Environmental Engineering Reference
In-Depth Information
TABLE 11.9
System for Classification of Fault Activity Based on Available Data
a
Criteria
Activity Classification and Definition
Historical
Geological
Seismological
Studies to Define Further Activity
Active — a tectonic fault which has a history
1. Surface faulting
1. Geologically young
b
Earthquake
Additional investigations and
of strong earthquakes and surface rupture,
and associated
deposits have been dis-
epicenters are
explorations are needed to define:
or a fault which can be demonstrated to
strong earthquakes
placed or cut by faulting
assigned to
1. The exact location of individual
have an interval of recurrence short enough
2. Tectonic fault creep,
2. Fresh geomorphic
individual faults
fault traces
to be significant during the life of the
or geodetic
features characteristic of
with a high
2. The recurrence interval
particular project. The recurrence time
indications
active fault zones
degree of
3. The projected magnitude of
period considered significant for
of movement
present along fault trace
confidence
future events
individual projects will vary
3. Physical groundwater
4. The type of surface deformation
with the consequence of activity
barriers produced in
associated with the surface faulting
geologically young
b
5. The probable source of energy
deposits
release with respect to the site
Potentially active — a tectonic fault which
No reliable report
1. Geomorphic features
Alignment of
Additional investigations are
has not ruptured in historic time, but
of historic
characteristic of active
some earthquake
needed to resolve:
available evidence indicates that rupture
surface faulting
fault zones subdued, eroded
epicenters along
1. The time interval of past activity
has occurred in the past and the recurrence
and discontinuous
fault tract, but
2. The recurrence of activity
period could be short enough to be of
2. Faults are not known to cut
locations are
3. The possible locations of the
significance to particular projects
or displace the most recent
assigned with a
individual fault traces
alluvial deposits, but may be
low degree
The classification becomes less
found in older alluvial deposits
of confidence
important if the fault does not cross
3. Water barrier may be
the project site and a known active
found in older materials
fault which is capable of producing
