A magnitude 7.0 earthquake struck the Caribbean island nation of Haiti on Tuesday, January 12, 2010, the most powerful earthquake to hit Haiti in almost 200 years. The epicenter was 15 miles southwest of the country’s capital, Port-au-Prince, at a depth of 6.2 miles below the ground surface. The event occurred on the Enriquillo-Plantain Garden fault system in southern Haiti which is an east-west trending left-lateral strike slip fault. This fault system has not generated a major earthquake in recent decades although it may be the likely source of historical large earthquakes in 1860, 1770, 1761, 1751, 1684, 1673, and 1618. The earthquake was felt throughout Haiti, the Dominican Republic, southeastern Cuba, eastern Jamaica, and in parts of Puerto Rico and the Bahamas. However, because the earthquake source was shallow, the intensity of shaking was stronger and more localized at the region along the fault.
There is no way of knowing the death toll or causalities (injuries and fatalities) after few days of such a catastrophic earthquake. However, the death toll could rise well above 100,000 according to Haiti’s prime minister speaking to the CNN. One third of the Haiti’s 9 million people could need emergency aid according to the International Federation of the Red Cross. Many hundred thousands are expected to be homeless and sleeping in the streets. If true, this would put Haiti earthquake as one of the deadliest quakes in the last four decades. The latest of such catastrophic quakes was the May 12, 2008 magnitude 7.9 Sichuan earthquake in China which is considered to be the third deadliest quake. According to the US Geological Survey on Sichuan earthquake; at least 69,195 people killed, 374,177 injured and 18,392 missing and presumed dead. More than 45.5 million people in 10 provinces and regions were affected. At least 15 million people were evacuated from their homes and more than 5 million were left homeless.
Haiti is the poorest country in the western hemisphere with more than 80% of its population lives below the poverty line. The earthquake caused severe damage and destruction in the Port-au-Prince area which is densely populated. Haiti’s President issued a desperate appeal for international aid following the earthquake stating that the tremor was catastrophic and is unimaginable, and that the Parliament, the tax office, schools, and hospitals have collapsed. Other collapsed or severely damaged buildings include the UN peacekeeping mission, the presidential palace, the national cathedral, and the main prison. Haiti most likely does not have a building code where substandard design, inadequate materials, and shoddy construction practices contributed to the collapse of buildings. Even newer construction has been developed to withstand the vertical loads of hurricanes but not the lateral loads of earthquakes. The load path, and the engineering design and connection detailing concepts for hurricanes and earthquakes are completely different. Many buildings collapsed just like pancakes as builders put the reinforced concrete roof on top of low-grade bricks, construction blocks, or thin columns. Other nonductile reinforced concrete buildings collapsed because builders or owners were trying to cut costs by skimping on cement, adding excessive water, and reducing the amount of reinforcing steel.
The situation would definitely be different if a similar earthquake hits the United States where structural engineers design buildings to resist earthquake lateral forces according to the current stringent building design codes. In the meantime, the local governments enforce good construction practices. However, there are still many lessons that can be learned from Haiti earthquake, the most important are:
Earthquake awareness should be in everyone’s mind. Haitians did not experience a large earthquake since 1860 and it seems they did not even know that they live on or close to a historically active fault system. In the United States, raising public earthquake awareness in the Central and Eastern United States shall be encouraged for many active seismic regions that experienced large historical earthquakes and has the potential to develop moderate-to-large future earthquakes. Those regions include, but not limited to:
- The New Madrid Seismic Zone in southeastern Missouri where three of the largest historical earthquakes of magnitude 7.0–8.0 occurred in the winter of 1811–1812; on December 16, 1811; on January 23, 1812; and on February 7, 1812. The region of potential impact due to earthquake activity in this zone is comprised of eight states: Alabama, Arkansas, Illinois, Indiana, Kentucky, Mississippi, Missouri, and Tennessee.
- The Wabash Valley Seismic Zone along Illinois – Indiana border which is capable of generating a magnitude 7.1 earthquake that has the potential to impact three states: Illinois, Indiana, and Kentucky.
- The Charleston Area in South Carolina that was hit on August 31, 1886 by one of the largest earthquakes in United States history.
Building performance in Haiti earthquake was very poor including unreinforced masonry and nonductile reinforced concrete buildings. Although those two types of construction are no longer allowed to be built in California, however, many of these buildings still exist and are not retrofitted. In addition, buildings constructed, remodeled, or retrofitted before the 1980’s in active seismic regions of the United States are more likely to suffer earthquake damage because they do not have adequate reinforcement in the concrete walls or masonry walls, or were not constructed according to modern building codes. Other issues may exist such as unbraced soft story, unbraced basement or crawl space, or inadequate foundations anchorage.
Earthquake preparedness seems absent in Haiti earthquake either from the government side which may only be concerned with hurricanes or from individuals who cannot afford even buying and maintaining emergency supplies because of the level of poverty. During the second annual Great California ShakeOut earthquake drill, Californians were reminded to prepare a personal survival kit for each family member and a household emergency kit, and to stockpile emergency food and water for 1-2 weeks to be prepared for the next inevitable earthquake. In fact, anyone who lives in an active seismic region in the United States and around the globe should have an earthquake preparedness plan.
How can Individuals Reduce Earthquake Risks?
If your home is constructed before the 1980’s, you probably need to retrofit it, especially if it is close to an active fault (15 miles or less). Seismic retrofitting measures ensure the structural integrity of your home to withstand earthquakes with little structural damage. Retrofitting is your own decision at your own risk according to your financial situation as it may be costly. However, it may be addressed one step at a time. The best return on the investment of retrofitting efforts is to initially address the foundations issues followed by bracing the cripple walls, then bracing the soft story, and ending with bracing or anchoring the masonry chimney.
You should mitigate the contents of your home whether you retrofit it or not. Earthquake mitigation measures are simple techniques taken to secure non-structural elements and contents of your home to the studs of the interior walls, in order to reduce the risk to lives and investments, using inexpensive hardware tools and materials found in hardware stores and home centers. Items in the garage should also be secured to reduce damage to vehicles. Self-mitigation techniques can be undertaken by homeowners as they are simple to explain and require no special expertise, materials or tools to implement.
Earthquake awareness and preparedness are key elements for anyone who lives in an earthquake country. The US Geological Survey website is a great source of earthquake-related information by Country/Region. Haiti earthquake serves as a reminder for people to review, update, or develop their own earthquake preparedness plan. Emergency food and water for 1-2 weeks shall be maintained at any time along with personal survival kits and a household emergency kit. The benefits of seismic retrofitting and mitigation go well beyond being simply reducing financial losses. It will make your home safer and help in returning your family much more quickly back to their normal life style.