Earthquakes

The Earth Shakes

How Earthquakes Happen: Tectonic Plates

The Earth is made up of multiple tectonic plates. When these tectonic plates slip on each other, "there is an earthquake that releases energy in waves that travel through the earth's crust and cause the shaking that we feel" (usgs.gov). These earthquakes are called naturally occurring earthquakes. Earthquakes can also be caused by meteor strikes or volcanic eruptions, like in the infamous "Ring of Fire" in the Pacific Ocean. These eruptions and meteors are so strong that the sheer force can trigger earthquakes. It is estimated that 80% of the world's earthquakes occur in the Ring of Fire (environment.nationalgeographic.com).

The Dangers of Earthquakes

When these plates slip, "they send out massive vibrations called seismic waves", and the Earth shakes (environment.nationalgeographic.com). These seismic waves can be measured using the Richter scale, that explains the magnitude of an earthquake using a logarithmic function. The "Moment Magnitude Scale" is also used for it's wide applications on earthquakes of all sizes and locations. Whereas the magnitude or intensity of an earthquake varies as seen by these scales, all can be very dangerous and harm many people and cities. There are around 10,000 deaths caused by a magnitude 8 earthquake every year. These deaths are commonly induced by falling buildings, but can also be caused by mudslides, fires, floods, and tsunamis triggered by the earthquakes (environment.nationalgeographic.com).

Earthquakes on a Global Scale

Earthquakes can occur around the world on the edges of the Earth's 20 tectonic plates, called "fault lines". Its effects can be felt throughout near these sights, as well as around a region, however, depending on the size and magnitude of the earthquake. In 1556 an earthquake was recorded in China that killed 830,000 people. So as we can see, earthquakes are such a strong force that cities can see the effects in a broad area around the epicenter of a quake.

Famous Earthquakes

The Great Lisbon Quake of 1755:

The quake, said originate in the Atlantic Ocean, killed over 60,000 people.A massive series of tsunamis were triggered, drowning thousands in Lisbon. The tsunamis reached even the West Indies, 4,000 miles from Lisbon (earthquake facts.net).

The Ecuador Earthquake of 1906:

Killing 500 to 1,500 people, this quake stretched from Central Asia to San Fransisco. Waters were said to have risen 3.6 meters in 30 minutes, and waves were 30 meters high. With a magnitude of 8.2-8.8, quake effects were seen in a matter of hours (uses.gov).

Preparing for Earthquakes