MM+post+assessment+ligo

back

**1. Use Google Maps (or Google Earth—your pick) to calculate the distance from the quake’s epicenter to LIGO.**
 The quake occurred near Pakistan, which is approximately 10,912.9617 kilometers. I plugged the coordinates (34.5390, 73.5880) into Google Maps and drew a line from the Quake's epicenter to the LIGO base. It was 6781 miles away which transfers to 10,912.9617 kilometers.

**2. Calculate the seismic wave speed twice, once for each of the LIGO plots shown.**
 1. Using the Seismic Y Graph:   You need to divide the distance by the time it took to get from it's origin to LIGO. It occurred at 3:50:40.80, and hit LIGO at approximately 4:12. This means that it took about 22 minutes 20 seconds, or 1340 seconds to get around the world.  So using the distance (10,912.9617km) you would divide it by the time (1340sec) to get the wave speed.  -->(10,912.9617km)/(1340sec)= **8.144km/s**<--    2.Using the Seismic Z Graph: You need to do the same thing as above, divide the distance by the time it took to get around the world. The earthquake again occurred at 3:50:40.80 and on the Z graph it arrived a little earlier, around 4:09. This means it took 19 minutes and 20 seconds to get to LIGO, or 1160 seconds.  -->(10,912.9617km)/(1160sec)= **9.408km/s**<--

**3. Comment on any difference you see between the LIGO plots, and between the wave speed estimates obtained using each plot.**
 The Y graph seems to have received the earthquake a bit later, making the speed of the wave more than a kilometer/second slower, and the Z graph received it faster (at 4:09 as oppose to 4:12) so it made the speed of the wave faster. The Z graph also seems to have picked up more of the earthquake, or another earthquake altogether. <span style="font-family: Tahoma,Geneva,sans-serif"><span style="font-size: 90%; font-family: 'Comic Sans MS',cursive"><span style="font-family: 'Comic Sans MS',cursive"><span style="font-family: 'Courier New',Courier,monospace"> <span style="font-family: Tahoma,Geneva,sans-serif"><span style="font-size: 90%; font-family: 'Comic Sans MS',cursive"><span style="font-family: 'Comic Sans MS',cursive"><span style="font-family: 'Courier New',Courier,monospace"> According to the Data Channel for I2U2, "the actual sensor from which the measurements were obtained. Keep in mind that some stations have several related sensors. Each seismometer, tilt meter and magnetometer actually has three sensors for the three independent directions, x, y, and z." So this would lead me to believe that the reason that the earthquake appeared a bit earlier on the Z Graph is because it traveled in a different direction than the Y Graph, so it appeared at different times. This means that the wave speed may have been the same, even though in the above equations you can see that the Z graph went faster, but since we now know that all of the different sensors have three independent directions, perhaps the Z graph took a shorter route to LIGO and thus was picked up quicker. <span style="font-family: Tahoma,Geneva,sans-serif"><span style="font-size: 90%; font-family: 'Comic Sans MS',cursive"><span style="font-family: 'Comic Sans MS',cursive"><span style="font-family: 'Courier New',Courier,monospace"> <span style="font-family: Tahoma,Geneva,sans-serif"><span style="font-size: 90%; font-family: 'Comic Sans MS',cursive"><span style="font-family: 'Comic Sans MS',cursive"><span style="font-family: 'Courier New',Courier,monospace"> One reason that the waves traveled in different directions is because there are four different types of waves. Two of which I will mention. P-Waves are waves taht can travel through gasses (such as sounds), elastic solids and liquids, including the Earth, and S-Waves are traveling through the surface. According to the Purdue Wave Data page, S waves travel slower than P-Waves in a solid and, therefore, arrive after the P-Wave. So that being said, it would make sense that the Z-Graph was a P-Wave. There are also L-Waves and R-Waves; which stand for Love waves and Rayleigh waves, respectively. <span style="font-size: 90%; font-family: 'Comic Sans MS',cursive"><span style="font-family: 'Comic Sans MS',cursive"><span style="font-family: 'Courier New',Courier,monospace"> <span style="font-size: 90%; font-family: 'Comic Sans MS',cursive"><span style="font-family: 'Comic Sans MS',cursive"><span style="font-family: 'Courier New',Courier,monospace"> <span style="font-size: 90%; font-family: 'Comic Sans MS',cursive"><span style="font-family: 'Comic Sans MS',cursive"><span style="font-family: 'Courier New',Courier,monospace"> Info taken from [|here], [|here], and [|here]. <span style="font-size: 90%; font-family: 'Comic Sans MS',cursive"><span style="font-family: 'Comic Sans MS',cursive"><span style="font-family: 'Courier New',Courier,monospace"> <span style="font-size: 90%; font-family: 'Comic Sans MS',cursive"><span style="font-family: 'Comic Sans MS',cursive"><span style="font-family: 'Courier New',Courier,monospace">