# How to calculate the transmission ratio of pulleys

## How to calculate the epicenter

Science 2021

Because epicenter, it is the point on the earth's surface directly above the center of subterranean movement that is perceived as an earthquake. This movement gives off waves of various kinds

### Content:

The epicenter is the point on the earth's surface just above the center of underground movement, which is perceived as an earthquake. This movement emits various types of shock waves that move at different speeds. The different waves can be detected by sensitive instruments called seismographs.

From the time difference between the first recorded occurrence of different types of waves of the same earthquake, a scientist studying the seismograph record can determine the distance to the epicenter of the earthquake, but not determine the direction. However, with three or more seismographs, a scientist can triangulate a location.

Measure the difference in arrival times between the first shear wave (n) and the first pressure wave (p), which can be interpreted using the seismogram. Multiply the difference by 8.4 to estimate the distance from the seismograph station to the epicenter in kilometers.

Open the compass until the gap equals the calculated distance to the epicenter. On a world map, draw a circle centered on the location of the first station. The epicenter can be anywhere on this circle.

Repeat the calculation process for the distance from the second seismograph station and draw a circle of the calculated radius on the map centered on that station. This circle and the first cross at two points. The epicenter can be at any point.

Repeat the calculation and drawing process for the third seismograph station. The three circles meet at a common point, the epicenter.