Pick from:
(I) researchers
(II) houses
(III) the moon
(IV) epicenter

Answer the following question given this paragraph: One seismogram indicates the distance to the epicenter. This is determined by the P-and S-wave arrival times. If a quake is near the seismograph, the S-waves arrive shortly after the P-waves. If a quake is far from the seismograph, the P-waves arrive long before the S-waves. The longer the time is between the P-and S-wave arrivals, the further away the earthquake was from the seismograph. First, seismologists calculate the arrival time difference. Then they know the distance to the epicenter from that seismograph. Q: One seismogram indicates the distance to the what? A:
Answer:
(IV)