The United Nations University calculates the World Risk Index using four factors: exposure, susceptibility, coping capacities, and adaptive capacities.
Exposure is the amount of natural hazards an area is exposed to.
The shaking of the earth can lead to a powerful wave in the ocean, which grows very large as it approaches the shore.
As if the earthquake itself was not bad enough, a tsunami can lead to major flooding in the same area. We've all been caught outside in a sudden rain storm, when the rain gets heavy and the wind starts blowing. But storms can also grow very large or very powerful or both, and when they do, they become natural disasters.
The other three factors are all exacerbated by poverty.
Millions of people are affected by natural disasters every year, and their impact can be calamitous.California is one of the planet's earthquake hot spots and gets more than 10,000 quakes a year.Most of them are so small that they are only felt by sensitive measuring instruments. Earthquakes can lead to another type of natural disaster, a huge flood known as a tsunami.In the past 20 years, 90 percent of major disasters have been caused by 6,457 recorded floods, storms, heat waves, droughts and other weather events.Indonesia, India and the Philippines are among the five countries hit by the highest number of disasters, besides the United States and China.In a short essay on this natural disaster, the author wrote that "the totality of destruction" from the San Francisco earthquake "was extraordinary." This type of natural disaster happens when underground stresses cause two sections of the earth to abruptly move past one another. A small earthquake can hardly be felt, but a large earthquake releases so much energy that buildings can tumble as entire cities shake.An earthquake can strike anywhere in the world, but some areas are much more active than others.According to a November 2015 report from the United Nations, the rate of weather-related disasters (such as cyclones, typhoons and droughts) is growing.Between 20, the annual average of weather-related disasters was 335, an increase of 14 percent from 1995 to 2004 and almost twice the average recorded from 1985 to 1995.If you've seen "The Wizard of Oz," then you know about tornadoes.These fearsome twisters don't cover huge areas like a hurricane, but their winds can be even more powerful.