Natural Disasters:
What are they and how can we prepare for them
In Singapore, we are very fortunate to be shielded from the major natural disasters that occur in other countries around the world. While Singapore may experience floods and thunderstorms, we remain well protected - because of our geographical location and characteristics as an island - from the destructive weather conditions that threaten the safety and lives of others elsewhere.
What, then, are natural disasters? Natural disasters are naturally occurring phenomena such as floods, volcanic eruptions, hurricanes, earthquakes and tsunamis; these are caused by climatic and geological occurrences that are beyond our control, cannot be avoided, and almost impossible to prevent. According to the United Nations, natural disasters have caused the deaths of more than a million people, affected 1.8 billion people in terms of loss of health, homes and livelihoods, and cost $685 billion in economic and structural damage in the last decade alone. Indeed, natural disasters kill more people worldwide than wars.
Let us understand a little more about some of these natural disasters.
Did you know that earthquakes, tsunamis and volcanic eruptions are closely related? The outer crust of the earth is made up of 8 major and several minor plates; when a plate shifts, it moves against another, pushing the adjacent plate under it or crashing into that plate. Such actions produce energy that may be trapped for many years. When this energy is freed, it results in earthquakes, tsunamis and volcanic eruptions.
Indeed, natural disasters kill more people worldwide than wars.
In 2008, an earthquake in Szechuan, China, resulted in 69,195 deaths, 374, 177 injured and 18,392 people missing. As you can see, earthquakes can have devastating effects: buildings are reduced to rubble in a matter of seconds and people who are trapped in this rubble often die because of their injuries, blood loss or dehydration as it can take rescuers several days to locate them. While the modern search and rescue process has been made easier with the deployment of motion detectors, microphones and rescue dogs, it may not always be successful. The dead also, sadly, present health risks because their decaying bodies may pollute the surrounding environment, perhaps contaminating water sources.
The Tohoku Earthquake in Japan on 11 March 2011, measuring 9.0 magnitude on the Richter scale, not only caused the collapse of numerous buildings but resulted in a huge tsunami. This tsunami had 40-metre high waves that wreaked havoc on the coastal towns of Tohuku Prefecture, taking 16,000 lives. More significantly, that earthquake caused the meltdown of the Fukushima Daichi Nuclear Power Plant and radioactive pollution in the area, and far beyond in the Pacific Ocean, is still being detected today.
So what are tsunamis? Tsunamis typically consist of a series of waves like a “wave train”, and are caused by the removal of water from a large body of water such as an ocean or a large lake. Tsunami waves are much longer than ordinary ocean waves and resemble a rapidly rising tide, hence they are also referred to as “tidal waves”. Although the effect of tsunamis is limited to coastal areas, their destructive potential is mammoth: the 2004 Indian Ocean tsunami was among the worst natural disasters in human history, killing more than 230,000 people in 14 countries. Earthquakes, volcanic eruptions, landslides, glacier calvings, meteorite effects and other turbulences above or under water (including blasts from underwater nuclear devices) all have the potential to produce tsunamis.
Tsunamis typically consist of a series of waves like a “wave train”, and are caused by the removal of water from a large body of water such as an ocean or a large lake.
Like earthquakes, volcanic eruptions are also caused by plate movements. When a plate slides under another, it causes pressure to build in the mantle. The liquid magma has nowhere to escape except upwards, causing cracks in the earth’s crust. These cracks allow gases to escape along with ash, magma and large pieces of rock. In 1883, Krakatoa - a large volcanic island between Sumatra and Java - erupted over two days, raining superheated volcanic ash, lava and rocks onto the surrounding islands and killing thousands living along the coast. By itself, this eruption would not have been so devastating, but the tsunamis created by the rocks and magma falling into the sea killed close to 30,000 people living on coastal Java. The final explosion that ripped Krakatoa apart was heard as far away as Africa and Australia. The dust cloud thrown into the atmosphere caused world temperatures to drop for ten years. It was one of the most devastating volcanic eruptions in history.
Did you also know that typhoons, hurricanes and cyclones refer to the same weather condition? They describe the same phenomenon of large storm systems with circular or spiral movements - usually hundreds of kilometres in diameter - of forceful wind and heavy rain, caused by very low areas of air pressure that are present over large bodies of warm water. “Typhoons” refer only to the storms in the Western Pacific, “hurricanes” refer to similar storms in the Atlantic Ocean and Eastern Pacific, while in the Indian Ocean, such storms are called “tropical cyclones”. Whatever the name, these storms have wind speeds of at least 119 kilometres per hour (km/h) and can cause severe and massive damage. Hurricane Katrina in 2005 and Hurricane Sandy in 2013 brought devastation to the coastal areas of New Orleans and New Jersey in the USA. Closer to home, Cyclone Nargis in Myanmar and Typhoon Haiyan in the Philippines in 2013 caused significant loss of life and destruction. When the wind speeds hit 241 km/h, the storms are known as “super typhoons”. Typhoon Haiyan, which took place in the Philippines in November 2013, was a super typhoon.
Another example of natural disasters is avalanches. Heavy snowfall causes snow to pile thickly onto mountain slopes, and this buildup can have fatal consequences if there is a trigger that causes the snow to plunge suddenly downhill, gaining momentum and volume as it does so. On 18 April 2014, an avalanche on Mount Everest killed 16 Nepalese mountain guides, the deadliest tragedy ever on that mountain.
Like avalanches, landslides occur when huge volumes of rocks, mud or soil tumble down a slope, triggered by heavy rains, earthquakes or human activities like construction work nearby. The biggest landslide in history was triggered by the eruption of Mount St Helens in 1980, where almost 3km3 of rocks and debris hurtled down mountain slopes.
Like avalanches, landslides occur when huge volumes of rocks, mud or soil tumble down a slope, triggered by heavy rains, earthquakes or human activities like construction work nearby.
Floods are some of the most devastating natural disasters. They are caused by unusually high rainfall from storms that cause rivers or lakes to overflow. The Huang He (Yellow River) floods in 1887, 1931 and 1938 were caused by the overflowing of the Huang He, China’s second longest river. These three floods collectively killed millions and are still considered to be the three deadliest floods in history and among the most destructive natural disasters ever recorded.
While natural disasters cannot be prevented, the risk of loss of life and injury can be lessened with good environmental planning, evacuation plans, and design standards.
The best way to minimise the effects of natural disasters is to create early detection systems that allow advance warnings to be given to national and global communities. The focus should be placed on reducing the severity of the impact these disasters have on every aspect of people’s lives. These destructive effects can be successfully reduced by implementing effective monitoring and warning systems, building codes, flood defences, comprehensive disaster management plans and educating citizens on disaster preparedness.
For example, in earthquakeprone areas like Japan, disaster preparedness is taken very seriously. Japan has the world’s most sophisticated earthquake early-warning systems. Emergency drills organised by public and private organisations allow for people to practise how to transport “trapped” commuters from their offices to their homes. In 2000, Japan’s building codes were revised with specific requirements and mandatory checks. Disaster preparedness is a priority even at the local level: from 1979 to 2009, Shizuoka prefecture alone spent more than US$4 billion to improve the safety of schools, hospitals and social welfare facilities.
Another good example of disaster preparedness are the measures that have been taken to prevent rivers from flooding their banks. The Chinese have built dykes and embankments along rivers like the Huang He to prevent floods. Dredging a river to deepen its bed can also prevent floods. The most effective method has been to build dams and Hydro-electric Power plants to produce energy while controlling floods.
Yet, despite all the advances in modern technology, we are still not able to predict where and when natural disasters such as typhoons, floods and earthquakes are going to occur. But we do know that they will inevitably come, and what we can and must do is to be prepared.