What are earthquakes?

On February 6th, Turkey and Syria experienced one of the worst humanitarian disasters in history. A 7.8 magnitude earthquake claimed more than 45,000 lives and this number is still increasing. Unfortunately, this is not the first time this type of natural disaster has occurred. In 1985 an 8.0 magnitude earthquake caused destruction in Mexico City claiming more than 5,000 lives. In 1906 San Francisco was affected by a 7.9 magnitude earthquake taking more than 700 lives. To understand why these events are so deadly is important to first understand what an earthquake is. 

To comprehend the quake, we need to become more familiar with the Earth. The Earth is formed by four layers, think of it as an onion. We have the inner core (a solid), an outer core (which is liquid), the mantle that is a semi-solid fluid, and the solid crust. The crust, also known as the lithosphere, is made up of different pieces. Imagine a desert where the soil is so dry that it starts to crack and separate, that is how the lithosphere looks. The different pieces of the lithosphere are called tectonic plates and they are constantly moving as they float on the fluidic surface of the mantle. The movements sometimes result in slips of the plates, when one plate slides under another, thus causing the earth to shake. Not all earthquakes are the same and they can be measured using special tools.

To measure an earthquake we use a seismometer, which records the vibrations that travel through Earth. A seismometer can also help us record the time, location, and magnitude of earthquakes. The magnitudes, like the values of 7.8 and 8.0 from the introduction, fall on a number scale called the Moment Magnitude scale, and can be used to compare the strength of the earthquake. An earthquake becomes stronger the higher its magnitude gets. You probably have heard of the Richter scale, however, it might surprise you to learn that it is not used anymore. It was originally created to measure earthquakes in California and it is not suitable for other parts of the world. 

The strength of an earthquake doesn’t cause massive loss of life alone. After effects caused by the seismic activity, such as collapsing buildings, falling bridges, and explosions contribute to the destruction. We can’t prevent naturally occurring earthquakes but we can stay informed with our local authorities about the hazards. Together, we can learn about earthquake safety, and stay up to date on building structural upgrades. 

By Karen & Mark