SES4U- Earth and Space science Epicenters Assignment | All Answwers are Correct

Help Wanted: Seismologist Introduction: How do seismologists determine the location of an earthquake from seismograms? By using triangulation you will be able to determine the epicentre of the earthquake. You will use four seismograms to determine the location of the earthquake’s epicentre, and you will determine the magnitude of the earthquake. Part A: Determining Epicentre: a. On the first seismogram, use the second scale on the bottom to determine the P-S lag time (difference in time between the P and S waves). Record the value in table 1. b. Calculate the distance to the epicentre. In eastern Canada, P-wave velocity = 6.2km/s and S-wave velocity = 3.65km/s, a difference of 2.55km/s. The distance in km from the epicentre to the seismic station could then be calculated using the following formula: D = 22.63T/2.55, where T is the lag time between the P and S waves. c. Repeat this procedure for all of the stations. d. For each seismogram, draw a circle on the map with the compass, using the distance you calculated as the radius of the circle. Place the point of the compass at zero on the map scale and adjust the compass width to the calculated distance. With the distance set, place the point of the compass on the station, and draw a circle. e. Repeat, setting the compass and drawing circles for all four stations. f. The area where all the circles intersect is the epicentre. Part B: Determine the magnitude: