Please answer ASAP 75 Points All over the Earth, seismographic stations keep their instruments operating all the time. By timing the arrival of P waves and S waves, scientists at each station can tell how far their station is from the source of any earthquake. That distance is used as the radius of a circle around the station on a map of the world. The radius is the distance from the center of the circle to any point on the circle. By comparing the distance from several stations, seismologists can locate the earthquake’s epicenter.

Look at the map. Notice that the three circles overlap. The location where they overlap is the approximate epicenter of the earthquake.

Find the length of the radius of each circle. To calculate the radius, multiply the distance from the epicenter by 2, and then divide by 1,000 km. Use the numbers in the chart below.

Seismograph records were obtained from an earthquake in Central America. Using the information in the table, locate the epicenter on the map. On this map, 1 cm is equal to 1,000 km.

Location of Station Time Between Arrival of P and S Waves Approximate Distance from Epicenter Length of Radius of Circle (in cm)
Buenos Aires 1 min, 50 sec 1,600 km
Lima 3 min, 45 sec 2,400 km
Brasilia 4 min, 5 sec 2,880 km

1. What city is near the epicenter? (Look at the Map and find the spot that is triangulated.)

2. List the properties of P waves and S waves.

3. What conclusion would you draw if a seismogram from a particular seismic station showed only P waves?

4. Why is it better to use data from three or more seismic stations to find the epicenter of an earthquake?