Few of those living around major faults really believe an earthquake is likely to strike until it actually does - and then, of course, it is too late.
It is unlikely that most Americans will experience a large,
damaging earthquake in their lifetime. Earthquakes occur in only a
few places in the U.S., primarily California and Alaska.
While earthquakes occur in "geologic time" which is far
slower than that which we usually use to judge whether something is
of immediate concern to us, records show that some seismic zones in
the U.S. experience moderate to major earthquakes about every 50 to
70 years while other areas have "repeat" or
"recurrence" intervals of about 200 to 400 years. However,
these probabilities or "odds" are simply best estimates,
and one or several earthquakes could occur in a much shorter than
average period. The rule of thumb cited by some seismic experts is:
"The further you are from the last one, the closer you are to
the next one."
More than 40 of the 50 states as well as many U.S. territories
are at risk from earthquakes. In fact, the three greatest
earthquakes occurred not on the West Coast, but in the East and
Midwest.
Buildings built in accordance with seismic provisions or "to
code" will not suffer any damage in an earthquake
Local building codes and regulations in areas of seismic risk
generally include seismic safety provisions.
Most residences in Idaho are low-rise wood-framed buildings that generally survive quite well in larger earthquakes as long as they are securely bolted to their foundations.
In older homes most mudsills were nailed to the foundation using 40d nails, approximately 4-41/2 inches in length. In homes built after 1950, the Uniform Building Code (UBC) requires the use of anchor bolts to secure the mudsills to the foundation. This type of structural work is beyond the ability of most homeowners and should be done by a licensed contractor.
Much of the property damage and a small number of injuries from earthquakes result not from cracking buildings but from non-structural objects flying around and slamming into human flesh. Homeowners can be far more earthquake savvy by securing furniture, TV sets, bookcases and especially water heaters to the walls. Fires in the wake of an earthquake often do more damage than the quake itself, and many a fire has been caused by a top-heavy water heater keeling over, ripping a gas line out of a cellar wall and breaking it in the process.
See:
Non-Structural Safety
Plan and Prepare