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Earthquake
Hazards
Pictured above: A map showing zones
of seismic hazards in the conterminous United States. Warm colors
indicate areas in which hazards are greater. As the map indicates,
destructive earthquakes may occur across the nation.
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Earthquakes represent potential hazards to the visitors, staff, and infrastructure
of many of the nation's parks. The tectonic forces that created
so many of the parks' spectacular mountain ranges and volcanoes
possess the capacity for tremendous destruction. Many National Park
Service units are located in the seismically active areas studied
by the USGS.
The mission of the USGS Earthquake Hazards Program is to provide
and apply relevant earthquake science information and knowledge
for reducing deaths, injuries, and property damage from earthquakes
through understanding of their characteristics and effects and by
providing the information and knowledge needed to mitigate these
losses. USGS science products for planning and emergency management
agencies include information on earthquake probabilities, shaking
hazard maps, and liquefaction hazards.
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| Pictured above: Map
showing the location of the Nov. 3, 2002 earthquake near Denali
National Park. The M7.9 mainshock is shown as a filled white
circle and the October 23, 2002, M6.7 foreshock as an open white
circle. Other circles represent associated earthquakes that
occurred between October 22 and November 20, 2002, with a depth
of 35km or less. |
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Many National Park Service units are located in the seismically
active areas studied by the USGS Earthquake Hazards Program. For
instance, several park service units lie along the San Andreas fault
system. USGS science products for planning and emergency management
agencies include information on earthquake probabilities, shaking
hazard maps, and liquefaction hazards.
A magnitude 7.1 earthquake rocked the Joshua Tree National Park
region at 2:46 a.m. local time October 16, 1999. This aerial photograph,
shown at right, shows the rupture in the earth's surface
about 32 miles north of Joshua Tree. Arrows show the direction
the ground moved. Photo courtesy of Paul "Kip" Otis- Diehl,
U.S. Marine Corps, Twenty-Nine Palms.
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The image at left shows active fault strands of the San Francisco Bay region
in red. The San Andreas fault, which
runs from the upper left corner to the lower right corner of
the image, cuts through the Golden Gate National Recreation
Area and Point Reyes National Seashore. In 1906, the rupture
that caused the Great San Francisco Earthquake also wrenched
Point Reyes several meters northward relative to San Francisco.
The USGS has monitoring instruments located in these National
Park Service units.
Pictured above: The 1906 rupture
of the San Andreas fault at the old Skinner Ranch near the visitor
center and headquarters of Point Reyes National Seashore. Photo
by USGS geologist G.K. Gilbert, 1906: Steinbrugge Collection
of the UC Berkeley Earthquake Engineering Research Center. |
Pictured above: A USGS drill rig
in Golden Gate National Recreation Area, preparing for the
installation of a buried ground-deformation station. |
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