Regional distribution
Some parts of our planet are more often and more severely afflicted by natural hazards than others. This is due firstly to the geological structure of the Earth and secondly to the extension of the climate zones.
Earthquakes mostly occur in the areas where ocean floors and continents move against each other and collide. The long arc of islands that make up Japan and the long stretch of the Andes located inside the coast of Chile are such collision zones and therefore more often afflicted by earthquakes than Finland, Brazil, or Canada.
Volcanoes and meteorite impacts are along with pandemics the greatest threat among the natural hazards. While meteorites fall everywhere on land and in the sea, the active land volcanoes of the world occupy only 0.6% of the total land area. Most land volcanoes are spread along the coast in areas that are also earthquake zones, while the myriad submarine volcanoes are located far from land. Mid-ocean volcanic ridges are formed where the ocean floors split and move apart. Hawaii and some other volcanic archipelagos have followed a different pattern, forming from magma expelled from individual hotspots in the mantle. The inner parts of the continents have few volcanoes, almost all the land volcanoes are located less than 100 km from the coast.
Tornados are also unevenly spread. The United States is struck by about 800 big tornados every year, but France, Belgium and the Netherlands are almost never struck, and never as severely. Large cyclonic storm systems known as typhoons form in the Pacific Ocean and move in over east Asia. In the Atlantic Ocean these storm systems are called hurricanes and move in over the southeast United States, Central America and the West Indies. The ships of the East India Companies experienced a third cyclone area in the Indian Ocean about the latitudes of Mauritius.
The warm and cold ocean currents and the cold air masses of the polar regions give rise to several climate and weather phenomena that may be counted as natural upheavals.
Flooding occurs in many places on the Earth and for many reasons. The most severe type of flooding happens when the ocean inundates. The place most affected by this phenomenon is Bangladesh. The country is just a few meters above sea level, is densely populated and one of the poorest countries in the world, so the price is paid in human lives when the tropical cyclones push water from the Bay of Bengal inland. This flooding is sometimes worsened when severe precipitation in the Himalayas causes the Ganges and Brahmaputra rivers to swell beyond their boundaries. Several places in Bangladesh also have ten times the annual precipitation that is common in Europe.
China is another country often affected by floods. Here, inundations are caused by typhoons from the Pacific. Severe flooding is also caused by the great rivers, which have changed their courses several times in historic time.