Quakes don’t kill, unsafe buildings do


Photo: Hong Sar/Mizzima

Every good Boy Scout learns – be prepared. The lesson holds true for earthquakes in Myanmar.

As Mizzima pointed out in an earlier story about family preparedness for earthquakes (see here), there is a list of things to do and routines to follow before and during an earthquake.

In addition, geology, building codes, home safety and personal preparedness all play a role in helping minimize deaths or injuries, and the level and cost of overall earthquake damage.

What can you do?

Awareness and knowing what to do are important when an earthquake strikes.

But what can you do on a practical level to make sure your home and family are safe in terms of the location and construction of the building you live in, and the way you have distributed furniture and other items within a home or workplace?

After all – quakes don't kill, unsafe buildings and unsecured furniture pose the main threats, as has been proved again and again.

So what do you need to do specifically on a practical level?

Minimizing earthquake risk is possible in a new building by designing and constructing it with earthquake resistant features.

Depending on when and how your home was designed and built, the structure may have weaknesses that make it more vulnerable to earthquakes.

It is important to minimize earthquake risk both by structural measures and non-structural measures. Structural measures entail retrofitting, that is modifying existing structures to handle seismic activity, and also ensuring new constructions are designed to with stand earthquakes in compliance with the building code.

Non-structural measures include reducing the risk of falling hazards inside the home, and developing a family preparedness plan.

Common examples of structural issues that can increase a building’s vulnerability to disaster include structures not securely anchored to their foundation or having weak studs and joists, unbraced pier-and-post foundations, or unreinforced masonry walls. Windows that are too wide, and roofs that are heavier than necessary also weaken the ability of a structure to withstand seismic shockwaves. Irregular-shaped structures that lack symmetry can also be at more risk of collapse.

Using lightweight materials that can bend without breaking can help make buildings more shock absorbent.

If you’re building a new structure, always use qualified architects, builders and engineers to design the structure. For an existing building, you can ask the same people to inspect your building and recommend upgrades, which are always far cheaper than having to repair or replace a seriously damaged structure after a powerful quake.

You can also assess the safety and structural integrity of an existing building and undertake modifications as required to improve its ability to withstand disasters. You always have an option of extending the retrofitting over a period of time. You don’t have to do it all at once; the important point is to get retrofitting done, if needed, before a quake occurs.

Some geological considerations

If considering a new structure for a home or business, give thought to the site’s location and the geology and geography of the area.

With the support of international nongovernmental agencies and technical bodies such as the Myanmar Engineering Society, Myanmar Geosciences Society and Myanmar Earthquake Committee, a number of seismic and earthquake risk maps have been developed which identify the location of quake fault lines and the types of soils in different areas. These maps – available through the national and region/state government – can be used to help identify safer locations for new constructions.

If you can avoid it, never build directly over, or too close to,a quake fault line, where quakes will be most intense. Ground shock waves cause 99 percent of earthquake damage to structures. Areas near large, active faults will be shaken more severely than areas even a slight distance away.

Solid rock near the surface that is well removed from a geological fault line offers the best building site for quake protection. Deep and unbroken rock, referred to as bedrock, generally will minimize earthquake damage whereas deep, soft, sedimentary soils will result in a more seismic force and displacement, causing the ground to move.

Landslides

In a mountainous country such as Myanmar, earthquakes can often trigger landslides, ripping apart homes on a slope or crushing homes downhill beneath displaced earth, falling rocks, trees, and other debris that could be loosened by earthquakes. Sites where landslides are most likely to occur should be avoided.

Lateral spreading of soil

Intense shaking during an earthquake can cause soil to separate into large blocks that move apart from each other, causing damage to the foundation of a house.During earthquakes, loose, wet sandy soil can become almost like quicksand and lose its ability to support structures, causing the foundation of a house to sink, break or tilt. Some soils offer greater “liquefaction,” or slide,than other types, and can cause more shaking and stress during quakes, which will result in loss of vertical support for the house or building.

The foundation of a home or business is literally the link between the structure and the ground. A well-built foundation is the first line of defense against damage to a structure.

Building codes are important

The Myanmar National Building Code, enacted in 2012, is now in the process of being rewritten to upgrade safety standards and to cover high-rise building construction. The new code will soon be submitted to Parliament for approval, but many architects and builders have already begun to implement some of its recommendations. When the code is approved,architects and building contractors across the country will have to conform to the new standards, offering more protection in quake-prone areas.

With this in mind, learn what the new building code contains to help you decide if you should perform retrofitting on a structure.

In collaboration with national technical partners, UN-Habitat has undertaken earthquake risk assessments for Sagaing city in Sagaing Region and Bago city and Taungoo city in Bago Region, drafting maps showing the most at-risk areas. The survey and maps have been provided to the respective regional governments.A seismic hazard assessment for Yangon city and an earthquake risk assessment have also recently been completed. As more such maps are created, local governments in the most earthquake-prone areas can consider the risks and needs when developing urban plans, creating industrial zones and building power projects.

U Myo Thant, a lecturer at Yangon University and secretary of the hazards section of the Myanmar Earthquake Committee, says the ongoing project would identify seismic sources, estimate source parameters and calculate seismic hazards to affected areas.

“The result will be maps showing active faults, engineering considerations, liquefaction [of soil] potential and earthquake potential,” he said. Knowing about earthquake faults and building stronger buildings goes a long way to reducing damage, injury and loss of life.

Make your home or business as safe as possible

If you are not able to make large-scale structural modifications to your home, there are still a number of things you can do to help reduce the risk posed by earthquakes. Firstly, it is important to identify the safe locations in each room or your home or business to protect yourself and others. Experts say around 30 to 50 percent of earthquake-related injuries are caused by falling objects or by furniture and other heavy items toppling over or sliding into people.

Any unsecured objects that can move, break, or fall as an earthquake shakes your home are potential safety hazards. Put all heavy items on lower shelves or on the ground.

Walk through each room and make note of such items, paying particular attention to tall, heavy, or expensive objects such as bookcases, home electronics, appliances (including water heaters), and items hanging from walls or ceilings.

Secure the items with flexible fasteners, such as nylon straps or with fixed hooks, to walls, lower shelves, or to cabinets with latches.

Other tips to arrange and secure furniture in your home to reduce the chance of injury:

– Fix items to sturdy walls or to the ground (Securing furniture such as cupboards to nearby walls top revent furniture such as tables and chair legs from sliding)
– Use stabilizing devices such as chains for fixing hanging lightings or other hanging materials to the ceiling to reduce falling hazards
– Install or use anti-shatter glass film on windows.
– Use metal straps to fasten your water heater or air conditioner to a stud in a wall.

Think about fire safety

Fire is a secondary hazard which may occur during or immediately after an earthquake as a result of ruptures in gas and electricity supply lines.  To help minimize the risk of fires in your home, remove all flammable liquids, such as painting and cleaning products, to an outside storage area. Don’t store flammable items near heat sources and appliances, particularly a water heater or furnace.

Secure gas lines by installing flexible connectors to appliances.

For earthquake preparedness, you must consider the big picture: geology, geography, how a structure is built, how you have arranged the furniture and other items in terms of safety, and – finally – how you respond upon the first signs of an earthquake.

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