Earthquake Preparedness in California

The United States Geological Survey (USGS) predicts that California has a 99.7% probability of having an earthquake magnitude of 6.7 during the next 30 years. Natural disasters such as the 2010 Haiti Earthquake and the 2011 Japan Earthquake are wake-up calls for Californians to develop an earthquake disaster management plan to ensure home safety through seismic retrofit and risk mitigation of home contents, while re-considering earthquake insurance. Earthquake preparedness also requires basic knowledge on the factors influencing earthquake damage to your home. Other earthquake information, tsunami information, and emergency preparedness in California can be found in another article at http://seekyt.com/california-earthquakes.

Earthquake Damage

Recent earthquakes including the 1994 Northridge Earthquake and the 1995 Kobe Earthquake demonstrated that earthquake damage to you home is influenced by building materials, anchor bolts not securely connected to the concrete foundations, soft story in the first floor due to large openings without effective bracing, unbraced crawl space, year built, and number of stories. Unreinforced masonry and non-ductile reinforced concrete are building materials that are no longer allowed to be built in California because they have a poor performance during earthquakes and may be heavily damaged, if not retrofitted. Wood construction, ductile reinforced concrete construction, and steel frame construction generally perform better and are less likely to be damaged.

Seismic Retrofit to ensure Home Safety

You should seismic retrofit your home if it is built of unreinforced masonry or non-ductile reinforced concrete; or if you live within 15-25 miles from active fault lines or within areas of liquefaction susceptibility shown on USGS maps (refer to the article mentioned in the first paragraph), regardless the construction material. If you live within 25-50 miles from active fault lines and your home is constructed before the 1980’s, you probably need to retrofit it. Seismic retrofit is your own decision at your own risk according to your financial situation as it may be costly. However, the best return on the investment of seismic retrofit efforts is to be addressed one step at a time as follows:

Step #1: Upgrading the anchor bolts to 3/4 inch diameter spaced at 4 feet with large and thick square washers to secure the anchorage of the sill plate to the concrete foundations. This upgrade costs $250 to $5,000.

Step #2: Bracing the cripple walls using 3/8 inch structural grade plywood panels on the inside surface of the crawl space extending from the sill plate to the base of the floor joist and adequately nailing them to the studs. The cost is $500 to $2,500.

Step #3: Bracing the walls of the soft story using steel members or strengthening them using specially-detailed plywood panels. The cost may exceed $5,000.

Step #4: Anchoring the walls and masonry chimney using metal straps to the structural members of the floors and roof. The cost is $2,000 to $12,000.

Risk Mitigation of Home Contents

A study at the University of California in Los Angeles demonstrated that 55% of the injuries during Northridge Earthquake were caused by falling furniture or objects while only 1% of injuries were caused by structural damage and other injuries were due to people falling or behaving dangerously! The study stated that many of these injuries could have been prevented through simple actions taken before the earthquake. Risk mitigation measures are simple techniques to secure the contents of your home (e.g. tall and heavy furniture, fragile and expensive objects, kitchen appliances, and water heaters) to the studs of the interior walls or floors using inexpensive hardware tools and materials found in hardware stores. Items in the garage shall also be secured to reduce damage to vehicles. Such self-mitigation techniques can be undertaken by homeowners as they are simple to explain and require no special expertise, materials or tools to implement. Therefore, you should mitigate the contents of your home whether you seismic retrofit it or not.

Earthquake Insurance

You have worked hard to secure your piece of the American Dream to become a homeowner. Your assets and investments made in personal belongings may be at risk when an earthquake hits your home as it will have some sort of earthquake damage. In the meantime, California home insurance does not cover earthquake damage to your home, home contents, or personal belongings. However, it covers other kinds of damage caused by earthquakes, such as fire and water damage due to burst gas and water pipes. Your vehicles are only covered under the comprehensive part of the auto insurance policy. Therefore, most of the property damage caused by an earthquake will end up being paid for by you, along with other personal debt. How do you plan to protect your assets and investments from the costs of destructive earthquakes? California earthquake insurance is an option for effectively managing these potential costs. Earthquake insurance premiums differ widely by location, insurance company, and the construction material of your home. Older buildings cost more to insure than newer ones. Wood frame construction benefit from lower insurance rates than unreinforced masonry homes. According to California Department of Insurance, 33% of homes had earthquake insurance coverage in 1996 when the devastating Northridge Earthquake was still fresh in people’s minds, but in 2006 only 12% of homes maintained the coverage. Recent earthquakes of 2010 in Haiti and 2011 in Tohoku Japan may influence Californians’ decision to reconsider buying earthquake insurance, especially if they did not seismic retrofit their homes.