Page 624 - 2018 National Home Improvement

2018 National Home Improvement Estimator, All Rights Reserved Page 497

Chapter 18, Earthquake Damage

Most homes built more than 100 years ago were constructed with little or no regard for seismic safety.
Earthquakes were considered random acts of nature that couldn't be forecast or prevented. Damage was
inevitable - but only for the unfortunate few in the area affected. And there was no way to anticipate who
would be affected. So there was little reason, and no practical way, to build for earthquake safety.

Since the 1930s, our perspective has changed, largely due to analysis of damage and loss of life from
earthquakes in California and elsewhere. Earthquakes remain unpredictable and inevitable. But damage
and loss of life is not. Materials have improved, codes have improved, our understanding of how
earthquakes affect structures has improved. Homes and commercial buildings constructed under
modern codes, such as the International Residential Code (IRC) and the International Building Code
(IBC), have to meet the seismic safety standards appropriate for the community where built.

But for many years to come, older buildings along the Pacific rim will be susceptible to damage or
destruction from earthquake. Buildings along the central Mississippi valley, the eastern seaboard and in
other areas may also be damaged by seismic activity. In the 20 years between 1975 and 1995, there
were only four states that did not have at least one earthquake: Florida, Iowa, North Dakota, and
Wisconsin.

Types of Damage
Damage from earthquakes can be either structural or cosmetic. Any compromise in the ability of a
building to resist expected loads is considered structural damage. Some structural damage can be
repaired. For example, it's common for wood-frame walls, window openings and doorways to be twisted
out of alignment by an earthquake. If the framing is otherwise sound, the wall can be braced back into
alignment and secured in place and may last for many years.

Other structural damage is more difficult to repair. For example, the massive structural failure in Figure
18-1 makes this home a candidate for demolition rather than improvement. Expect local authorities to
prohibit entry into this home, at least until a licensed structural engineer makes an evaluation of whether
it's safe to re-enter the building. The International Property Maintenance Code (IPMC), where adopted,
gives the building department authority to deal with public hazards like this. A building official will
usually notify the property owner of the action required. If the owner doesn't comply, the building official
can expel the occupants, secure the building or even demolish the structure.