Alyssa Anaya Lab 5 Earthquakes-3

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Dec 6, 2023

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Name: Alyssa Anaya Lab 5 – Earthquakes Introduction: The Cascadia Subduction Zone (CSZ) runs offshore the entire length of the Pacific Northwest; starting in Northern California and extending up into British Columbia. Named for the famous mountain range that it spawns, Cascadia also has the potential to wreak destructive earthquakes on the region. Cascadia’s geologic setting is essentially the same as that of Japan, Indonesia, and Chile; each of which had devastating earthquakes in the last two decades. Task: Gather information on the following events: 2004-Indonesia, 2010-Chile, and 2011 Japan and compare them. Questions: a) Give the Richter scale magnitude of each quake. b) Compare the amount of casualties for each. c) Were all the earthquakes accompanied by tsunamis? d) Is a tsunami the result of all types of earthquakes? Explain. Tsunamis do not accompany every earthquake. You would generally need an earthquake that’s epicenter is in or near the ocean. 2004-Indonesia 9.1 magnitude, 227,898 people dead, tsunami 2010-Chile 8.8 magnitude, 525 people dead, tsunami 2011-Japan 9.0 magnitude, 19,759 people dead, tsunami Read this website to help you with the following questions: Pacific Northwest Seismic Network-Turbidites e) What are turbidites? Turbidites are the result of deposit of sediment from a turbidity current that causes something like an avalanche of sediment that has slid down the continental slope. f) What causes them? They can be triggered by slope failures, storm induced waves, tsunamis, but typically earthquakes. g) How does the fact that the turbidites are simultaneous support the idea that earthquakes cause them?

Because the sediment found shows that it was happening at the same time as these earthquakes. We are able to see from the core samples had consistent numbers of turbidites from side and main channels. h) How do cores of ocean sediment allow us to plot the history of catastrophic earthquakes in the Pacific Northwest? We see the different sediment that has been deposited from the turbidites and the major earthquakes that occurred at the same time. i) What is the recurrence interval for a full Cascadia margin rupture? The recurrence interval for a full Cascadia margin rupture occurs every 500-600 years on average. j) When did the last one occur? The last full Cascadia margin rupture occurred in about 1700. Examine the timeline above. k) Make a general conclusion as to when the next Cascadia earthquake might strike. Using the 500-600 interval, it would be in about 2200-2300. Application: Summarize your findings about subduction zone earthquakes and compare them to explain the damage and loss of life. Would earthquakes generated on the Cascadia Subduction trench be as destructive? While researching about the subduction zone earthquakes in Indonesia, Chile, and Japan, I found that they were all very large and destructive earthquakes. The 2004 Indonesia earthquake was a 9.1 and 227,898 people died, which is incredibly devastating. The 2010 Chile earthquake was an 8.8 and 525 people died. The Japan earthquake was a 9.0 on the Richter scale, and 19,759 people died. All three were also accompanied by a tsunami especially given their epicenter's proximity to or in the ocean. All three of these regions have incredibly similar geological settings to that of the Cascadia subduction zone that runs offshore the Pacific Northwest.

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