Earthquakes: a scientific perspective

What is an earthquake? 

When two chunks of the ground abruptly slide past one another, an earthquake results. The fault or fault plane is the area where they slide. The epicentre is the point on the earth's surface that is directly above the hypocenter, which is where the earthquake begins under the surface.

Foreshocks can occur during an earthquake. These are lesser earthquakes that take place in the same location as the one that follows the major one. Before the greater earthquake occurs, scientists are unable to determine whether an earthquake is a foreshock. The mainshock is the term used to describe the greatest earthquake. Aftershocks that follow mainshocks are a given. These subsequent, weaker earthquakes take place in the same location as the primary shock.

What causes earthquakes and where do they happen?

The inner core, outer core, mantle, and crust are the four main layers of the earth. Our planet's surface is covered by a thin layer of skin made up of the crust and the top of the mantle.

However, this skin does not cover the entire surface of the globe in one piece; rather, it is composed of numerous pieces, much like a puzzle. In addition, these jigsaw pieces are continuously moving slowly in all directions, slipping past one another and colliding. These tectonic plates are the parts of the puzzle that make up the earth, and their limits are known as plate margins. The majority of earthquakes in the world happen on the numerous faults that make up the plate borders. Because the plates' edges are jagged.

Why does the earth shake when there is an earthquake?

The energy that would typically force the blocks to move past one another is being saved up while the fault edges are glued together and the rest of the block is moving. All that accumulated energy is released when the force of the sliding blocks ultimately displaces the resistance of the sharp edges of the fault and causes it to unstick. Like ripples on a pond, seismic waves made of the energy travel in all directions from the fault. When seismic waves reach the earth's surface, they begin to shake the ground and everything on it, including our homes and us, as they travel through the earth.

How are earthquakes recorded?

Seismographs are devices that record earthquakes. Seismogram is the name of the recording they produce. The seismograph features a base that is securely attached to the ground and a free-hanging heavy weight. The seismograph's base trembles whenever there is an earthquake, but the hanging weight does not. Instead, the spring or string on which it is suspended absorbs all motion. What is recorded is the change in position between the shaking portion of the seismograph and the still portion.

How do scientists measure the size of earthquakes?

The size of an earthquake depends on the size of the fault and the amount of slip on the fault, but that’s not something scientists can simply measure with a measuring tape since faults are many kilometers deep beneath the earth’s surface. So how do they measure an earthquake? They use the seismogram recordings made on the seismographs at the surface of the earth to determine how large the earthquake was (figure 5). A short wiggly line that doesn’t wiggle very much means a small earthquake, and a long wiggly line that wiggles a lot means a large earthquake. The length of the wiggle depends on the size of the fault, and the size of the wiggle depends on the amount of slip.

The size of the earthquake is called its magnitude. There is one magnitude for each earthquake. Scientists also talk about the intensity of shaking from an earthquake, and this varies depending on where you are during the earthquake.

Can scientists predict earthquakes?

No, and it is unlikely they will ever be able to predict them. Scientists have tried many different ways of predicting earthquakes, but none have been successful. On any particular fault, scientists know there will be another earthquake sometime in the future, but they have no way of telling when it will happen.

Is there such a thing as earthquake weather? Can some animals or people tell when an earthquake is about to hit?

Is there such a thing as earthquake weather? Can some animals or people tell when an earthquake is about to hit?

These are two questions that do not yet have definite answers. If weather does affect earthquake occurrence, or if some animals or people can tell when an earthquake is coming, we do not yet understand how it works.