KCGarrigan.eq.fire

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Author: K.C. Garrigan
Source: final paper par excellencefor Geology 112, May 1997

Earthquakes and Fire

We all know that earthquakes kill people. Buildings fall down and bury victims under tons of
rubble. The recent M7 earthquake in Iran took more than 2000 lives. Most of those killed were in
small remote villages where they lived in dwellings constructed of mud and bricks. In wealthier,
more developed countries, the use of wood as a building material somewhat reduces the risk of
structural collapse, but greatly increases the potential devastation by fire. In earthquake-prone
areas, builders need to implement earthquake resistant building techniques. The technology to
survive an earthquake exists, the solution is exclusively an issue of financial resource allocation.
After a serious earthquake, even before the victims who died are pulled from the rubble, the
topic of fire suppression is paramount. Rescue attempts are useless if fire is an immediate
concern. The problem with post-earthquake fire control rises where current technology, a
firetruck and working hydrant, is unavailable. Either the technology simply isn't good enough, or
is prohibitively expensive to implement. After a powerful earthquake, the damage to structures
due to ground shaking is something we cannot really control. I contend that damage from fires
may be the most significant earthquake-related economic burden facing modern urban areas such
as San Francisco, Kobe, Tokyo, Shanghai, Manila, and Mexico City. A closer look at San
Francisco, in both the 1989 Loma Prieta earthquake and the great 1906 earthquake, will
emphasize my point in this country. A review of the disastrous 1923 Tokyo earthquake and the
recent 1995 Kobe earthquake are used to reveal the extent that modern, rich, technologically
advanced communities around the globe still have to go to overcome this crisis.
In 1906, it was not the earthquake that destroyed the city of San Francisco, but the
devastating fire that methodically consumed block after block. Fire-fighting equipment in those
days was not comparable to today's equipment, but we still plan to use water to extinguish a fire.
Without water it doesn't matter how big and shiny your new fire truck is. Someone's home is
going to burn. In April 1906, the San Francisco Fire Department did not have water available,
and a large part of the community was totally destroyed. There was no water because the same
earthquake that damaged the buildings man built above ground also destroyed the water
transport pipes man built under the streets. A single broken pipe will dramatically lower water
pressure, with hundreds of smashed pipes. An alternative source of water is the only solution.
Geologists know that earthquakes cause the most damage in areas where structures are built
on unstable soils. Areas with high ground water tables or which were formerly marshes, sand
dunes or landfills are at a higher risk for earthquake damage. These same areas are also at a
higher risk for water mains being broken. This is the classic recipe for disaster. Earthquake
caused small fires rapidly grow into conf lagrations because there is no method to preserve the
water needed for the firefight.
San Francisco's main source of water in 1906 and today is the Crystal Springs reservoir. The
dam is built across the San Andreas fault. The primary pipes that provided water to the city in
1906 were laid due north and buried about three feet deep. The 44-inch wrought iron water pipes
crossed the San Andreas fault numerous times between the reservoir and the city water plant. In
one half mile section the line had over thirty separate failures. A 30-inch line that was placed
south and east of San Bruno mountain was built underground in some areas and built above
ground where it crossed a swampy area near the bay. It failed both below ground where it pulled
apart and above ground where it was knocked of its supports. There is no earthquake safe path
from Crystal Springs to the city of San Francisco. San Francisco is expected to be limited only to
Lake Merced and water from the bay after the next big earthquake.


Author: K.C. Garrigan Source: final paper par excellencefor Geology 112, May 1997
	Earthquakes and Fire
We all know that earthquakes kill people. Buildings fall down and bury victims under tons of rubble. The recent M7 earthquake in Iran took more than 2000 lives. Most of those killed were in small remote villages where they lived in dwellings constructed of mud and bricks. In wealthier, more developed countries, the use of wood as a building material somewhat reduces the risk of structural collapse, but greatly increases the potential devastation by fire. In earthquake-prone areas, builders need to implement earthquake resistant building techniques. The technology to survive an earthquake exists, the solution is exclusively an issue of financial resource allocation. After a serious earthquake, even before the victims who died are pulled from the rubble, the topic of fire suppression is paramount. Rescue attempts are useless if fire is an immediate concern. The problem with post-earthquake fire control rises where current technology, a firetruck and working hydrant, is unavailable. Either the technology simply isn't good enough, or is prohibitively expensive to implement. After a powerful earthquake, the damage to structures due to ground shaking is something we cannot really control. I contend that damage from fires may be the most significant earthquake-related economic burden facing modern urban areas such as San Francisco, Kobe, Tokyo, Shanghai, Manila, and Mexico City. A closer look at San Francisco, in both the 1989 Loma Prieta earthquake and the great 1906 earthquake, will emphasize my point in this country. A review of the disastrous 1923 Tokyo earthquake and the recent 1995 Kobe earthquake are used to reveal the extent that modern, rich, technologically advanced communities around the globe still have to go to overcome this crisis. In 1906, it was not the earthquake that destroyed the city of San Francisco, but the devastating fire that methodically consumed block after block. Fire-fighting equipment in those days was not comparable to today's equipment, but we still plan to use water to extinguish a fire. Without water it doesn't matter how big and shiny your new fire truck is. Someone's home is going to burn. In April 1906, the San Francisco Fire Department did not have water available, and a large part of the community was totally destroyed. There was no water because the same earthquake that damaged the buildings man built above ground also destroyed the water transport pipes man built under the streets. A single broken pipe will dramatically lower water pressure, with hundreds of smashed pipes. An alternative source of water is the only solution. Geologists know that earthquakes cause the most damage in areas where structures are built on unstable soils. Areas with high ground water tables or which were formerly marshes, sand dunes or landfills are at a higher risk for earthquake damage. These same areas are also at a higher risk for water mains being broken. This is the classic recipe for disaster. Earthquake caused small fires rapidly grow into conf lagrations because there is no method to preserve the water needed for the firefight. San Francisco's main source of water in 1906 and today is the Crystal Springs reservoir. The dam is built across the San Andreas fault. The primary pipes that provided water to the city in 1906 were laid due north and buried about three feet deep. The 44-inch wrought iron water pipes crossed the San Andreas fault numerous times between the reservoir and the city water plant. In one half mile section the line had over thirty separate failures. A 30-inch line that was placed south and east of San Bruno mountain was built underground in some areas and built above ground where it crossed a swampy area near the bay. It failed both below ground where it pulled apart and above ground where it was knocked of its supports. There is no earthquake safe path from Crystal Springs to the city of San Francisco. San Francisco is expected to be limited only to Lake Merced and water from the bay after the next big earthquake.