During one earthquake, seismic waves space sent almost everywhere the globe. Despite they may weaken through distance, seismographs space sensitive sufficient to tho detect this waves. In order to recognize the ar of one earthquake epicenter, seismographsfrom at the very least three different places are essential for a particular event. In figure 13.9, over there is an instance seismogram from a terminal that contains a boy earthquake.

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Once 3 seismographs have actually been located, discover the time interval between the arrival of the P-wave and the come of the S-wave. First, identify the P-wave arrival, and read down to the bottom the the seismogram to note at what time (usually marked in seconds) that the P-wave arrived. Then perform the exact same for the S-wave. The come of seismic waves will certainly be recognized by rise in amplitude – look for a pattern readjust as lines get taller and an ext closely spaced (ex. Number 13.10).


By looking at the time between the arrivals of the P- and also S-waves, one can determine the distance to the earthquake from the station, with much longer time intervals indicating longer distance. These distances are established using a travel-time curve, i beg your pardon is a graph that Pand S-wave arrival times (see figure 13.11).

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Though the street to the epicenter can be identified using a travel-time graph, the direction can not be told. A circle v a radius that the distance to the quake have the right to be drawn. The earthquake arisen somewhere follow me that circle. Triangulation is compelled to determine specifically where it happened. 3 seismographs are needed. A circle is attracted from every of the three different seismograph locations, wherein the radius of each circle is same to the street from that terminal to the epicenter. The spot whereby those three circles intersect is the epicenter (Figure 13.12).

clipboard_e060e1b5bc87f9355df949aa7f413b1ec.pnghow many seismograph stations are needed to locate the epicenter of an earthquake?