“Japanese people believed that a giant catfish caused earthquakes”“Undersea tremors send shockwaves through the water, undetectable at sea, which rise into giant waves when they reach the coast”Post-tsunami AcehIn the aftermath of the recent Italian earthquake, George Merrin looks at what makes them tick.ONE of the most deadly natural disasters that ever occurred was the 1556 Shaanxi Earthquake. 830,000 people died.There has always been superstition about earthquakes as a way for humans to explain these seemingly unexplainable and unpreventable events. They are as random as the frequencies at which the earthquakes occur. The Norse explained earthquakes as violent outbursts by Loki. The Greeks believed that earthquakes were caused when an angry Poseidon smashed his trident against the ground. Japanese people believed that a giant catfish, Namazu, caused earthquakes by thrashing about in the mud, trying to escape imprisonment.We now know that earthquakes are due to movements of tectonic plates beneath our feet. But even today as modern geology expands, seismologists still can’t predict with complete accuracy when an earthquake will occur.Earthquakes are largely measured on the Richter scale. The Richter scale is a logarithmic scale, which means that an earthquake that measures 2 on the Richter scale is ten times stronger than a Level 1 and so on. The largest recorded earthquake occurred in Chile in 1960 and it measured a whopping 9.5 on the Richter scale. This triggered Pacific wide tsunamis.Tsunami comes from the Japanese word for harbour wave. Undersea tremors send shockwaves through the water, undetectable at sea, which rise into giant waves when they reach the coast. Japan, on average, experiences 1500 earthquake each year. The difference with the 2011 one was that it triggered a tsunami.Whenever a major natural disaster occurs, all of the nuclear reactors automatically shut down. However, one of the reactors at the Fukushima Power plant failed to correctly shut down, causing high levels of radiations to be emitted into the surrounding area. Traces of Radioactive Iodine was found in cities such as Tokyo, Gunma, Tochigi, Niigata, etc. The clean-up of the tsunami caused an estimated $235 billion. It is the most expensive natural disaster in history.Recent reports indicate that global warming is going to cause more tectonic activity, leading to more volcanic and seismic activity. In his new book, Waking the Giant: How a changing climate triggers earthquakes, tsunamis, and volcanoes, Bill McGuire discusses how human induced climate change causes ice sheets to melt, reducing strain on tectonic plates and leading to an increase in these natural disasters. Theoretically, if more seismic activity occurs, more countries could be affected such as Greenland. If an earthquake was to occur there, it would cause glaciers to fall into the ocean and cause massive tsunamis.Human activity also can lead to earthquakes. Fracking is believed to cause earthquakes but this is disputed. As humans explore more than ever we need to take a step back and see what effects our activity can have on the world around us.