Question

causes of earthquake ,measuring instrument ,seismograph working

Answer 1

Seismologists use two main devices to measure an earthquake: a seismograph and a seismoscope. The seismograph is an instrument that measures seismic waves caused by an earthquake. The seismograph has three main devices, the Richter Magnitude Scale, the Modified Mercalli Intensity Scale, and the Moment-Magnitude Scale.

Answer 2

Earthquakes are usually caused when rock underground suddenly breaks along a fault. This sudden release of energy causes the seismic waves that make the ground shake. When two blocks of rock or two plates are rubbing against each other, they stick a little. ... When the rocks break, the earthquake occurs

mesuring instrument= seismograph

What doesn't move, however, is a suspended mass inside the seismograph, called the seismometer. During an earthquake, the seismometer remains still while the case around it moves with the ground shaking.

Traditionally, the suspended mass was a pendulum, but most modern seismometers work electromagnetically.

A large permanent magnet is used for the mass and the outside case contains numerous coils of fine wire.

Movements of the magnet relative to the case generate small electric signals in the wire, which can be sent to a computer or recorded onto paper to create a seismogram.

Seismographs can detect quakes that are too small for humans to feel. During an earthquake, ground-shaking seismic waves radiate outward from the quake source, called the epicenter.

Different types of seismic waves travel at different speeds and through different parts of the Earth during a quake.

The farther seismic waves get from their source, the weaker they become. A network of interconnected seismographs can quickly pinpoint the source of a quake by measuring differences in the time it takes different seismic waves to reach a detector.

Because seismographs can only measure movement in one direction, many seismograph stations have multiple seismographs to record the north-south, east-west, and vertical motions of the ground.

These measurements allow scientists to estimate the distance, direction, magnitude, and the type of earthquake that just occurred.

hope it helps