This article is a bit dated: written several years ago. It has been lightly updated .
Preparing for the Big One. - An ounce of prevention
is worth a pound of cure.
By Bruce Conway - www.lightwatcher.com
Many residents of the Pacific Northwest remember a seismic event that happened in May of 1996. Some felt it gently rock their homes. This local tremors resulted from the distant Duval Earthquake. As earthquakes go, the effect of the Duval quake was mildly felt in the San Juan Islands. My wife Jen thought that I was behind her, gently rocking the chair; I wasn't. At the same time, I experienced a rumbling sound and then a slight dizziness. Attributing these sensations to commercial trucks passing our home on Tucker Avenue, I went back to the book I had been reading. Within a few moments the TV was abuzz was with news of the 5.3 magnitude Earthquake.
This past spring I spent two frightening minutes riding out another local quake, in a doorjam shared with our local Red Cross official. This one was a 5.4.
Some newcomers to the Pacific Northwest aren't
aware that they now live in an area prone to earthquakes and volcanic
activity. Many people fleeing the dangers of California and elsewhere
are shocked to find that this region is more seismically dangerous
than the State they departed. Seismic events happen less frequently
here, but when they do occur, they can be more devastating than
their southern California counterparts.
In 1909, Orcas and Stuart islands experienced an earthquake of
6.0 on the Richter Scale. In 1920 San Juan Island was struck.
Olympia was rocked by a 7.1 quake in 1949 and damages were extensive.
Seattle was struck in 1965 by a magnitude 6.5 which killed seven
people. In 1976 Saltspring Island, BC had a 5.1 quake (The Duvall
quake epicenter logged a 5.3). Our local tremors are classified
as deep quakes, potentially the most damaging.
Washington State has an average of roughly
one thousand quakes per year. Most are small; in the 1-2 magnitude
range. Seismologists consider these minor tremors to be the precursors
to a much greater seismic events. There is no other terrestrial
force of nature that commands such destructive power. Even tornadoes
pale by comparison when compared to the immense power of a major
earthquake.
Mt. Raineer, an "active" volcano, went off most recently
in 1846. In 1980 Mount St. Helens erupted, rocking the region,
and spreading thick blankets of ash hundreds of miles to the east
and North.
The second greatest quake ever monitored was the "Good Friday" quake of 1964 in neighboring Alaska. It measured 9.2 on the Richter Scale. It unleashed the power of roughly 25,000 Hiroshima atomic bombs. The resulting damage was almost inconceivable. To visualize a quake of this magnitude, nearly defies one's abilities. Some of us may remember photographs of the Alaskan quake. Autos resting atop garages, land deformed and broken, buildings reduced to debris. Witnesses reported waves of land rolling at great speed, turning over the landscape with colossal force. New bays formed as old ones drained. Tsunamis radiated outward.
Tsunami waves are often caused by undersea seismic activity, and have occurred in this region. These giant waves flood areas close to sea level, causing severe damage. The 1964 Alaska quake sent a tsunami wave crashing into Crescent City, CA, killing twelve people. A 27' Tsunami is believed to have washed over the south end of San Juan Island sometime in the recent geologic past. Dr Atwater also stated in a previous article in the Wall Street Journal: "... a massive tidal wave inundated what is now part of downtown Seattle ...about 1000 years ago."
A frightening question must be asked: Is it possible for us to experience a truly devastating quake here on San Juan Island.? The answer is an emphatic YES! It can happen, because it has happened.
Scientists Brian Atwater of the U.S Geologic Survey and John Adams of the Geologic Survey of Canadian have determined that a quake measuring an estimated 9.0 did strike this area on January 26, 1700 at 9 P.M. The event was large enough to send a tsunami all of the way to Honshu, Japan.
If quakes of this magnitude have happened in the recent geologic past, they will happen again. Experts insist that large quakes will occour here in the near future and implore residents to prepare for the consequences . Seismic scientists and volcanologists agree; the Pacific Northwest is due for major earthquake activity. Experts in British Columbia estimate the odds of a major earthquake (7.0 and above) to be 100% within our lifetimes.
To quote Roy D. Hyndman Ph.D., a senior scientist at the Pacific Geoscience Center of the Geologic Survey of Canada, and author of Giant Earthquakes of the Pacific Northwest (Scientific American, Dec., 1995), "The next great quake in Cascadia will generate extremely large seismic waves, lasting for as long as several minutes. After the shaking ceases, most coastal sites will be two meters lower and five to ten meters seaward of where they started."
The Geological Society of America describes San Juan County as "... a folded sequence of sub-parallel thrust faults." In lay terms: An area of great seismic movement caused by opposing faults.
When the next big one hits, it will likely remold our shorelines and cause landslides. Homes built prior to recent earthquake oriented building codes risk the greatest danger. Those who reside on waterfront property are especially vulnerable. If we think that property and boundary disputes are frequent now, think about what it will be like after a 7.5 quake shuffles the deck.
Experts estimate that most homes will be isolated from police and medical attention for days or weeks following a major seismic event. We will be reliant on our own resources, and those of our neighbors for days or even weeks. If a major quake happens during the cold months, house fires started from overturned woodstoves will compound the damages. Roads will be broken and shifted in height making auto traffic impassable. Water, sewage and electricity will stop immediately as the result of broken pipes and conduits.
The devastating Kobe, Japan quake taught us many things about large quakes. One major revelation was that the big quakes generate strong electromagnetic pulses that damage or destroy electronic devices, just like the ELM pulse that accompanies an atomic detonation. Only electronics that are heavily shielded, such as military hardware will be safely protected.
If one ponders the likelihood of a major quake, and our virtual isolation from mainland emergency services, one sees the importance of planning and preparation. Those who have experienced heavy seismic activity know the importance being prepared, and don't need convincing. Newcomers seldom think about the local seismic factors. It only takes one experience to make a believer out of the most skeptical, but then it is usually too late.
I was stuck for six weeks by the Mt. Pinatubo Eruption in Manila, Philippines in 1991. The seismic activity went on days before the eruption and for weeks and months afterward. The airports closed for nearly a month. The Subic Bay and Angeles U.S. Military bases were literally flattened under the weight of wet ash. And "lahar." The television and radio stations were destroyed, so we lacked news of the emergency. All phones were dead. The cities water and sewage systems plugged up with the thick gray ash. After the worst of the eruptions and quakes, tens of thousands of refugees poured into the already besieged city, vastly overloading its ability to cope.
My father, having experienced revolution, typhoons and other disasters while running his computer company in the Philippines was prepared. We had generators, a protected water storage tank, and a well supplied commissary on premises. Dad also had purchased a great deal of rice foe just such an emergency. We were better prepared than most. Dad's business was up and running quickly after the disaster.
When faced with the possibility of a large
seismic event, most people tend to resign themselves to the inevitable,
doing little or nothing to prepare themselves. This "head
in the sand" approach is a fatal mistake. Experts agree that
education, preparation and advance planning greatly reduce potential
earthquake damage and loss of life. As most governmental agencies
are aware of the earthquake potential of this region, there is
much information available detailing steps to preparedness.
While there has been a good deal of legwork done on a San Juan Islands comprehensice disaster preparedness plan, it's reliance on mainland resources after a disaster ensure that it will not be sufficient in the days and weeks following a truely devastating natural disaster. Former head of the local emergency preparedness team, Chris Destafany, made this statement in a phone interview two years ago: "While the comprehensive emergency plan exists, it is the individual emergency preparedness plans that will make the biggest difference to islanders." He went on to note that "Having a personel emergency kit and a disaster plan would be of the greatest benefit in the initial days and weeks following a large natural disaster." His logic was this: If we are hit hard, so will the mainland, and this is where the majority of the emergency services will be focused. and as well as a Red Cross office in Anacortes and local contacts.
Though this data varies slightly from source to source, the following lists the basic concepts
Quake Proofing
In earthquake prone areas such as California, residents are keenly
aware of the likelihood of quakes, and take numerous precautions.
Quake proofing their homes is a logical first step.
1. Take a good look at your home with an eye tuned for
earthquakes. Think of it as a boat at sea. Or ...
2. Imagine it shaking several feet from side to side, up
and down. In a 6.0-7.0 quake, household furnishings begin to wander
around the rooms. Bookcases fall, TV's and electronics fall to
the floor and bounce around the room. The water heater breaks
loose from its corner and rolls around the rooms, crashing through
walls and smashing everything in its path. Glass flys from broken
windows, brick walls tumble.
Now, Imagine these furnishings glued, velcroed, strapped and screwed
into position.
It has been shown that a couple of hours of quake-proofing can significantly reduce quake damage in a home. Water Heater straps anchor bolted to wall studs keep it in position, saving the water inside for later consumption. Bookshelves are bolted in place. Expensive electronics are protected with foam and velcro. When a quake hits, most furnishings stay in place. Damages are reduced. Fires don't start.
Be Prepared
Create survival kits and put them in easy to reach places.
A survival kit consists of;
1. a well supplied first aid kit
2. food and bottled water
3. Clothing, bedding, boots
4. Tools, self defense, shelter
The following is a brief description of
the effects of a magnitude 7.5 quake, courtesy of the Washington
State publication
"To Survive in Earthquake Country."
· Loud sounds like the rumbling of a
heavy truck may precede the quake.
· The ground will shake and roll, perhaps for thirty seconds
or longer, giving the sensation of walking or standing on a ship
in rough weather.
· The ground surface may rupture and sections may rise
or fall twenty feet or more.
· Sandy and silted soils may liquify, turning into quicksand
(swallowing homes in seconds). There will probably be landslides
in hilly areas.
· There will probably be extensive structural damage (to
homes and local infrastructure).
· Chemicals, fuels and other hazardous materials may cause
fires and release toxic clouds from damaged facilities.
· Tsunamis (a series of giant ocean waves) may strike coastal
areas.
· Fire, police and medical personnel will be overwhelmed
by the demand for their services.
· People will be injured and die.
· Buildings will collapse, trapping people and leaving
others homeless.
· People may be separated from their family, friends and
neighbors by collapsed roads, bridges and phone lines.
· People may have to survive without additional food, water,
shelter and utilities for several days.