An earthquake is a tremor that affects the surface as a result of energy release underground from either tectonic plate movement or other external factors. Earthquakes come in different shapes and sizes, the magnitude of a quake is recorded using the Richter Scale. From small, barely felt tremors that register as a 2 on the scale, to larger more devastating earthquakes coming in at 7, which have the ability to level entire cities – the destructive power of a quake is undeniable.
Over time, some areas have become more prone to earthquakes or other forms of seismic activity; these areas encounter quakes of varying frequency and size throughout the year. One of the most well-known and documented areas of seismic activity is the Great Ring of Fire, which surrounds the entire Pacific tectonic plate, stretching from Japan, New Zealand and the Pacific Islands to California and South America.
As aforementioned, earthquakes are considered a natural disaster caused by the geological movements of plates, however there are some other causes, both human and natural. Volcanic activity, landslides, mine blasts and nuclear tests have all been linked to the formation of an earthquake. Compounding effects can lead to more dangerous earthquakes. Indeed, depending on the location, or epicentre of an earthquake, tremors can have different effects on the local environment.
Earthquakes generated below sea level are very likely to create a tsunami – like the one that hit the Indonesian coast in 2004, or the one that affected Japan in 2011 – whilst one in a mountainous area could lead to landslides or avalanches. Compounding effects can see a mixture of all of those, such as when a small magnitude-four quake hit the west coast of Greenland, triggering a massive landslide and tsunami which destroyed an entire village.
Of course, earthquakes can also have negative effects on areas that do not see any additional compounding effects. Highly populated areas or major cities are extremely vulnerable to earthquakes, but most tremor-prone areas tend to be somewhat prepared for any form of activity. From evacuation plans to earthquake-resistant infrastructure and buildings, people living in high-risk areas like California and Japan are well versed in how to deal with high-magnitude tremors.
It is estimated that there are around 500,000 earthquakes which occur each year, with only about 100,000 of which can be felt. Minor earthquakes occur nearly constantly around the world in places like California, New Zealand and India.