3 ms·
A shallow 6 is very different from a deeper 7. My city Christchurch was fucked by a 6.2 or 6.3 - but it was both (a) shallow (5km) and (b) close to dense resid
by robocat 3y ago
A shallow 6 is very different from a deeper 7.
My city Christchurch was fucked by a 6.2 or 6.3 - but it was both (a) shallow (5km) and (b) close to dense residential areas.
Christchurch was near to the 7.1 Canterbury earthquake but that did much less damage as it was 10km deep and Christchurch wasn't on top of it (it mostly affected less dense rural properties in the region near Christchurch).
Be careful not to think of earthquakes as a point - talking about epicentres and precise depth is very misleading. Earthquakes are a fault-sheet or wrinkles. Surface fault lines only show where the 3D rips through the solid earth meet the surface. Fault lines matter a bit especially since they indicate local shallowness, but I suspect we get distracted by them because they make spectacular news reports. Reality is complex.
My parents house was right above the fault plane of the Canterbury fault - and their house came though mostly okay. I know lots of people very near the Christchurch quake and many of their houses were unrecoverably damaged.
- lamontcg 3y agoThe Nisqually quake in Seattle was a 6.8 but it was 57km (35 miles) deep. It was also on the other side of Tacoma sort of in between Tacoma and Olympia. The depth of that quake made it a lot less severe than it could have been, only killed one person, but estimated it cost $1b to $4b in damages.
- thijson 3y agoI remember how it felt, I thought I was sick, because I felt this rocking motion. I thought it was just me, then I stood up and saw a plant shaking, so I knew it was everything else that was shaking too. The amplitude slowly increased, reached a maximum, then decreased over the course of what seemed like a minute. It was a quite slow frequency, possibly due to the depth. This was from Portland.
- lamontcg 3y agoI was on the 8th floor of a brick building in Seattle. If it had been a shallow quake I would be dead. There was a whole lotta motion. Can't remember what it damaged, though, other than some glass bottles on top of the refrigerator that fell off and shattered everywhere in the kitchen.
- RowanH 3y agoThere's actually some interesting visuals that illustrate this showing the difference in ground velocity between the two earthquakes : 2010 Quake: https://www.youtube.com/watch?v=eA5m5PZ5p8E https://www.youtube.com/watch?v=eA5m5PZ5p8E 2011 Quake: https://www.youtube.com/watch?v=KJW7tkTwqXo https://www.youtube.com/watch?v=KJW7tkTwqXo And a good explanation vid: https://www.youtube.com/watch?v=aaA1nxYVi6k https://www.youtube.com/watch?v=aaA1nxYVi6k
- EdwardDiego 3y agoIIRC another aspect was that the fault-line that did Feb 22 was underneath the Port Hills, and the volcanic rock deflected the energy towards the city.