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Structures generally considered at-risk for damage or failure in a major earthquake include:

Soft-story: Wood-framed buildings with an open ground level typically used for tuck-under parking, with
one or more stories of dwelling units above. Extremely popular as a means of conserving lot space,
buildings of this type constructed prior to 1978 have been proven vulnerable to collapse from seismic
activity.
Unreinforced Masonry: These structures are characterized by walls and other building components
made of brick or other masonry materials not braced with rebar or another reinforcing material. These
facades can collapse during an earthquake. Most of these buildings were identified as part of an earlier
state mandate, but there are still thousands that have yet to be retrofitted.

Tilt-up: Tilt-up construction is a cost-effective technique of pouring a building’s walls directly at the
jobsite and then raising or “tilting” the panels into position. Many of these structures built prior to the
1970s were constructed with limited or weak roof connections and diaphragms that can fail during an
earthquake.

Non-ductile Concrete: These buildings are characterized as having concrete floors and/or roofs
supported by concrete walls and/or frames. Their rigid construction and limited capacity of structures
built prior to 1978 to absorb the energy of ground shaking makes them at risk for collapse.

Steel Moment Frame: This building technique, used in the first skyscraper, was most commonly used in
the 1960s to 1990s. Those constructed prior to 1994 can sustain brittle fracturing of the steel frames at
welded points between the beams and columns.

When Mayor Garcetti signed L.A.’s ordinance into law, he said he did it not only for life and safety
issues, but to protect the city’s ability to function after that long-anticipated monster of an earthquake
strikes. Public response to the new law has been much better than expected, particularly among
building owners, who have recognized that it makes good business sense to retrofit their properties.

To date, more than 15 percent of the city’s
13,500 structures tagged for retrofits have
begun the process with engineering studies
and/or construction.

“That means property saved, and more
importantly, people saved,” Garcetti told
the Los Angeles Times in 2017. “We just
pray the earthquake doesn’t come before
we finish this work. And when it does
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come, we’re all going to be better off.”
A Matter of National Concern

The White House, in its National Security
Strategy dated December 2017, listed the
promotion of American resilience against
natural disaster as one of the country’s
primary security issues for the coming year.

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Yucaipa Valley Water District - March 8, 2018 - Page 20 of 40