![]() ![]() I did run into a geologist a couple years ago who was working for Dept of Geology and Mineral industries and he told me he thinks the main concern is the tsunami potential, not necessarily the quake effects. If it happens it will be hell on earth, and if it happens during summer it'll have fire and brimstone to add to it as the gas and electric lines rupture and topple. Japan is likely the most prepared country for a major seismic event and they had a nightmare earthquake and tsunami as we all know. Along with the passage of measure 5 I blame for my utmost ignorance. I was born in Oregon, earthquakes were a California distinction in our schooling. I was fairly stunned when I read the New Yorker article about this in 2015. This is just from me skimming the report now - if you want to know more I bet you can really dig into that and all of the figures! Other factors are included in these class assessments too - the F areas in the Cascades, for example are hillsides with higher landslide risks (and you can see these as darker orange in the map too). These unconsolidated sediments will amplify seismic waves more than solid rocks. Take a look at a geologic map of Oregon - south of Eugene and around it, the rocks are volcanic in origin rather than the softer, unconsolidated sediments that make up a lot of the rest of the Willamette Valley. Geology plays a big part in these differences. The shape of Eugene's class B section matches the yellow patch in the figure posted. As you can see, Eugene is class B, whereas areas around it in the valley are D, some hillsides are F, etc. They go through all of the different data they use, and then show this new map of site conditions colored by the classes above (page 9). Site class F: soils susceptible to potential failure under seismic loading.Site class C: very dense soil and soft rock. ![]() They did this "by combining a statewide digital geologic map with a catalog of measured shear wave velocity values, a statewide landslide inventory (SLIDO-2 ), and data from published hazard studies." They classified sites into 6 categories (page 2 of the report): The authors calculated site condition maps for Oregon by creating a new map of shear wave velocities for different areas. If you want to get really in depth, read the whole DOGAMI report! It's a big file you can download here. It has to do with the expected intensity of ground shaking in a certain area, which relates to the underlying geology. Rule 8: No factually misleading informationĪ similar question was asked a couple months back. Rule 4: Post must have Oregon explicitly involved ![]() Rule 3: No spam or reposts + limit off topic comments Rule 2: No brigading/harassment/usernames, etc. More info about our rules and what they mean: ![]()
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