22) Which of the following statements best describes the overall motion of GPS station ALBH from 2004 to 2012? a) Steady eastward movement ▶▶▶▶b) For every few steps to the east, one step back to the west c) Moving eastward but with pauses when the motion stops 23) Based on what you have already learned, is the overall eastward movement of station ALBH surprising given its proximity to the plate boundary shown in Figure 5? Describe why you think so. This is unlikely to be surprising given the ideas covered in the lab so far. The most appropriate answer is as illustrated in the animation (http://bit.ly/2rd0706), where onshore GPS stations “no”, are predicted to move eastward during subduction in this region. 24) Describe one possible explanation (Claim) for the episodes of westward movement in this region? Given Parts 1 and 2 of the exercise students may conclude that earthquakes are a likely cause. Rebound of stresses accumulated from the convergence of the plate boundaries, and resulting earthquakes, could explain the periodic westward motion. One issue with this explanation is that earthquakes occur over short time scales and this westward motion appears to occur over weeks or months. Another issue is that earthquakes also occur during the time periods of eastward movement (anticipated answer as a segue into the next portion of this activity). 25) Over what sort of time period does this Westward movement appear to occur? a) Years ▶▶▶▶b) Months c) Weeks d) Hours e) Minutes 26) Based on your exploration of Part 1 and Part 2 of this exercise, you may have reasoned that earthquakes caused these episodes of westward displacement. Test this claim by using the IRIS earthquake browser ( to collect evidence during a period of time when the station moves westward. For example, you might try a time period from 3/1/2008 to 9/30/2008 (). Use the space below to list evidence that you could use to support or refute the claim (e.g., number of quakes, magnitude of quakes, location of quakes, times of quakes, etc.).
22) Which of the following statements best describes the overall motion of GPS station ALBH from 2004 to 2012? a) Steady eastward movement ▶▶▶▶b) For every few steps to the east, one step back to the west c) Moving eastward but with pauses when the motion stops 23) Based on what you have already learned, is the overall eastward movement of station ALBH surprising given its proximity to the plate boundary shown in Figure 5? Describe why you think so. This is unlikely to be surprising given the ideas covered in the lab so far. The most appropriate answer is “no”, as illustrated in the animation (http://bit.ly/2rd0706), where onshore GPS stations are predicted to move eastward during subduction in this region. 24) Describe one possible explanation (Claim) for the episodes of westward movement in this region? Given Parts 1 and 2 of the exercise students may conclude that earthquakes are a likely cause. Rebound of stresses accumulated from the convergence of the plate boundaries, and resulting earthquakes, could explain the periodic westward motion. One issue with this explanation is that earthquakes occur over short time scales and this westward motion appears to occur over weeks or months. Another issue is that earthquakes also occur during the time periods of eastward movement (anticipated answer as a segue into the next portion of this activity). 25) Over what sort of time period does this Westward movement appear to occur? a) Years ▶▶▶▶b) Months c) Weeks d) Hours e) Minutes 26) Based on your exploration of Part 1 and Part 2 of this exercise, you may have reasoned that earthquakes caused these episodes of westward displacement. Test this claim by using the IRIS earthquake browser ( to collect evidence during a period of time when the station moves westward. For example, you might try a time period from 3/1/2008 to 9/30/2008 (). Use the space below to list evidence that you could use to support or refute the claim (e.g., number of quakes, magnitude of quakes, location of quakes, times of quakes, etc.).
student_worksheet_key_ets.docx