Reading a Seismograph

 If a P-wave arrives at station A at 9:08, how do we correctly write the time? ________ : _________ : ________  If an S-Wave arrives at station A at 9:15, how do we correctly write the time? ________ : _________ : ________

 AIM: How can you use a graph of earthquake waves’ travel distance and time to find an epicenter?  Learning Target: I can use observational data to solve for the earthquake epicenter.  Agenda Catalyst Mini lesson Practice

 An instrument that measures motion beneath the ground

 Time is on the X axis

 Step 1: When do S waves arrive?  S arrives at: 9:15

 Step 2: When do P waves arrive?  P arrives at: 9:08

 Step 3: What is the difference in arrival times?  Find the difference  9:15  -9:08  7 minutes

 Steps:  1. Find difference in arrival time  2. Using the graph, make a mark on your paper  3. slide your paper VERTICALLY until that mark matches the space in between  4. Read the x – axis to find the distance.

Example: If the difference in arrival time between P and S waves is 7 minutes and 00 seconds, how far away did the earthquake begin?

Difference in Arrival Time Distance from Epicenter 7:00 minutes

Example: If the difference in arrival time between P and S waves is 2:40, how far away did the earthquake begin?

Difference in Arrival Time Distance from Epicenter 7:00 minutes5.0x10 3 Km 2:40 minutes

S-waves: ___9 ____ : ____27_____ : ___00___ P-waves: ____9___ : ____24_____ : ___00___ Difference: _______ : _________ : ______ Distance: _____________ kmS

S-waves: _______ : _________ : ________ P-waves: _______ : _________ : ________ Difference: _______ : _________ : ________ Distance: _____________ km

 Inclass and Complete if not finished: Complete the Page in Your Unit Packet Labeled:  Finding Epicenters  ONLY DO SIDE 1