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+--- Thread: Santa Barbara Channel faulting (/showthread.php?tid=221)
Santa Barbara Channel faulting - Island Chris - 04-11-2015
Hi all,
I'm giving a talk at USGS Santa Cruz on Friday, and a double figure and abstract is at:
http://walrus.wr.usgs.gov/seminar/
It comes right up now, but later it will slide down a level and presumably you will have to click on "see a list of all seminars previously presented". In the unlikely a Bay area poster here wants to see it, I assume it is public because it is online and gives directions. I'm not a gifted speaker, so if it was me deciding whether to go, I'd go if I was already in Santa Cruz, but not drive across the terrifying Route 17 across the Santa Cruz Mountain.
The fault map and seismic reflection profile are both in two-way time. In shallow water, 4 seconds TWT is about 6 km depth.
This is the blind (oblique) thrust fault system that is a huge hazard to Ventura, Santa Barbara, Goleta, and especially the UCSB campus. There is a debate on whether it is capable of M8.0 earthquakes. I tend to think not quite that big: the historic quakes have topped out at M 6 1/2, but could easily pull off a M7+, just by fault area.
Chris (aack, my cover is blown!...but long-time posters know who I am).
RE: Santa Barbara Channel faulting - Skywise - 04-12-2015
(04-11-2015, 11:58 AM)Island Chris Wrote: Hi all,
I'm giving a talk at USGS Santa Cruz on Friday, and a double figure and abstract is at:
http://walrus.wr.usgs.gov/seminar/
I wonder if the general population would like to know about these faults? When most people think of "The Big One" in LA, they think "San Andreas". Some might be aware that there are other faults around. But, I doubt many know about these offshore faults that come with a serious tsunami risk. I wonder if the local authorities should be talking about tsunami alerts and evacuation routes along the Santa Barbara beaches. Or am I over-estimating the risk?
(04-11-2015, 11:58 AM)Island Chris Wrote: Chris (aack, my cover is blown!...but long-time posters know who I am).
We all know it was you in the bunny suit!!! (just made that up
)Brian
RE: Santa Barbara Channel faulting - Island Chris - 04-13-2015
Hi Brian,
I think there is some public knowledge of some of the offshore faults, and since Tohoku, or maybe before, there are tsunami signs at the coasts at UCSB, and even back near the Santa Barbara airport, which filled a salt marsh on part. There was a tsunami from the second 1812 southern California quake (although no agreement on what fault broke). There was a local tsunami from the 1927 Lompoc quake.
Chris
RE: Santa Barbara Channel faulting - Skywise - 04-13-2015
(04-13-2015, 10:35 AM)Island Chris Wrote: Hi Brian,
I think there is some public knowledge of some of the offshore faults, and since Tohoku, or maybe before, there are tsunami signs at the coasts at UCSB, and even back near the Santa Barbara airport, which filled a salt marsh on part. There was a tsunami from the second 1812 southern California quake (although no agreement on what fault broke). There was a local tsunami from the 1927 Lompoc quake.
Chris
I did not know there were already signs. That's good there's some awareness.
You mentioning tsunami reminded me, I recall now there is concern that it's not just due to fault action, but due to underwater landslides. Those of course can make for large very local tsunami, right?
Brian
RE: Santa Barbara Channel faulting - Island Chris - 04-16-2015
Sure, underwater slides can cause tsunamis, including adding to the amplitude of one form a quake. But, if the slide is big enough, these can be giant ocean-crossing ones. For example, some think that a collapse of one of the Canary Islands caused marine deposits at up to 23 m elevation in Bermuda (which presumably is not uplifting, so had to be something like that if the global sea level was not much higher than today).
Working on my talk...at 4:45 AM, but am jet-lagged.
Chris