# earthquake epicenter- triangulation worksheet

```Name: ________________________________
Class: _________
1. Every year there are _________________ of earthquakes around the worlds.
2. Earthquakes happen when the ____________ move.
3. The Earth’s surface is floating on ______________ rock inside the Earth.
4. As the plates move, they crack. The cracks are called _________________.
5. A _____________________ records ground shaking and prints out a
seismograph of the data.
6. In the homemade seismometer experiment, the marble falls
______________________________________________________________
____________
7. Lava is molten rock located...
a. inside the Earth
b. on the Earth’s surface
c. in outer space
8. Seismologists find the ______________ of an earthquake by using the data
from 3 different seismometer stations.
9. The ____________ Scale compares the size of one earthquake to the size of
another.
10. When the ground moves 10 times as much, there is about _________ times as
much energy released.
EARTHQUAKES
How to find an epicenter using triangulation
Locating Earthquakes
1. Difference between arrival times of P and S waves is determined. This gives
distance to the epicenter from the seismograph.
2. Three seismographs are triangulated to give actual location of the epicenter
(Figure above).
http://geology.csupomona.edu/drjessey/class/Gsc101/Earthquake.html
Practice with Triangulation: Locating an earthquake epicenter
You learned that seismologists determine the distance to the earthquake epicenter using the difference
between S and P wave arrival times. To locate the epicenter of the earthquake, seismologists use the
distance data from 3 different seismographs, and then draw circles that distance away from the
station. Where they intersect, that’s the epicenter!! (or close to it)

An earthquake was recorded at Stations A, B, and C shown on the map below.
Station A reported that the epicenter of the quake was 1500 km from the station.
Station B reported a distance of 3500 km.
Station C reported a distance of 5000 km.
Using a ruler, compass, and the scale below of ¼ inch = 500 km, locate and label the epicenter of the
earthquake on this map.
¼ inch = 500 km

An earthquake was recorded at Stations A, B, and C shown on the map below.
Station A reported that the epicenter of the quake was 2500 km from the station.
Station B reported a distance of 5000 km.
Station C reported a distance of 6750 km.
Using a ruler, compass, and the scale below of ¼ inch = 500 km, locate and label the epicenter of the
earthquake on this map.
¼ inch = 500 km
Practice with Triangulation: Locating an earthquake epicenter
You learned that seismologists determine the distance to the earthquake epicenter using the difference
between S and P wave arrival times. To locate the epicenter of the earthquake, seismologists use the
distance data from 3 different seismographs, and then draw circles that distance away from the
station. Where they intersect, that’s the epicenter!! (or close to it)

An earthquake was recorded at Stations A, B, and C shown on the map below.
Station A reported that the epicenter of the quake was 2000 km from the station.
Station B reported a distance of 2000 km.
Station C reported a distance of 4500 km.
Using a ruler, compass, and the scale below of ¼ inch = 500 km, locate and label the epicenter of the
earthquake on this map.
¼ inch = 500 km

An earthquake was recorded at Stations A, B, and C shown on the map below.
Station A reported that the epicenter of the quake was 5500 km from the station.
Station B reported a distance of 4000 km.
Station C reported a distance of 1000 km.
Using a ruler, compass, and the scale below of ¼ inch = 500 km, locate and label the epicenter of the
earthquake on this map.
¼ inch = 500 km
```