An object that measures the earth to see if there is going to be an earthquake
A seismogragh is a sensative instrument that records seismic waves.
A seismogragh and/or seismometer.
The distance to the epicentre of an earthquake and it's magnitude.
the exact distance between earth and moon
A seismograph is the reading that comes from a seismometer. They are used to measure the seismic waves that are generated by volcanoes and earthquakes.
The ground shakes moving a needle which is then used to see how strong it was based on how much the needle moved.
A seismograph uses electromagnetic sensors to measure seismic waves in order to detect earthquakes that are too small to feel, as well as detecting and tracking other phenomena.