At the beginning of 2010, the world had to cope with two mega geo-disasters - the Haiti and Chile earthquakes. The earthquake that hit Haiti on January 12 was of 7.0 magnitude. Seismo-tectonically, Haiti is bounded by two strike-slip faults; from north to south, they are the Septrentional Fault and the Enriquillo Plantain Garden Fault. The mega geo event was due to the rupture along the Enriquillo Plantain Garden Fault after 240 years of continuous strain accumulation.

The damage and loss caused by the Haiti quake is beyond anyone’s imagination. Official data have revealed the death toll to be over 230,000 and injuries at beyond 300,000. There was widespread collapse of residential, life line, heritage and government buildings throughout the city of Port-au-Prince, the country’s capital. Around 20,000 commercial structures and 225,000 residences collapsed or suffered severe damage and will need to be demolished.

The Haitian government is in a shambles. Ministries and all important buildings have collapsed, and power, water and communications have been disrupted. In spite of international efforts, there is desperate shortage of water, food and medical care. The education system in Haiti has "totally collapsed"; half of the nation’s schools and the three main universities suffered severe damage. Much of the city became unrecognisable following the earthquake.

Poor construction

The main reason behind these widespread damages is the way the buildings were constructed. The poor construction is evident in the midst of the ruins and rubble: the brittle steel, coarse non-angular aggregate, weak cement mixed with dirty or salty sand and the widespread termination of steel reinforcement rods at the joints between columns and floors of buildings where earthquake stresses are highest.

Furthermore, the damages clearly indicate a complete absence of seismic detailing in Haitian construction. From informal housing to recent multi-storey buildings in downtown Port-au-Prince, only a handful seem to have been built with any awareness of the most basic principles of seismic design and construction. It appears there is no building code in Haiti, and there are no licensing requirements for architects, engineers or contractors. Overall damages have clearly shown the enormous lack of preparedness for an impending earthquake in Haiti.

Just after the Haiti earthquake, central Chile was struck by a devastating earthquake of 8.8 magnitude on the morning of February 27. The quake was because of the oblique subduction of the Nazca Plate beneath the South American plate where the strain is being accumulated at higher rate. The epicentre was located 325 kilometers southwest of its capital, Santiago, and the nearest city is Concepción. The Chilean government has revealed that about 1.5 million houses were damaged out of 4.5 million. The quake affected over two million people across the nation. However, there were only 512 casualties despite its bigger magnitude than the Haiti earthquake. The majority of the homes that collapsed were older buildings that were constructed with a mixture of sand, clay, straw and water.

Both the Haiti and Chile devastating earthquakes are unique in nature and scale of damage. The energy of the Chile earthquake was 512 times greater than that of the Haiti earthquake. Interestingly, despite the lower energy compared to that of the Chile earthquake, there were more fatalities in Haiti. The reason for this discrepancy between Haiti and Chile earthquakes in casualty figures is the readiness of the cities and their people to cope with the approaching disaster.

As Chile is known as a country of very high seismicity and has also experienced the largest earthquake ever recorded on earth, in 1960, the Chileans are well aware of the possibility of large earthquakes in their country; therefore, measures for mitigating their risks were taken. The Chilean seismic design provisions for buildings and infrastructure are quite advanced and sometimes as stringent as those adopted in California. On Haiti’s side, many of the residential buildings in Haiti are non-engineered and constructed using materials such as bamboo, mud and mud bricks. Even the modern multi-storey buildings in the capital city were built without seismic detailing. These buildings virtually have weak resistance to the earthquake forces and so collapsed.

It is, therefore, the Chilean government’s capability to strictly enforce the seismic design codes in the country that made a difference in such a major earthquake. A good lesson learned from the aftermath of the Haiti and the Chile earthquakes is that disaster preparedness is a key to preventing possible disastrous events or at least minimising their impacts on the society.

In the context of the Himalayan region, the situation will be much more alarming than Haiti and Chile. Most of the south Asian mega cities are located in the frontal part of the active Himalayan belt, where a number of fault lines bound the major cities. The Kathmandu Valley, where the capital city of Kathmandu and two other cultural cities Patan and Bhaktapur are located, is widely known as a hot spot for an impending Himalayan mega earthquake because of its central location in the seismically active Himalayan belt. It has already experienced several catastrophic earthquakes (in 1934 and 1988), but the readiness of the people and capacity of the government has not improved. The economic activities, health and education facilities, employment opportunity and security assurance have made Kathmandu Valley a lucrative dwelling place for three million people despite the discernible risk of an earthquake.

For these population, the cities are being rampantly planned and constructed in vulnerable areas by builders exclusively for their economic benefit without giving due consideration to open space, life lines, level of risk induced by newly built substandard structures and many other social factors.

The post disaster assessments in Haiti and Chile have clearly shown that preparedness is the only way to preventing or minimising the risk of disasters. In the case of an earthquake, it is even more atrocious because there is almost no warning time for the onset of an awaiting earthquake. Therefore, the government should come up with a comprehensive plan and policy to reduce the risk of an earthquake in the Kathmandu Valley taking due consideration of the following:

• First, our reactive approaches to handling natural disasters must be replaced by a more proactive attitude against earthquake risks.

• Periodic loss estimation exercises should be carried out based on detailed seismic hazard, vulnerability and risk assessment as decisions cannot be taken only by applying general understanding on earthquakes at a regional or national level to a city.

• The public must know and the engineer should practice building codes in the design and construction processes. It is the duty of the local government authorities to build the special capacity of the technical staff for proper enforcing and monitoring processes.

• Seismic retrofitting of existing buildings has to begin immediately. No doubt it is a long-haul process, but time is running out and no significant effort has been undertaken in Kathmandu yet.

• Given the uncertainties with earthquakes in terms of magnitude and intensity, complete risk mitigation is not a practical solution.

Earthquake scientists have repeatedly been warning the people of the Himalayan region that the mega event is long overdue in the central part where megacities of South Asia are located. The devastation from an overdue event around Kathmandu could be more widespread than that of Haiti because its population is almost double than the Haitian capital and we share similar building structure, landform, economy, level of preparedness and capacity to cope with disasters.

There are only two mountain highways (Prithivi and Araniko) that can be used for evacuation, and relief and rescue may be blocked due to earthquake-induced landslides creating turmoil in the valley.

New policies

There is no comprehensive planning and preparedness to cope with the awaiting earthquake from both the government and NGO sides. Our previous experiences in Nepal show that the existing disaster management plans will concentrate only on clearing the debris and corpses during the post seismic periods. Even for these, the Disaster Management Section has no equipment.

It is also essential that new policies are formulated and based on the lessons learnt from various past earthquakes. The Chile and Haiti earthquakes have clearly taught us an important lesson that preparedness is the only way for developing nations to minimise the risk of an earthquake.

Dr. Deepak Chamlagain
(The author is a Geological Disaster Specialist at New Delhi-based SAARC Disaster Management Centre and can be reached at dchamlagain@hotmail.com)

Source: Chamlagain, D. (2010),"Lessons From Haiti And Chile Earthquakes",Rising Nepal