Hazard Mitigation: Planning for Tomorrow’s Disasters Today

by Ken Micallef
- Dec 21 2015 - 5 min read
On June 10, 2015, a woman walks through the ruins of a street in Bhaktapur, Kathmandu Valley, Nepal, after a magnitude-7.8 earthquake struck on April 25.

Earthquakes. Tsunamis. Floods. From climate change to the naturally occurring tectonic shifts of Earth’s evolution, natural disasters can strike anyone, anywhere. But in developing nations, the impact can be even more devastating without hazard mitigation.

Nonprofit GeoHazards International (GHI) embraces its goal to “help the world’s most vulnerable communities address hazards such as earthquakes, tsunamis, landslides, and climate change. Our solutions emphasize preparedness, mitigation, and building local capacity to manage risk. GHI has been pursuing this vital mission since 1991 while remaining independent of political, business, or research pressures.”

GHI Chief Operating Officer/Project Manager Janise E. Rodgers has worked in Nepal, Bhutan, and Pakistan, bringing her knowledge of how to reduce risk to local agencies combating Earth’s changes on a daily basis.

“The first questions we ask are, ‘What preventative measures are they already taking?’” Rodgers says. “‘What are their processes and policies?’ Then we know what we can build on. We need to know what the hazard is and what might be at risk first.”

A landslide that was triggered by heavy rain in Aizawl, northeast India, endangers vulnerable hillside buildings. This mountain city faces frequent rainfall-induced landslides as well as the threat of a major earthquake. GHI worked with local professionals to develop a landslide action plan and prioritized efforts to reduce earthquake risk. Courtesy Janise E. Rodgers.

Rodgers and her colleagues offer ways at-risk communities can minimize the effects of earthquakes, landslides, cyclones, and tsunamis. Rodgers describes several methods below.

Understand the Problem

“In some areas, you are dealing with multiple hazards,” Rodgers says. “It’s necessary to collect information to understand threats posed by each hazard. For example, for landslides—which can be a more frequent threat than earthquakes in seismically active mountain areas like the Himalayas—we need geospatial information because location determines whether people will be impacted and what the consequences might be.

“Tsunamis pose a different set of problems; people need to evacuate the inundation zone, so the focus is on how they can do that,” she continues. “Sea-level rise can increase vulnerability to tsunamis and other coastal hazards like storm surges; for example, a smaller tsunami or surge would inundate a larger area. But for all hazards, we always ask questions to understand the underlying things, like how people are addressing risk and what is at risk.”

Impact of a rainfall-induced landslide in Aizawl, India. Courtesy Lalrinpuii Tlau.

Make an Action Plan

“In the late 1990s in Katmandu [which experienced a magnitude-7.8 earthquake in April 2015], we assembled a broad spectrum of officials and technical specialists that understood earthquake risk—every area from seismology and geology to planning, engineering policy, and emergency response,” Rodgers says. “What would happen if we had a repeat of the massive 1934 event [which heavily damaged Kathmandu]? What would we need to do? Let’s say we have 20 years to work before it happens, what would we do to reduce the risk in that time frame?

“They had to set some priorities to work on schools, the ability to build things well, and raise general awareness,” she continues. “The action plan gave people a direction. When the risks seem overwhelming, bringing people together to build consensus on which things to do first can be very helpful.”

Build New Buildings Correctly

“With new construction, it’s not that much more expensive, perhaps 5 to 10 percent of total costs to include earthquake resistance,” Rodgers says. “In some cases, it doesn’t cost any more to make a building earthquake resistant; builders simply need to put the steel or concrete in the right place in the building. Some people think you need a thick floor slab in the building to make it safe. But if they put the extra money into the columns rather than the slab, they will have a much better, more earthquake-resistant building, and they might actually spend less money.

“A survey in Nepal found that people will spend more money to make their children’s school safe in earthquakes but not so much on their own house,” she continues. “People make economic trade-offs. But if you build it right in the beginning, then you don’t have to worry about going back and fixing it.”

Masons in Chocos, Peru, strengthened their Andean village’s school to resist earthquakes while learning techniques they can use on additional buildings. With GHI’s training, they learned to make stronger adobe blocks, add a geo-mesh membrane to hold walls in place during an earthquake, and properly connect the walls and roof together. Courtesy David Hermoza.

Retrofit When Necessary

Some risky older buildings can be fixed, or retrofitted, to better resist earthquakes. “We strengthened a masonry school in India by applying a ‘seismic belt’ made of wire mesh all the way around the building at the lintel, the top of the door,” Rodgers says. “It ties the building together. This method is codified in the Indian standard for retrofitting unreinforced brick buildings. We asked the person who developed it to join our team.

“During the same project, our team retrofitted an emergency call center using a reinforced concrete shear wall,” she continues. “The building, like many in India, had a concrete frame with infill walls made out of brick. The concrete frame had a minimal level of earthquake design. It’s nonductile, meaning the concrete frame would fail suddenly. We put shear-wall ‘bookends’ at the opposite ends of the building along the outside and tied them into the frame. This created strong, stiff elements that would keep the building from moving too far and would prevent the columns from failing.”

Get Compliance

“Most of the places we work have local codes that keep people safe if they are followed,” Rodgers says. “The hard part is getting compliance. Here in the U.S., the mechanism to get compliance is enforcement by a regulatory agency. Oftentimes, this mechanism isn’t in place where we work. In many places in India, the building codes aren’t mandatory, so you don’t have to follow them. This is because building bylaws are local, and cities can choose to make the national code mandatory or advisory. Ultimately, it’s whether they view the code as something that keeps people safe.”

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