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The above seismograms were recorded at 4 samples per second from a Guralp CMG-3TD broadband seismometer in the walk in vault near Leonard, OK. Leonard is i4060 kilometers or 2520 miles from the epicenter (great circle) P-WAVE ARRIVAL BLOWUP This blowup of the P-wave arrivals (the first wave to arrive) can be used to determine the direction to the earthquake. The initial movement at Leonard could be either away from the earthquake epicenter or toward the epicenter. The direction would depend on the direction of fault movement. The vertical initial movement shown on bhz (z is always used for vertical components) is distinctly downwards. At Leonard, the earth is moving toward the Columbia epicenter (down). The North-south trace (bhn) moves southward, and the east-west trace moves eastward (on seismograms upward movement of a trace shows earth movement up, north, or east). The inital movement shows that the earth moves toward the epicenter AND to the southeast. Therefore the earthquake was SE of Leonard. Most of South America is E of North America. The Colombian Andes are SE of Oklahoma. We know the direction. From the time lag of the S wave after the P wave (you measure it) we can find the distance. Thus from this one three-component seismogram, we can locate the earthquake within at least the right country. Use this travel time graph of P PP and S to find the distance