"Seismograms come in handy for locating earthquakes too, and being able
to see the *P wave* and the *S wave* is important. You
learned
how P & S waves each shake the ground in different ways as they
travel
through it. P waves are also faster than S waves, and this fact is what
allows us to tell where an earthquake was.

To understand how this works, let’s compare P and S waves to lightning and thunder. Light travels faster than sound, so during a thunderstorm you will first see the lightning and then you will hear the thunder. If you are close to the lightning, the thunder will boom right after the lightning, but if you are far away from the lightning, you can count several seconds before you hear the thunder. The further you are from the storm, the longer it will take between the lightning and the thunder.

P waves are like the lightning, and S waves are like the thunder. The P waves travel faster and shake the ground where you are first. Then the S waves follow and shake the ground also. If you are close to the earthquake, the P and S wave will come one right after the other, but if you are far away, there will be more time between the two.

By looking at the amount of
time
between the P and S wave on a seismogram recorded on a seismograph,
scientists can tell how far away the earthquake was from that location.
However, they can’t tell in what direction from the seismograph the
earthquake was, only how far away it was. If they draw a circle on a
map
around the station where the *radius* of the circle is the
determined
distance to the earthquake, they know the earthquake lies somewhere on
the
circle. But where?"

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*triangulation* to determine
exactly where the earthquake was. It is called triangulation
because a triangle has three sides, and it takes three seismographs to
locate an earthquake. If you draw a circle on a map around three
different
seismographs where the *radius* of each is the distance from
that
station to the earthquake, the intersection of those three circles is
the
*epicenter*!"

What is the method of triangulation used for?

Mapmaking: 0 votes (0%)

Locating earthquake epicenters: 2 votes (100%)

Locating an object in space: 0 votes (0%)

Radio Global Positioning: 0 votes (0%)

All of the above: 0 votes (0%)

Total Votes: 2