1.B 2.D 3.A 4.C
im not sure to my answer, correct me if i wrong.
determine the distance
hinde ko alam need kolqng ponts sorry
How Do I Locate That Earthquake's Epicenter?
To figure out just where that earthquake happened, you need to look at your seismogram and you need to know what at least two other seismographs recorded for the same earthquake. You will also need a map of the world, a ruler, a pencil, and a compass for drawing circles on the map.
Here's an example of a seismogram:
FIGURE 1 - OUR TYPICAL SEISMOGRAM FROM BEFORE, THIS TIME MARKED FOR THIS EXERCISE (FROM BOLT, 1978).
One minute intervals are marked by the small lines printed just above the squiggles made by the seismic waves (the time may be marked differently on some seismographs). The distance between the beginning of the first P wave and the first S wave tells you how many seconds the waves are apart. This number will be used to tell you how far your seismograph is from the epicenter of the earthquake.
Finding the Distance to the Epicenter and the Earthquake's Magnitude
FIGURE 2 - USE THE AMPLITUDE TO DERIVE THE MAGNITUDE OF THE EARTHQUAKE, AND THE DISTANCE FROM THE EARTHQUAKE TO THE STATION. (FROM BOLT, 1978)
Measure the distance between the first P wave and the first S wave. In this case, the first P and S waves are 24 seconds apart.
Find the point for 24 seconds on the left side of the chart below and mark that point. According to the chart, this earthquake's epicenter was 215 kilometers away.
Q1 - 9000km
Q2 - Locating earthquake epicenters will pinpoint which fault lines are active. Usually, the less active fault line stores great amount of energy (potential energy) that may cause a major earthquake once it is released. Ergo, places near fault lines that remained inactive for a long period of time are expected to experience major earthquakes.