Earthquakes

The world appears strangely still from above, but every mountain range and crevasse on its face is a scar, with many telling a story of when the earth roared to life. Earthquakes happen all around the world. Although earthquakes have been recorded on all seven continents, the majority of them occur in just three areas: the mid-atlantic ridge, an underwater line that runs down the Atlantic Ocean, the alpide belt, which stretches from the Mediterranean to Southeast Asia, and the circum-pacific belt, which traces along the Pacific Ocean's edges and is where approximately 80% of all earthquakes occur. Because of what lurks beneath the surface, these locations are prone to earthquakes.

Earthquakes are triggered by pressure, specifically pressure from severe stress in the Earth's crust. That tension can be created by volcanic activity or even man-made activities in some regions, but the majority of earthquake-inducing stress is caused by tectonic plate movement. Tectonic plates are continually moving either against, along, or beneath one another, but their edges can snag and stick the plates, causing them to move or attempt to move. The energy from this attempted movement fields around the edges, causing great pressure until the edges are forced to release and the plates slip. This results in a quick and tremendous release of energy, powerful enough to shatter the Earth's crust. This fracturing sends shockwaves through the ground, resulting in strong vibrations or quakes. Indeed, the world's most earthquake-prone areas are those where the most geologically active plates collide.

Seismographs record earthquakes and other seismic events. Seismographs oscillate when the ground shakes, generating a jagged line to reflect the movement. The higher the jagged line, the more powerful the earthquake. These recorded vibrations are then used to calculate the magnitude or strength of the earthquake. While there are various magnitude scales, seismologists favor the moment magnitude scale since it has no upper limit and measures earthquakes logarithmically. This indicates that each magnitude on its scale is ten times larger than the previous one. The moment magnitude scale, as opposed to the now-rarely used Richter scale, can be applied globally and can quantify earthquakes of the greatest magnitude. The greatest recorded earthquake happened in 1960, in Bolivia Chile, along the circum-pacific belt. The Valdivia earthquake was the most powerful of a series of quakes that devastated the region, measuring around 9.5 on the Richter scale.

The earthquake not only caused severe shocks on land, but it also generated a fatal tsunami up to 80 feet high. The tsunami raced across the Pacific Ocean, affecting countries as far away as the Philippines and Japan. Seismograph data revealed that the shock waves released by the Valdivia earthquake continued to jolt the entire planet for days. Some earthquake-prone locations have developed a variety of strategies to protect their communities. Buildings and bridges are intended to sway rather than collapse. When an earthquake happens, the public is trained on how to protect themselves and government officials conduct exercises to assure the safety of their citizens. Earthquakes can cause enormous devastation, yet the same forces have also sculpted exquisite features, each of which adds character to a planet so unique.