TIME: Almanac 1990/1990 Time Magazine Compact Almanac, The (1991)(Time).iso/time/103089/10308900.054

Text File | 1990-09-18 | 8KB | 147 lines

NATION, Page 42

The Benefits of Being Prepared

Emergency planning paid off but did not prevent two disastrous

collapses

By Janice Castro


    The enormous energy and resources that Californians have
invested in getting ready for the Big One were amply rewarded last
week. Since 1971, construction codes have been tightened, buildings
have been reinforced, emergency backup water supplies and
communications systems have been secured. In communities throughout
the state, fire and police departments regularly practice
earthquake evacuation and rescue responses, and neighborhood groups
have organized self-help efforts.

    Those precautions saved hundreds of lives. In San Francisco
modern office high-rises, many standing on huge steel-and-rubber
springs deep below their foundations, rode out the bucking
movement, bouncing and swaying as much as 30 ft. from side to side
without cracking open. Within minutes after the quaking subsided,
emergency response teams, honed by hundreds of hours of drills,
began rescuing victims, sealing off dangerously weakened structures
and coordinating relief efforts.

    Perhaps the most important planning efforts concerned ways of
coping in the immediate aftermath of a disaster. The Pacific Gas
& Electric Co. quickly shut off power in San Francisco to minimize
chances that a spark might ignite gas leaking from ruptured lines.
As a result, only seven buildings were lost to fire. Frightened
residents in dozens of towns could find detailed instructions on
household safety measures in their telephone books.

    But as state and local officials were collecting
congratulations on their efforts last week, troubling questions
were being raised about two catastrophes: the collapse of a stretch
of Interstate 880 in Oakland and the fall of a 50-ft. span on the
Bay Bridge, which connects Oakland and San Francisco. In
concentrating on the destructive potential of buildings, had
government disaster planners overlooked the fragile condition of
heavily traveled highways and bridges?

    I-880, also known as the Nimitz Freeway, collapsed when dozens
of its concrete vertical support columns shattered during the
violent shaking of the earthquake. Steel support rods inside the
columns snapped like raw spaghetti under the multimillion-pound
weight of the four-lane upper roadway. Some construction experts
last week expressed outrage that the steel rods inside the columns
had not been reinforced to help them withstand a powerful quake.
Said Peter Lehrer, co-chairman of the Lehrer McGovern Bovis
construction firm, which managed the restoration of the Statue of
Liberty and Ellis Island: "There is no excuse for what happened on
the Nimitz. We have had the technology to guard against this sort
of collapse for years."

    There were reports that state officials had long known the
freeway, completed in 1957, was dangerously weak but had moved
slowly to mount a major renovation of the structure. Calling for
a state investigation last week, Governor George Deukmejian said
he had just learned that a 1982 state study concluded that I-880
needed major reinforcement to prevent its collapse in a strong
quake. Engineering experts now say that simply wrapping the
concrete columns in steel sheathing -- a common method used to
shore up older bridges and highways -- might have substantially
reduced the damage. Even more disturbing are the suspicions of some
engineers that initial reinforcement work done on the freeway
during the 1970s may have contributed to its collapse. In an
attempt to strengthen the roadbed, steel cables were used to
connect the road's slabs. But as sections of the highway began to
collapse, these cables may have produced a domino effect, pulling
down one section after another.

    In addition to structural flaws in the highway, the condition
of the ground it stood on may have contributed to the collapse.
Like the buildings that toppled in San Francisco's Marina district,
parts of the freeway are built on landfill in an area that was once
under San Francisco Bay (30% of the land under the bay has been
reclaimed by landfill since the turn of the century).

    Under the enormous forces exerted by earthquakes, such landfill
typically liquefies below its surface, turning into slush as the
water is squeezed out. Because this quivering mixture amplifies the
shaking motion of an earthquake, structures built on landfill are
subjected to far more complex and powerful twisting and shaking
than those that stand on bedrock. Stark evidence of the difference
could be seen last week, as houses on bedrock stood intact across
the street from ruins.

    Design flaws also seem to have contributed to the fall of part
of the Bay Bridge, which consists of two differently engineered
sections. Between San Francisco and Yerba Buena Island, the Bay
Bridge is, like the Golden Gate, a suspension span built to
withstand winds of 100 m.p.h. by swinging from side to side.
Between the island and Oakland is the section that failed. It is
of a far less flexible, cantilevered design in which the roadway
rests on vertical steel support towers. During the tremor, one such
tower swayed, snapping off the 2-in. bolts that attached it to the
upper roadway and allowing a 50-ft. section to crash down on the
lower level.

    Several other double-deck highways in San Francisco also
sustained heavy damage in last week's quake. On Thursday, after
large fissures were spotted in half a dozen support structures,
officials closed the Embarcadero Freeway, which swoops high above
the city's financial district. Cracks were also found in the
Southern and Central freeways, which bisect other downtown
districts. Although some experts insist that safe double-deck roads
can be built, angry demands that all such highways in California's
quake zone be dismantled are already being heard. In Los Angeles
last week, County Supervisor Kenneth Hahn called for a halt in
construction of a second deck over 2.6 miles of the Harbor Freeway.

    Even thousands of miles away from the epicenter, Americans were
warily eyeing their highways and buildings and calling for better
planning. Along the New Madrid fault, which runs 150 miles
southeast of St. Louis, seismic experts say that within the next
ten years there is a 33% chance of a quake as powerful as the one
that hit San Francisco. Many East Coast residents who think of
earthquakes as a California problem were reminded last week that
New York City, which in 1985 sustained a 4.0-point quake with no
significant damage, may be struck by a quake even more powerful
than the San Francisco temblor within the next 20 years. Such a
quake would wreak havoc on New York City, with its shockingly
decrepit bridges and highways, some of which are only now getting
the attention they urgently need.

    Final explanations of why some California structures collapsed
and others did not cannot be arrived at overnight. Just as
researchers must analyze air disasters for as long as a year to
determine the precise cause, scientists at earthquake research
centers from Berkeley to Buffalo will use data from the wreckage
to simulate last week's quake. By using sophisticated computers to
study the wrenching forces, they hope to learn how to limit the
damage.

    Ultimately, these studies will yield valuable lessons in how
to save lives and protect property. For example, one new technology
based on studies of earlier quakes protects high-rise towers and
bridges with shock absorbers made of rubber and lead. As small as
toaster ovens, these seismic shock absorbers can reduce the force
of a mighty 8.0 quake to a mere 5.0, hardly powerful enough to
crack a sidewalk. As Californians marveled about how much more
horrific last week's quake might have been without their
preparations, they were also looking at a laboratory for
prevention. Excruciating as the lessons are, tough-minded planning
can reduce the tragic price the next time the earth heaves and
buckles underfoot.


-- Robert W. Hollis/Oakland, Jeanne McDowell/Los Angeles and
   Sophfronia Scott/New York