Many older homes built before 2000 do not meet current earthquake safety standards. Unless your property was newly constructed, it is wise to consider retrofitting your house to make it more resistant to seismic activity.
Throughout history, destructive earthquakes have severely damaged cities, residential properties, and people worldwide. In response, organizations like Earthquake Country Alliance aim to educate homeowners on protecting themselves and their investments from earthquake hazards.
If not properly strengthened, homes deficient in building code compliance risk becoming uninhabitable after seismic events. Homeowners may incur tens of thousands in repair costs before moving back in or renting out fixed properties.
To prevent such outcomes, the following are some guidelines for designing an earthquake-resistant house from foundation to roof.
What Is the Frequency of Earthquakes?
Earthquakes occur frequently around the globe. Estimates show over 55 tremors take place daily worldwide. However, the vast majority of the approximately 20,000 annual quakes are quite minor and often go undetected.
Only about 16 significant earthquakes per year register above a magnitude seven on the Richter scale. These major seismic events have the capability to cause extensive harm and should not be taken lightly, given their magnitude and potential for widespread damage.
While smaller earthquakes are common, those over magnitude 7 deserve special consideration due to their increased strength and resulting hazards.
Which Areas Are More Prone to Earthquakes?
While mountains themselves, such as those around Alaska and San Luis Valley, don’t directly induce earthquakes, they play a significant role in influencing seismic activity.
Earthquakes tend to be more pronounced due to the amplification of seismic waves by valleys and slopes. Moreover, the presence of mountains can exert additional stress on specific tectonic plates, increasing the likelihood of seismic events.
It’s crucial to recognize that both earthquakes and mountains result from tectonic forces affecting the Earth’s crust.
It’s prudent for residents in mountainous areas to exercise extra caution, as emphasized by Team North Star. What you need to note is that the earthquake risk in places like Durango is relatively low compared to other mountainous regions like San Luis Valley, Colorado.
But, if you’re considering purchasing a home in a mountain city such as Durango, seeking guidance from experienced Durango realtors can be invaluable in addressing real estate concerns specific to these areas.
6 Advanced Measures You Can Take While Building an Earthquake-Proof House
#1 Strengthening Your Home’s Foundation
The foundation is meant to withstand outside forces and support the weight of the home above it. However, changes over time can cause the foundation to become compromised.
Shifting soils or added weight may result in cracks or other damage to the foundation structure. This is especially concerning in areas prone to seismic activity, where intense shaking could further weaken an already strained foundation.
Foundation issues threaten the integrity and safety of the entire home. Leaving foundation problems unaddressed is risky, and expensive repairs may be required if damage spreads.
It is advisable to have a structural engineer evaluate the foundation and recommend professional reinforcement methods if needed. Techniques like mud jacking, underpinning, or lifting, can bolster the foundation to reduce the potential for serious earthquake damage.
Another option for seismic stability for an earthquake-resistant house is a base isolation system. This involves incorporating flexible materials like rubber and lead into the foundation design. This allows the home to sway more freely without transmitting the full force of ground shaking throughout the structure during an earthquake. By mitigating vibrations at the base, base isolation can better protect the foundation and superstructure.
#2 Bolting the Frame to the Foundation
During the foundation assessment, the structural engineer may recommend bolting the home’s frame to the reinforced foundation. Known as foundation bolting or bracing bolting, this involves securing the wooden structure directly to the concrete base.
In older homes especially, a mudsill piece of wood typically rests on top of the foundation. Unbolted, the mudsill could allow seismic forces to cause the entire home to slide off the foundation. Foundation bolting counters this risk by fastening down the mudsill layer with anchor bolts embedded into the reinforced concrete.
This added connection between the foundation and wooden framing provides extra protection. By tying the home more rigidly to its stable base, foundation bolting helps reduce the chances of structural separation or shifting during earthquake ground movements. It reinforces both the foundation repair below and the home’s superstructure above.
#3 Using Seismic Dampers
Similar to the shock absorbers used in automobiles, seismic engineers employ damping systems to reduce the damaging effects of earthquake vibrations on buildings or houses. Just as shock absorbers lessen impact forces on a car, these techniques help absorb and diminish the magnitude of seismic shockwaves.
According to Connor Daly Construction, there are two primary damping methods utilized, namely vibrational control devices and pendulum power.
Vibrational control devices involve strategically placed dampers between columns and beams at each level of the structure. Each damper contains piston heads inside a cylindrical chamber filled with thick silicone oil.
During an earthquake, the vibrational energy is transferred into pushing and pulling the pistons against the damping fluid. This conversion of energy into heat dissipates the force of the oscillations before they can transmit through the house.
Another common approach is pendulum power, especially for tall skyscrapers. Engineers suspend an enormous ball from steel cables connected to a hydraulic mechanism at the tower’s apex.
As the house starts to sway in quake motions, the pendulum ball swings in the opposite direction to counteract lateral forces and stabilize the structure. Like seismic dampers, these pendulum features are tuned to match and negate the home’s natural Period in response to earthquake ground shaking.
Together, vibrational control devices and pendulum damping systems function much like automotive shock absorbers to reduce the magnitude of seismic shockwaves.
#4 Reinforcing Windows Against Breakage
One way to improve an earthquake-resistant house safety is by reinforcing existing windows. Ordinary window glass poses hazards if shattered by high winds or debris during storms. However, upgrading to reinforced glazing options offers protection.
Two viable solutions are the application of safety film and laminated glass installation. A safety film consists of a durable transparent coating applied to window surfaces. When stressed, the film helps bind glass shards together, limiting the risk of injuries from broken panes.
Laminated glass takes a multi-layered approach. It bonds several thin glass sheets with an inner polyvinyl butyral interlayer. This lamination distributes forces across the assembly, preventing complete breakage even if an outer pane cracks or chips.
#5 Installing Shear Walls
One of the greatest dangers during an earthquake is shear forces, which can cause portions of a home to move sideways and potentially lead to structural failure under intense lateral pressures.
A proven solution is to install shear walls, typically made of steel cross-bracing, to resist these horizontal forces. The crisscrossing braces cause the wall to act as a single unit when shifting occurs, reinforcing the structural integrity.
While ideal for new construction, shear walls can also strengthen existing homes through seismic retrofitting.
Engaging the services of a seasoned seismic retrofit contractor is crucial for ensuring the proper implementation of this protective measure. These professionals possess the expertise to assess your home’s unique needs and skillfully integrate shear walls into the existing structure.
Applying stiff vertical walls without openings in vulnerable areas like stairwells and elevators improves a building’s ability to withstand earthquake impacts. The walls provide crucial support to resist shear stresses.
Properly incorporating additional shear walls utilizing modern bracing techniques can significantly boost a custom home’s chance of surviving powerful seismic activity with minimal impacts.
#6 Considering Levitation
The levitation technique is a unique seismic safety measure that entails raising a house off the ground during an earthquake.
Traditionally, the house sits on a deflated airbag. In the event of seismic activity, a compressor injects air into the bag, lifting the house several centimeters above the ground. This innovative approach effectively reduces the impact of the earthquake on the structure.
Levitation technology is commonly employed in standalone houses, providing them with a distinctive level of protection during seismic events.
In summary, addressing seismic safety in homes is vital, particularly for older structures.
Essential strategies include seismic retrofitting, reinforced foundations, and advanced damping systems to mitigate potential damage. Reinforcing windows and exploring innovative techniques like levitation can enhance home safety during seismic events. A proactive approach to earthquake preparedness is crucial for safeguarding property and peace of mind.
