TM 5-852-1/AFR 88-19, Volume 1
in interpretation of subsurface conditions. Because
signed for seismic forces where required by the
relationships between vegetation and subsurface
probability, in severity, frequency and potential damage,
conditions determined in one geographical area do not
of seismic ground shaking or tsunamis (seismic sea
necessarily apply in an environmentally different area, a
waves). This is in addition to design for dead, live, snow
specific correlation should be established, verified, or
and wind structural loads. Though risk from earthquake-
known in any substantially different geographical area in
generated forces is not very high over much of the Arctic
which such information may be used.
and Subarctic, risk of major or great damage exists in
certain areas, such as in Alaska, south of about
Fairbanks. TM 5-809-10/NAV FAC P-355/AFM 88-3,
2-8.
Special surficial features and markings
Chap. 13 provides criteria and guidance for seismic
design.
Characteristic features and markings are produced on
the ground in northern regions by permafrost
2-10.
Graphic summaries
degradation, frost action, mass wasting (i.e. creep, frost
a. To aid in understanding the environmental
creep and frost sloughing) and other natural phenomena.
These features include solifluction markings, pingos,
conditions at specific locations and their variations
thermokarst depressions and patterned ground. They
through the seasons, graphic summaries such as the
can serve as important indicators of ground conditions,
one for Barrow, Alaska, shown in figure 2-14 (fold-out
including the likelihood of the presence of permafrost
located in back of manual), are useful.
b. Seismic probability, snow load and other
and ground ice.
design data may also be summarized on a regional basis
to provide engineers with values to be adopted in design
2-9.
Seismic activity
work.
Construction in the Arctic and Subarctic should be de-
2-19
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