Environmental Engineering Reference
In-Depth Information
Activity uncertain — a reported fault for
Available information is insufficient to provide criteria that are definitive
This classification indicates that
which insufficient evidence is available
enough to establish fault activity. This lack of information may be due to the
additional studies are necessary if
to define its past activity or its recurrent
inactivity of the fault or due to a lack of investigations needed to provide
the fault is found to be critical to
interval. The following classifications can be
definitive criteria
the project. The importance of a
used until the results of additional studies
fault with this classification
provide definitive evidence
depends upon the type of structure
involved, the location of the fault
Tentatively active — predominant evidence
Available information suggests evidence of fault activity, but evidence is
with respect to the structure, and
suggests that the fault may be active even
insufficient to be definitive
the consequences of movement
though its recurrence interval is very long
or poorly defined
Tentatively inactive — predominant
Available information suggests evidence of fault inactivity, but evidence is
evidence suggests that fault is not active
insufficient to be definitive
Inactive — a fault along which it can be
No historic activity
Geomorphic features characteristic
Not recognized
No additional investigations are
demonstrated that surface faulting has not
of active fault zones are not
as a source of
necessary to define activity
occurred in the recent past, and that the
present and geological evidence
earthquakes
recurrence interval is long enough not to
is available to indicate that the
be of significance to the particular project
fault has not moved in the recent
past and recurrence is not likely
during a time period considered
significant to the site. Should
indicate age of last movement:
Holocene, Pleistocene,
Quaternary, Tertiary, etc.
a
From Cluff et al. (1972).
b
The exact age of the deposits will vary with each project and depends upon the acceptable level of risk and the time interval which is considered significant for that project.