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Re: Cascadia Earthquake and RR Tsunami Scenario
Author: BOB2
Date: 10-11-2014 - 14:25
It's not at all unlikely that a Cascadia tsunami could potentially do substantial damage to Humboldt Bay, it's a very low barrier, and there is geological evidence of some pretty good sized tsunami's hitting the upper northwest coast, miles inland over low lying areas, just like Japan.
The comments on the coming end of SMART, the NWP, and its connections from tsunami may be a little overboard, though. Something about Mt. Tam protecting most of the Bay from a direct Northwest Pacific hit makes me think that is not likely. The Bay could see some big tidal fluctuation from a big tsunami, which could cause localized damage along the shore, but not the effects of an unobstructed frontal wave, or worse a direct hit from waves forced into a small shallows which can force the water way inland.
On the other hand, you may not want to be at the far end of the N Line when a Cascadia tsunami hits that side of SF.
I once went to an interesting tsunami planning meeting representing transit, and was asked how long it would take to mobilize buses and begin to evacuate low lying areas, and of course, the question I asked back was, what kind of warning would we get...?
Southern California's most likely tsunami flooding scenarios are for a five to twenty foot tsunami from a 7+ in the Santa Barbara Channel. Sou Cal is around Point Conception and partially blocked by the outer islands from a direct hit from an Alaska/Cascadia tsunami source, but because of the distance from those events it would give you at least an hour or two minimum warning time, and you could move a lot of people out of the way. A Channel Island tsunami would potentially hit low lying areas like Oxnard, Marina Del Rey, or Newport and Huntington Beach within as little as 5 or 10 minutes.
I recommended that our evacuation plan in that case was to yell very loudly-run for high ground. Thankfully, these smaller potential tsunamis would not go far inland, and only a few locations are at much risk (generally where you now see most of the evacuation route signs).
Sou Cal tsunami damage to RR infrastructure could threaten a number of low lying points along the LOSSAN corridor and potentially do some serious damage. But, RR's, and RR infrastructure like tunnels and bridges have done real well in the quakes themselves, and are more at risk of short term disruption, due to things like damaged or collapsing highway infrastructure. Chatsworth was a great example of that danger, where there was an initial fear of structures above the line collapsing, but no damage to the AV line or tunnel, which became a vital link to Santa Clarita and the AV during the 5/14 interchange reconstruction.
The comments on the coming end of SMART, the NWP, and its connections from tsunami may be a little overboard, though. Something about Mt. Tam protecting most of the Bay from a direct Northwest Pacific hit makes me think that is not likely. The Bay could see some big tidal fluctuation from a big tsunami, which could cause localized damage along the shore, but not the effects of an unobstructed frontal wave, or worse a direct hit from waves forced into a small shallows which can force the water way inland.
On the other hand, you may not want to be at the far end of the N Line when a Cascadia tsunami hits that side of SF.
I once went to an interesting tsunami planning meeting representing transit, and was asked how long it would take to mobilize buses and begin to evacuate low lying areas, and of course, the question I asked back was, what kind of warning would we get...?
Southern California's most likely tsunami flooding scenarios are for a five to twenty foot tsunami from a 7+ in the Santa Barbara Channel. Sou Cal is around Point Conception and partially blocked by the outer islands from a direct hit from an Alaska/Cascadia tsunami source, but because of the distance from those events it would give you at least an hour or two minimum warning time, and you could move a lot of people out of the way. A Channel Island tsunami would potentially hit low lying areas like Oxnard, Marina Del Rey, or Newport and Huntington Beach within as little as 5 or 10 minutes.
I recommended that our evacuation plan in that case was to yell very loudly-run for high ground. Thankfully, these smaller potential tsunamis would not go far inland, and only a few locations are at much risk (generally where you now see most of the evacuation route signs).
Sou Cal tsunami damage to RR infrastructure could threaten a number of low lying points along the LOSSAN corridor and potentially do some serious damage. But, RR's, and RR infrastructure like tunnels and bridges have done real well in the quakes themselves, and are more at risk of short term disruption, due to things like damaged or collapsing highway infrastructure. Chatsworth was a great example of that danger, where there was an initial fear of structures above the line collapsing, but no damage to the AV line or tunnel, which became a vital link to Santa Clarita and the AV during the 5/14 interchange reconstruction.
