California is frequently struck by earthquakes and the next quake may well be the next Big One. No one knows when the next major earthquake will occur, or what part of the state it will affect. Despite our inability to predict these things, we’ve come a long way in preventing earthquake-related damages and injuries. As the recent quakes in Ridgecrest have shown, seismic retrofitting can work wonders in boosting earthquake resistance of residential structures.
If you haven’t done so already, take the time to prepare your home, yourself, and your family for the next major earthquake event. The following pointers will help you to identify what steps you must take before, during, and after an earthquake in order to reduce injuries and property damages.
Over the past century, engineers have made notable strides in understanding earthquake-triggered damages in buildings. Structural design has evolved to anticipate these failure mechanisms and enable the structures to withstand them. Seismic retrofits have saved countless lives and billions of dollars worth of property over the past few decades. If you’re a homeowner, do your due diligence by preparing your home for the next quake. Start by asking these questions:
Your home may or may not be anchored to the foundation beneath it. This will govern how it behaves when struck by an earthquake. In case the frame supporting the structure is not anchored to the concrete foundation, the earthquake loads can cause it to slide or collapse, causing loss of life and property. A structural engineer can assess your home and determine whether or not it’s properly attached to its foundation. Call us at (877) 704-6765 or email us at email@example.com to discuss your project and receive a free quote.
Cripple walls are short stud walls that create the crawl space beneath a structure. These walls, if left unbraced, may buckle during an earthquake, causing the structure above to shift or fall. To find out if your home is susceptible to this hazard, head to the crawl space and look for cripple walls. See if they have plywood panels or diagonal wood sheathings nailed to their studs. If not, then the cripple walls are not braced to resist earthquakes.
If your home has a room over the garage, the large opening created by the garage door weakens the structure making it vulnerable to seismic forces. Known as a “soft story”, this condition has proven deadly over the past century. If your home has a soft story condition, consult a licensed structural engineer without delay, who will help you in strengthening your home by designing shear panels, hold down anchors, prefabricated shear walls, or a steel moment frame depending on your building’s configuration and budget.
Unreinforced masonry homes are those that are built with bricks, hollow clay tiles, stone, concrete blocks, or adobe. These suffer significant damage during earthquakes, as the mortar holding the masonry units together is not strong enough to resist seismic loads.
California has banned unreinforced masonry from use in structural applications in new buildings before World War II, so if your home predates the war, it may be wise to consult an engineer and find out whether this condition is present. It is crucial to find out if your home has unreinforced masonry that can trigger damage or collapse during an earthquake. Certain parts of newer homes, such as chimneys, may be unreinforced as well; if they are, you can expect them to crumble or collapse when an earthquake happens.
If your home has a water heater, it needs to be braced properly to prevent it from collapsing during an earthquake event. This collapse may lead to broken water pipes and ruptured gas lines causing flooding or fires inside your home. In case the water heater is unbraced, contact a licensed structural engineer to design the appropriate bracing arrangement.
You may have done your best to prepare your home for the next earthquake. But you must also prepare your family for a situation where you may need to take shelter in an underground bunker. In case your home suffers significant structural damage, you may have to spend several days without any outside assistance. Make sure to prepare a survival kit to help you get through this ordeal. It should have at least the following items:
Every family has unique needs, and you should consider yours as you prepare the kit. Are there special mobility needs? Are there infants? What about prescription medications? How will you communicate with your relatives and let them know where you are? Answering these questions is easier and takes less time before an earthquake rather than in its aftermath.
If you’re indoors, stay indoors. It is natural to assume that the building you’re in, or parts of it, may collapse during an earthquake, and you may want to exit the building in search of safety from an earthquake. Unfortunately, many who try to abandon a building get struck by falling debris on their way out. Those who find adequate cover and remain inside, on the other hand, have the best chance of avoiding serious injuries and surviving the ordeal.
If you’re indoors when an earthquake strikes, get away from exterior walls and windows and take cover under a sturdy table or desk. If there isn’t a table or desk near you, cover your face with your arms and crouch in an inside corner of the building. If you’re bound to a wheelchair, find a place away from walls and windows, lock the wheels, discard all detachable items and cover yourself with your arms. Click here for more useful information if you or someone in your family has mobility needs.
If you’re outdoors, stay clear of buildings, trees, power lines, and other items that may fall on you. If driving, pull out of traffic and find a safe spot to stop your vehicle - ideally, away from bridges, overpasses, trees, light posts, and power lines.
In crowded places, panic can spread easily and overwhelm everyone during a natural disaster. People are likely to follow their instincts and rush to the nearest exit, causing deadly stampedes. As mentioned before, trying to escape a shaking building puts you in harm’s way as you run unprotected through falling debris. If you’re in a public place when the ground starts shaking, get away from walls and windows, take cover, and stay there.
Earthquakes often trigger other natural disasters, like tsunamis and landslides. If you’re near an ocean shore when an earthquake strikes, beware of tsunamis - get to higher ground as soon as you can, and monitor local radio stations for alerts. If you’re in a mountainous area, beware of mudslides and stay away from steep slopes.
Ensuring you and your family are safe should be your topmost priority immediately after an earthquake.
Injuries. Once the shaking stops, check yourself for injuries, then tend to those around you if you can. In the process, don’t attempt moving people who are seriously hurt unless they’re at risk of further injury; instead, call for the emergency services for their help. To keep your family from getting hurt by broken objects and shattered glass, wear long-sleeved shirts, long pants, and sturdy shoes. Most importantly don’t panic.
Fires. After the ground stops shaking, fires are the single biggest safety hazard to the survivors and their property. Once you’ve tended to injuries, extinguish any small fires you have access to and remove fire hazards from their vicinity. Unless you are professionally trained to use a fire extinguisher, do not attempt to tackle large fires by yourself and wait for emergency services to arrive.
Gas. Unless you smell gas, assume that the gas lines are fine and don’t shut the main valve off as it may take a long time for the utility to turn it back on. You should NEVER try to turn it back on yourself.
The earthquake’s forces may have damaged your home to a point where a total or a partial collapse is imminent. Unreinforced masonry structures, such as chimneys, may have been weakened and may present an immediate safety hazard. Take a brief look around inside and outside your home and identify conditions such as cracks, sunken foundations, loose masonry and structural members, and stay clear of them. Once the exit way is clear, get your family outside and stay away from buildings, light posts, trees, and anything else that might come crashing down if any aftershocks occur.
Once outside, look out for fallen power lines; check on your neighbors, particularly elderly people and people with mobility needs; keep monitoring local radio stations for updates and instructions, and do not assume that your home is safe to return to until it has been inspected by the competent authorities.
While performing a visual evaluation of damage immediately after a quake may help you avoid imminent hazards, you will not know for sure if the building is safe to occupy or not, nor which repairs are necessary, until a professional assessment has been performed. Your local building department may help, but you will need to hire a licensed structural engineer to inspect the damages and recommend suitable repairs.
Post-earthquake assessments can be grouped into 3 general categories - Search and Rescue Assessment, Safety Assessment, and Damage Assessment.
A Search and Rescue Assessment is done to identify the most critically damaged structures for the sole purpose of directing rescue efforts. It happens immediately after an earthquake and its sole aim is to get the emergency crews to your location if you’re trapped and to get all the trapped people out to a secure location.
Safety Assessments are conducted by local and state building departments, which deploy engineers to inspect buildings in quake affected areas and determine whether they are safe to occupy or not. Such assessments are typically ordered in heavily damaged areas, while occupants of less-affected zones have to request one on their own.
The purpose of a safety assessment is to determine if a building is unsafe to inhabit, susceptible to serious damage because of continuing aftershocks, or it is safe to occupy. Based on these findings, the inspected buildings are issued red, yellow, and green tags, respectively.
Damage Assessments are the comprehensive investigations done to identify all earthquake-induced damages and recommend repairs. Contractors, and even occupants may perform these to evaluate the extent of cosmetic damages; however, only licensed structural engineers may assess a structure’s capability to carry design loads. If a building survives an earthquake, the best course of action is to hire a licensed professional to perform a comprehensive building damage assessment and investigate if any corrective actions are required.