and cause electrical sparks, leading to fires that can spread rapidly, especially in urban areas.

Areas Facing Worst Shaking:

Areas near the active faults, particularly along the San Jacinto Fault Zone and other nearby faults, would likely experience the strongest shaking. Specific neighborhoods and communities close to these faults would be most vulnerable.

Major Earthquakes in the Last 100 Years:

Several significant earthquakes have impacted the San Bernardino area in the last century, including:

• Landers Earthquake (1992): Magnitude 7.3 earthquake that affected the Mojave Desert region, including San Bernardino County.
• San Jacinto Earthquake (1918): A major earthquake with an estimated magnitude between 6.7 to 7.2 that impacted the region, including San Bernardino.
• Hector Mine Earthquake (1999): Magnitude 7.1 earthquake located near Landers, affecting nearby regions including San Bernardino.

These earthquakes highlight the seismic activity and risks associated with living in San Bernardino and the surrounding areas. Preparedness and awareness of earthquake hazards are crucial for residents and authorities alike.

San Bernardino Fault Map

Fault Attributes Key

NAME is an 80-character field for the name of the fault (including section name,
i.e., Denali fault, Holitna section). Fault and section are lower case.

CODE is a three-integer field.that defines certainty or reliability of field mapping
(integer one), time of most recent movement (integer two), and amount or rate of slip (integer three).
CODE is composite of the single integer fields ACODE, SLIPCODE, and FCODE
and determines the line type (fault trace) to be plotted.

NUM is a six-character unique USGS identifier that defines a fault or section id. Simple fault
ids are only numeric; section ids are alpha numeric.

AGE is the upper bounding time of the most recent surface-deforming earthquake. The allowable
choices are provided in a pull-down menu.

ACODE is the second integer in CODE and defines the upper bounding time of the most recent
surface-deforming earthquake.
Permissible values are between 1 and 6: 1=historic «150 years; red =cmyk 1096680);
2= post glacial (15,000 years; orange = cmyk 1 38 1000);
3 = late Quaternary «130,000 years; green> cmyk 1002500);
4 =middle and late Quaternary «750,000 years: blue > cmyk 1004440);
5 =Quaternary «1,600,000 years; black 5);
6 = Class B (black halftone)
In the text documentation, Quaternary faults (integer two, 1-5) are Class A structures. Questionable or
suspected structures are Class B (integer two, 6).

SLIPRATE is the assigned slip rate category.

SLIPCODE is the third integer in CODE and defines the assigned slip rate category. Permissible
values are between 1 and 4 and determines line width:
1=>5 mm/year (extra wide; .048):
2 =1-5 mm/year (wide; .0325):
3 =0.2-1 mm/year (medium; .025);
4 =<.2 mm/year (thin; .015)

SLIPSENSE is normal, reverse, strike slip, thrust

DIPDIRECTION is one of the eight quadrant dip directions for the entire fault or section, not the
individual arc. C = center E =east N_ =north NE =northeast NW =northwest S =south SE =southeast SW =
southwest W_ =west
SLIPDIRECT (we are not using that field anymore and can be left empty) FCODE is the first integer
in CODE and defines how well the fault is located and expressed in the landscape. Permissible values are

between 1 and 3:
1 = fault landforms are more continuous than discontinuous and mapping is accurate at
given MAPPEDSCALE (solid);
2 = fault landforms are more discontinuous than continuous and mapping is accurate at
given MAPPEDSCALE (dashed);
3 = location of fault is inferred (dotted)
FTYPE is one of three allowable choices provided in a pull-down menu: Well constrained (FCODE 1),
Moderately constrained (FCODE 2), and Inferred (FCODE 3)

MAPPEDSCALE is one of four allowable choices provided in a pull-down menu.
Mapped scale will control visualization of the fault at various scales.
1:24,000, fault should be more continuous than discontinuous and mapping is accurate at <10,000 scale.
1:50,000, fault should be more continuous than discontinuous and mapping is accurate at <25,000 scale.
1:100,000, fault could be more discontinuous than continuous and mapping is accurate at <50,000 scale.
1:250,000, fault location may be inferred or is poorly constrained.



Data source: USGS
CCCarto is not responsible for data errors or omissions, use as reference only.
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