A couple. You need to find where the tremors are coming from, basically which graph has the strongest reading even when you move it's location.
3
3 stations
There are many probably earthquake precursors that could lead to useful predictions of when one will occur. Foreshocks are one way to predict when a quake is coming.
Three
Measurements from at least three different seismometer stations are required to locate an earthquakes epicentre. For more information see the related question.
three
Three sizemographs are needed to accuratley locate the earthquake's epicentre, the way to work it out is you draw three radi from the siesmographs to where the earthquake roughly is then you draw circles from that, the point where the three circles overlap is the epicentre.
3
3 stations
At many different earthquake centers. When an earthquake happens the tree nearest earthquake centers record the magnitude and intensity of the seismic waves produced by the earthquake in order to find the origin or epicenter
You would need at least three different seismometer locations to triangulate an earthquake's location.
There are many probably earthquake precursors that could lead to useful predictions of when one will occur. Foreshocks are one way to predict when a quake is coming.
At least three.Please see the related question for an explanation as to why.A minimum of three seismograph or seismometer stations are required to locate the epicentre of an earthquake.
3
Three
Measurements from at least three different seismometer stations are required to locate an earthquakes epicentre. For more information see the related question.
300,000 needed hospital treatment because they were injured