significant if the facility is located outside of areas that
been engineered, well compacted, and placed with
could be subject to inundation. City, county, state, and
engineering inspection and testing.
federal agencies (e.g., U.S. Army Corps of Engineers,
U.S. Bureau of Reclamation) should be contacted as
(e) The building is located below a slope, is a
needed to ascertain the location of such water retention
horizontal distance of at least twice the slope height
structures and inundation areas.
from the toe of the slope, and the slope is underlain by
geologic materials as stated in (d) above.
F-4. Evaluation Procedures
(2) Example. An example of screening for the
hazard of landsliding is given in Appendix G.
The following sections describe evaluation procedures
for hazards that are not screened out using the
e. Flooding. The hazard of flooding due to many
procedures in paragraph F-3. An important element in
causes, including tsunami, seiche, tectonic movements,
the evaluations is to assess the consequences of the
and failure of water retention structures can be assumed
hazard in terms of the significance of the hazard to the
to be not significant if the facility is not located near a
structure. Thus, for example, the occurrence of
body of water nor in an area that could be inundated by
liquefaction may or may not pose a significant risk to a
the hazard.
structure depending on whether or not significant
ground and structural deformations could occur as a
(1) Tsunami and seiche. For facilities located near
result of liquefaction. The possible conclusions from
coastal waters, the hazard of tsunami due to
these evaluations are: (1) a hazard posing a significant
earthquake-induced seafloor displacements can be
risk to structures does not exist; (2) the hazard exists,
assumed to be not significant if the ground surface
but further structural evaluation is required to ascertain
elevation of the facility above sea level is greater than
whether the risk to structures is significant; or (3) the
the estimated potential maximum tsunami wave height
hazard exists, poses a significant risk of damage to a
as given in Figure F-9. Although records of seiche
structure and mitigation measures should be
occurrence are relatively incomplete, it would appear to
considered.
be rare for a seiche wave to exceed about 2 m (7 feet)
in height. Therefore, the seiche hazard can be screened
a. Estimated ground motion. When estimates of
out for sites located more than 2 m (7 feet) above the
earthquake ground shaking parameters are required for
adjacent water body.
these evaluations, they should be consistent with MCE
ground motions as defined in Chapter 3. The
(2) Landsliding-induced tsunami. The potential for
corresponding performance objectives should be
rapid hillside landsliding into bodies of water can be
collapse prevention for Seismic Use Groups I and II;
assumed to be not significant if slopes in similar
for Seismic Use Groups IIIH and IIIE, performance
geologic materials in the vicinity have performed well
objectives should be 2B and 3B, respectively, as
historically and the slopes are not oversteepened. If
defined in Chapter 4. Estimates of the duration of
similar slopes and geologic formations extend
strong shaking should be based on the assumption of
underwater, they are also unlikely to be susceptible to
the occurrence of maximum earthquakes in the site
significant submarine landsliding. Loose or soft
region.
submarine deposits such as deltaic deposits could be
susceptible to rapid landsliding.
b. Surface fault rupture. After a site has been
(3) Flooding due to tectonic movements. The
evaluated by the screening criteria developed above
potential for flooding due to tectonic movements can be
and (1) either there is insufficient information to rule
assumed to be not significant if the regional faults
out a surface fault rupture hazard, or (2) there is
would not be expected to produce tectonic movements
seismic, geomorphic, and/or geologic data that suggests
to a degree that could interact with water bodies and
active fault(s) might be present at or near
cause flooding. Such judgements should be made by
experienced geologists or seismologists who are
knowledgeable of the regional tectonic setting.
(4) Flooding due to failure of water retention
structures. The potential for flooding due to the failure
of water retention structures can be assumed to be not
F-16
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