How do scientists detect earthquakes

how do scientists detect earthquakes. explain.

An earthquake is caused by two slabs of the earth's crust, called tectonic plates, pushing past or against each other to where tension builds up between the plates. Finally, the tension overcomes the friction and the two plates slip. This then causes violent shaking as the plates slip along against each other.

This vibration can be felt all around the globe as it resonates through the earth's crust. So, we have placed monitoring stations, called seismographs, at specific points around the world. When the vibrations of the earthquake are felt, this causes a finely balanced needle to move a pen across a scrolling chart of paper that indicates the intensity (magnitude) of the vibrations and the exact time they were detected.

By triangulation, scientists can look at the time and intensity of when the vibrations were felt at a number of seismographs at different stations to determine that an earthquake must have occurred at a specific time and at a specific location (the epicenter) to get the recorded times and intensities at the different stations.

Ok, here is a case in point explanation :)

Push your palms together hard, pull one upward, and one downwards fairly hard. Before they slip, you will notice that they slip very small amounts, increasing up to the point where they slide past each other.

It is pretty much the same with earthquakes, they give off very small tremors before a major earthquake, and increase the closer an earthquake is. Scientists put probes deep into the ground near a fault, and measure these tiny vibrations, and when they measure a marked increase, report an earthquake warning.

It is far from an exact science, sadly. However they are getting better and better at predicting earthquakes.

Hi.

Seismographs are the established instrument but there are also other devices.

Electrostatic forces are generated when the crust comes under pressure. These charges can be detected using fairly low tech systems like the gold leaf electroscope

Also, sounds can be detected. Sensitive microphones are available.

Another low tech system uses lasers to ricochet off mirrors to scan vast areas. Any offset of the beam indicates movement.

All theses devices can be networked to give 3d positioning of the epicentre.

With machines that can detect very slight changes in the earth. It's called a Seismograph.

With seismic monitoring instruments (seismometers and accelerometers).