SAUNDERS
NAME______________________________
HOUR__________________
EARTH SCIENCE
CH 6: 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
SAUNDERS
EARTH SCIENCE
NAME______________________________
HOUR__________________
CH 6: EARTHQUAKES
Practice with Triangulation: Locating an earthquake epicenter
In the 6.2 Notes, 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
SAUNDERS
EARTH SCIENCE
NAME______________________________
HOUR__________________
CH 6: EARTHQUAKES
Practice with Triangulation: Locating an earthquake epicenter
In the 6.2 Notes, 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