| Earthquake Awareness and Preparedness |
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Seismic Retrofitting vs. Risk Mitigation
Observations from the 1994 Northridge Earthquake and 1995 Kobe Earthquake demonstrated that the loss
of property, level of structural damage, time and efforts required for repair and recovery, and cost of repairs,
as well as injuries and damage to contents are significantly reduced in buildings where seismic retrofitting
of the structural system and risk mitigation of the nonstructural components and home contents have been
made. Seismic retrofitting measures are expensive and would require hiring a professional engineer and
a building contractor. However, risk mitigation measures are simple enough to be done by the
homeowner, where commercial kits are inexpensive and available in hardware stores and online stores
like Amazon. Pros and cons of seismic retrofitting versus risk mitigation based on recent earthquake
reconnaissance reports are discussed below, after which a conclusion has been made!
Observations from the 1994 Northridge Earthquake and 1995 Kobe Earthquake demonstrated that the loss
of property, level of structural damage, time and efforts required for repair and recovery, and cost of repairs,
as well as injuries and damage to contents are significantly reduced in buildings where seismic retrofitting
of the structural system and risk mitigation of the nonstructural components and home contents have been
made. Seismic retrofitting measures are expensive and would require hiring a professional engineer and
a building contractor. However, risk mitigation measures are simple enough to be done by the
homeowner, where commercial kits are inexpensive and available in hardware stores and online stores
like Amazon. Pros and cons of seismic retrofitting versus risk mitigation based on recent earthquake
reconnaissance reports are discussed below, after which a conclusion has been made!
Risk Mitigation
Risk mitigation measures are simple techniques to secure nonstructural components and contents of the
home to the studs of the interior walls or floors in order to reduce the risk to lives and investments, 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. A study from the University of California in Los Angeles demonstrated that 55% of the injuries
during the 1994 Northridge Earthquake were caused by unsecured building contents that were overturning
like bookcases, or falling like televisions, pictures, mirrors, and heavy light fixtures. Therefore, you should:
Risk mitigation measures are simple techniques to secure nonstructural components and contents of the
home to the studs of the interior walls or floors in order to reduce the risk to lives and investments, 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. A study from the University of California in Los Angeles demonstrated that 55% of the injuries
during the 1994 Northridge Earthquake were caused by unsecured building contents that were overturning
like bookcases, or falling like televisions, pictures, mirrors, and heavy light fixtures. Therefore, you should:
 | Secure anything in your home that is tall and heavy enough to hurt if it falls on you, using special | |
| furniture straps such as earthquake straps or nylon straps. | ||
| Secure fragile and expensive objects enough to be a significant loss if they fall, using removable | |
| non-damaging adhesives such as Quake Hold or Museum Wax. | ||
| Secure gas appliances (e.g. dryers, stoves, ovens, furnaces) with anchors to the floor or wall studs | |
| and replace rigid pipe connections with flexible (corrugated) stainless-steel gas connectors. | ||
| Water heaters are of special concern and should be braced to the wall studs or masonry wall with | |
| two heavy-gauge metal straps (plumber’s tape is no longer recommended) and lag screws near the top and bottom of the tank. |
Seismic Retrofitting
Seismic retrofitting are measures taken for older homes to meet the current building codes by improving
their structural integrity to withstand earthquakes with no or little structural damage, which will ensure life
safety, home safety and help in returning families quickly back to their normal life style. Earthquake
damage to buildings is influenced by construction materials, foundations condition, cripple walls being
unbraced, soft story in the first floor due to large openings without effective bracing, year built, and number
of stories. Seismic retrofitting the structural system of a home is the responsibility of the homeowner,
which can be a complex process that typically costs between $3,000 to $10,000 or more according to
building size and number of floor levels, homes built on steep hillsides, homes with finished basement or
cripple walls, and homes with rooms over garages. You should know that:
Seismic retrofitting are measures taken for older homes to meet the current building codes by improving
their structural integrity to withstand earthquakes with no or little structural damage, which will ensure life
safety, home safety and help in returning families quickly back to their normal life style. Earthquake
damage to buildings is influenced by construction materials, foundations condition, cripple walls being
unbraced, soft story in the first floor due to large openings without effective bracing, year built, and number
of stories. Seismic retrofitting the structural system of a home is the responsibility of the homeowner,
which can be a complex process that typically costs between $3,000 to $10,000 or more according to
building size and number of floor levels, homes built on steep hillsides, homes with finished basement or
cripple walls, and homes with rooms over garages. You should know that:
| It is cheaper to retrofit now than to repair after an earthquake. | |
| Recent cost/benefit studies have shown that for every $1 spent in seismic retrofitting measures, | |
| there is a long-term savings of $3 to $16 according to the Institute for Building and Home Safety (IBHS). | ||
| An appropriate seismic retrofit will reduce earthquake damage and save money. A partial | |
| improvement of the weakest areas of the home would also be valuable if done one-step at a time, starting with safety-related improvements rather than property-protection improvements. | ||
| The earthquake damage may be extensive enough to require demolishing the entire home. | |
| Performing structural repairs to the home after an earthquake would be very expensive because of | |
| the shortage in the available building contractors and structural engineers in the impacted area, as a result of the sudden high demand for their services. |
Conclusion
Most of single-family homes in the United States are the type of flexible timber frame houses that perform
relatively well in frequent minor-to-moderate earthquakes. In the meantime, it is a well-known fact that
minor-to-moderate earthquakes are more frequent and most-likely to occur than major earthquakes.
Previous earthquake reconnaissance reports demonstrated that buildings subjected to minor-to-moderate
earthquakes experienced less structural damage and more damage to nonstructural components (e.g.
utility connections and lighting fixtures) and home contents (e.g. furniture and appliances). The dollar value
of such damages can add up quickly in an era of high-tech devices, a fact which takes on added
importance if the devices are not covered by homeowners insurance or are covered by earthquake
insurance which often has a high deductible. Actually, billions of dollars were lost during Northridge
Earthquake due to this type of damage which could have been prevented in advance through the
above-mentioned risk mitigation measures.
Therefore, it can be concluded that risk mitigation measures of nonstructural components and home
contents should be performed before the next earthquake, whether you retrofit your home or not.
Most of single-family homes in the United States are the type of flexible timber frame houses that perform
relatively well in frequent minor-to-moderate earthquakes. In the meantime, it is a well-known fact that
minor-to-moderate earthquakes are more frequent and most-likely to occur than major earthquakes.
Previous earthquake reconnaissance reports demonstrated that buildings subjected to minor-to-moderate
earthquakes experienced less structural damage and more damage to nonstructural components (e.g.
utility connections and lighting fixtures) and home contents (e.g. furniture and appliances). The dollar value
of such damages can add up quickly in an era of high-tech devices, a fact which takes on added
importance if the devices are not covered by homeowners insurance or are covered by earthquake
insurance which often has a high deductible. Actually, billions of dollars were lost during Northridge
Earthquake due to this type of damage which could have been prevented in advance through the
above-mentioned risk mitigation measures.
Therefore, it can be concluded that risk mitigation measures of nonstructural components and home
contents should be performed before the next earthquake, whether you retrofit your home or not.