World's biggest quake-risk cities named

20:01, Aug 13 2012

GeoHazards International is a non-profit organisation dedicated to providing assistance in the form of education to governments to prepare for the consequences of earthquakes in or near populated areas.

They have compiled a list of the highest-risk cities. The risk- assessment calculation is based on a variety of factors such as: the level of seismic activity associated with the region, the potential for landslides and floods, the existence, application and enforcement of appropriate building codes, the adequacy of the rescue and fire-fighting services and the abilities of the life-saving medical facilities. Based on the assessment of these factors, the three cities most susceptible to big earthquakes and least capable of dealing with the consequences are as follows.

3. Delhi, India

The Indian subcontinent has a history of devastating earthquakes arising from the relentless movement (47 millimetres a year) of the Indian tectonic plate into Asia.

A recent study by the World Bank and United Nations divided India into earthquake-risk zones, with Delhi deemed to be sitting in a high-risk zone.

The degree of seismic activity coupled with its enormous population density (a city of 12.5 million), frail buildings, poor- rescue facilities and the post- quake flood threat presented by the nearby Yamuna River, put Delhi at No 3 in the list.


2. Istanbul, Turkey

Turkey is criss-crossed by faults produced by the African plate pressing into the Anatolian block and has a long history of earthquakes. The most destructive recent quake was the Izmit quake of 1999 which killed 17,000 people. The significance of this earthquake is that Izmit, a city of 300,000, is 100 kilometres east of Istanbul, and there is compelling evidence that the quake zone is progressively moving towards Istanbul. The huge population (13 million), ancient buildings and poor preparedness of Istanbul make it the second-most vulnerable city to seismic hazards in the world.

1. Kathmandu, Nepal

The Himalayan mountain chain is the result of the Indian plate driving into Asia. Sitting at the foot of the Himalayas is the kingdom of Nepal and its capital Kathmandu. Although only 1.5 million people live in the Kathmandu Valley, the population density is one of the highest in the world. The earthquake risk is very high; the last really big earthquake to hit Kathmandu was in 1934 when 11,000 people were killed. The Kathmandu Valley can expect to be on the receiving end of a large earthquake about every 75 years. In 2011 the region was hit by a 6.9 earthquake, which was deep and centred some distance from the city. However, eight people were killed, and a British geologist, Professor Dave Petley, described it as a "wake-up call". Given this trend, it cannot be long before the next big earthquake strikes. The high-population density, the absence of building codes, the poor rescue, fire- fighting and medical facilities, make Kathmandu the most vulnerable city in the world to earthquake risk. As a result, the loss of life is likely to be in the several tens of thousands.

The first world has high risk cities as well; top of that list is Tokyo which sits close to the junction of the Pacific, Eurasian and Philippines tectonic plates. This city has a very complex tectonic landscape and the risk of a big earthquake is very high. The last big Tokyo quake was in 1923 which killed 100,000 people. Before the 2011 Japan quake, the risk of the big one hitting Tokyo was put at 30 per cent in the next 30 years, which in seismic risk terms is huge. However, geologists think that the 2011 quake centred offshore from Japan has increased this risk and experts are now busily revising their risk data upwards - figures as high as a 70 per cent probability within the next four years have been estimated by Tokyo University. A big quake in Tokyo would be traumatic; however, no city in the world is better prepared, so the actual risk to an individual life is lower than Kathmandu, Istanbul and Delhi.

Wellington doesn't figure in the study which was restricted to the Americas and Asia, but its risk is lower than the cities mentioned because Wellington's population density is relatively low, the preparedness is good and the seismic return rate is smaller (11 per cent in the next 100 years).

For Kathmandu, Istanbul and Delhi there is a clear and present danger of a serious earthquake with devastating consequences. The hope is that awareness of their governments increases.

Taranaki Daily News