You must already know that earthquakes are trembles or tremors felt on the ground that cause movement in the tectonic plates of Earth and also displacement of the ground. These occur due to the sudden release of energy in earth’s crust, and their magnitude can widely vary. But do you know how often this natural disaster occurs? Geological reports and data reveal that on average there are 14,000 or more earthquakes occurring every year which means 40 earthquakes per day. And these are the earthquakes with magnitudes above 4. An earthquake with its magnitude below 3 is considered as weak and above it is quite appreciable. There are more severe earthquakes, i.e. with magnitude 6 or greater than 6, there are 150 earthquake occurrences every year. Moreover, an earthquake with its magnitude greater than seven can potentially cause severe damage to property and lives.
Globally, approximately 63,000 people lose their lives every year owing to this natural calamity. An even larger number lose their houses either because they didn’t evacuate the place immediately or they didn’t know that there was an earthquake. While a stronger earthquake can shake even the strongest of buildings and infrastructure, man can take precautionary measures by building seismic resistant buildings that can withstand an earthquake without collapsing.
Every building is capable of carrying its weight, and furthermore some weight suspended vertically over it. But an earthquake can cause side to side load over a building that only those buildings can withstand which have been designed keeping these complications in mind. While making your home earthquake proof, these are a few musts that one needs to follow:
Earthquake resilient engineering
During the event of an earthquake, two types of forces are acting on a building that can cause it to collapse or removed from its foundation. These are horizontal and vertical forces. For a house to be considered as earthquake safe, the frame of the house shall allow these forces to pass through them and move towards the foundation of the house. The vertical forces or the uplift forces create an up-down movement and usually even a weak building can tolerate some of these forces without failing. But stronger these forces get, more difficult it becomes for a building to withstand them. Vigorous up and down movement can cause a building to overturn or get raised from its foundation. The horizontal forces have and, even more, drastic effect. These forces are lateral and create a back and forth vibration of the structure of the building weakening the structure. Strong lateral forces produce waves like a pendulum where each swing is longer than the last one, and ultimately the building slides off its foundation. While designing the structure of a building a thorough knowledge about the seismic forces can help in making the building safe.
Another important component of earthquake resilient construction is building a stronger frame that can transfer the seismic forces to the foundation of the housekeeping the house intact. It can be achieved by creating a continuous load path. A continuous load path uses some building materials like metal connectors, fasteners, nails and more which can tie the building together and provide strength to it. Hiring a licensed engineer at the time of construction or for inspection can help you build a safer home.
Solid foundation and Anchoring
A concrete foundation is of utmost importance while trying to build an earthquake-proof house. Building materials like bricks cannot provide the required strength for withstanding an earthquake. Housing foundations can be of many types- poured perimeter foundations, unreinforced masonry foundations, slab foundations and post and pier foundations. While building a new house strength of the organization shall be checked for and if you are getting your already built house inspected then a strengthening upgrade is a must thing. Anchoring also plays a vital role in providing strength and durability to the structure of the house. Unless there are enough anchor bolts fastened every 4-6 feet in the sill plate, there will be a risk of the house sliding off its foundation. To check for anchor bolts, look into the crawl spaces in your house and ensure that your house is well anchored.
If you are living in a house that was constructed a long time ago and you want to make it resilient to seismic forces without rebuilding it entirely then retrofitting is the smart choice. Obviously, before you decide what changes you need to make to your old house you need to get it inspected by a licensed engineer or a retrofit specialist. One must consider hiring a specialist while the process of earthquake proofing is going on. The very basic aim retrofitting seeks to achieve is making your home less prone to damage and preventing it from getting displaced from its foundation. In this process, foundation bolting is usually the first thing to do. It strengthens the structure of your house by adding bolts through the wooden surface above the foundation. These bolts help in improving the connection between the wooden frame and the concrete foundation so that the house doesn’t slide, rack or overturn from the foundation. Cripple wall bracing is another part of retrofitting. In this, plywood is attached firmly to the wall framing that braces the structure of the house and prevents side to side swaying and collapsing of the building. Cripple wall collapses are often a reason of why a house gets damaged during an earthquake. But cripple wall bracing can make the house strong enough to tolerate a few shocks as they work as shock absorbers.
Furniture and Fittings
All the furniture and fixtures in your house shall be such that when an earthquake hits, the furniture stays intact and doesn’t cause injuries to the people living in the house. The earthquake vibrations often cause overturning of furniture and knocking off anything hung on the walls. The critical thing is to make sure that there are not any pictures or wall hangings over your bed. If there are any, relocate them to someplace else. All the fixtures shall be tightly attached, and the lights and fans on the ceiling should also be fixed correctly. Make sure that devices like television, music player, etc. have a strong, solid base beneath them which can provide enough support to their weight. While Earthquake was proofing your house it is strongly recommended to buy some good quality earthquake safe straps and install them on your bookcases, cabinets, and shelves, big screens, and furniture.
Other safety measures
Other than collapsing of the house, some other elements can also become hazardous or even fatal during an earthquake. The electrical wiring inside the house is one of them. You should check for any poor installation and fix it immediately if found any. Utility lines can also pose a threat to lives and should be fixed by a professional. Make sure that the gas pipelines in your house are flexible so that they don’t break due to earthquake vibrations. The seismic forces can tear the gas pipeline causing a fire or an explosion that is extremely dangerous for your property and you. Hence, use flexible connection pipes for the gas line, hot water, gas furnace, and stove. During an earthquake stay away from the electrical sockets and do not light a matchstick or try to start a fire as it can be extremely dangerous. Also, the gas pipe should automatically shut down during an earthquake so that there is no leaking of gas and a potential fire.
A safety drill, especially with kids, can help you in staying prepared for such a situation. Decide on a location beforehand where you can hide inside the house during an earthquake. It can be under the bed or a strong table or a desk. As soon as the vibrations cease to evacuate the building immediately and stand away from any electrical poles, glass windows or trees.