In San Francisco, water and gas pipelines are separated by valves so that areas can be isolated if one segment breaks. Cost, of course. More sturdy structures are much more expensive to build. So communities must weigh how great the hazard is, what different building strategies cost, and make an informed decision. In , the Hayward Fault erupted in what would be a disastrous earthquake today.
Since the fault erupts every years on average, East Bay residents and geologists are working to prepare for the inevitable event. Skip to main content. Search for:. Describe the features that make a structure earthquake safe. Describe how to protect a person or household in earthquake country. At Sanctuary Villas in Burwood, 21, 1. When a an earthquake hit in February , the raft protected the homes from serious damage — only minor repairs were needed — while several buildings in the surrounding areas had to be demolished and rebuilt.
At Streamside Court in Woolston, 49 bungalows built on a 1m thick stabilised gravel raft in escaped damage when two earthquakes — in February and June caused liquefaction of the underlying 9m of saturated loose sand and soft silts.
While buildings in the area collapsed, only minor cracking of concrete bases and opening of kerb joints was seen on the estate. A partly-built 0. The finished raft also protected the completed building during subsequent earthquakes in June and December that year. Buckling of Piles: Pile foundations are embedded deep into the ground because of the soil support.
But if the soil is not strong, the foundations buckle which lead to collapsing of the structure. Spreading of ground: The soil starts to move in a downward direction due to the liquefaction. Slopes starting from an angle of 3 degrees are prone to lateral spreading.
The effects of soil liquefaction on the built environment can be extremely damaging. Buildings whose foundations stand directly on the sand, which liquefies, will experience a sudden loss of support.
The irregular settlement of ground may also break underground utility lines. The upward pressure applied by the movement of liquefied soil through the crust layer can crack weak foundation slabs and enter buildings through service ducts, and may allow water to damage the building contents and electrical services. Bridges and large buildings constructed on pile foundations may lose support from the adjacent soil and buckle or come to rest at a tilt after the earthquake induced shaking.
Most of the structures in the affected areas were tilted and sank into the sediments, even while they remained intact. The shifts in soil destroyed water, sewer, and gas pipelines, crippling the utilities and infrastructure.
With such a long-lasting earthquake, the structures continued to sink and tilt as the shaking continued for several minutes. The younger sediments, and especially the buildings constructed on the new landfill ground, were much more vulnerable Ashford, Liquefaction caused significant damage to the Tokyo Bay coast which was located far away from the epicenter.
The town was built on a land filled area in the s. Soil tests later revealed that the soil in Urayasu shows less resistance to Liquefaction.
Stay away from where glass could shatter around windows, mirrors, pictures, or where heavy bookcases or other heavy furniture could fall over. Drop to the ground, cover your head and neck, and hold on until the shaking stops. Wait until the shaking stops and then check if others are hurt. If you leave the building after the shaking stops, use the stairs. Never use the elevator. If you are outside, move away from buildings, lights, power lines electric lines and trees.
Drop and cover your head! Find out what you should pack in your earthquake supply kit , which has more items than a simple first aid kit. Your home also may be vulnerable to serious structural damage if it was built before Earthquake safety preparation requires your understanding of the potential structural threats to your home in case of an earthquake. CEA offers earthquake home insurance premium discounts for houses and mobilehomes that have been properly retrofitted.
With nearly 16, known state faults and more than active faults, California is earthquake country. Most of us live within 30 miles of an active seismic risk. Scientists continue to find new faults. Find out about faults in your area by visiting the CEA risk map for each county. This information will help you create an earthquake precaution checklist. California Office of Emergency Services MyHazards can help you find out if the area where you live or work is prone to earthquake-induced landslides.
Our affordable earthquake insurance policies let you select the coverage that fits your budget. CEA earthquake insurance is easy to buy.
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