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Originally posted by westcoast
Okay, so I felt compelled a couple of days ago to put together a map indicating where we have had 6+ quakes along the cascadia subduction zone in recent history. I finally did it today. This info took several hours to wade through, but it paints a compelling picture.
Using USGS info, I went back ten years and made a list of all significant quakes along the West coast, including Alaska and Canada. It wasn't long before the different faults and depths became obvious. Although I think that the quakes in Alaska are tied into our cascade subduction zone it is not techinically considered the same so I am not including it on the map. However, I think it important to note that there have been MANY (nine to be exact) of 6+ and 7+ quakes in that region over the past ten years. My point being that quite a bit of pressure has been rleased, ruptures occuring. A stark comparison to our own region.
I could clearly see what quakes belonged to the San Andreas, the Juan De Fuca and the infamous Cascadia subduction. I threw out the Andreas and De Fuca for obvious reasons and then limited the quakes to only 6+ in mag. I want to add though, that even extending the range down to 4.0, there have only been a handful along the coast North of California in the past decade. Surprising.
SO....this is the map I came up with using those parameters:
I marked the 6+ quakes with red squares, then connected those dots with a red line. I added a few other note-worthy quakes of lower mags (4+) in orange, since I thought it obvious they also originated from the subduction zone, based on location and depth. I connected those dots with yellow to give what I think is a rather complete picture of where the next rupture is going to occur.
I then drew in where I feel the most destruction and motion will occur, using grey lines:
(please keep in mind we are talking a 9+ quake. the grey area is only where the most would occur but the damage will be massive and widespread)
Then I added the most likely subsequent tsunami damage:
(Obviously, this applies to canada too....but I limited the map to the US)
That the subduction zone is due for a mega thrust earthquake is not in question. Most scientist agree that it is a matter of when not if and that the when is most likely to be from now to the next 20 or 30 yrs. The less pressure being released, the more ominous it gets...indicating the 'lock' is increasing, thus the pressure.
I have talked a lot about the deep tremors. I want to post a couple of maps to show you why. Keep in mind that the deep tremors were first discovered back in 2001 and they began studying them a year or two later. It has been determined that it is a slow tremor and slip process, releasing around the equivalent energy of a 7.0 quake each year. It is a good thing, probably. Truth is they don't know for sure, but it makes sense to me that if we aren't having the quakes, the deep tremors are a good alternative. What concerns me is that they were chugging along up until the Japan quake. Since then, there have been hardly ANY in comparison. We also haven't seen any even moderate quakes in response. I don't like that.
Here is a map I did back on 3/17 showing how many tremors there had been in just the first three months of 2011. It clearly shows the subduction zone:
In contrast, here is one I just did showing post-quake until now. Note that almost half of those happened the three days following the Japan quake. There haven been almost none since then:
SOURCE
Also note that most of them have been on the southern end of the subduction zone. I don't like that either. Mother nature likes balance....which is why the silence here since the Japan quake has me on edge. It think it means one of two things:
A. The Japan quake relieved the pressure from the casadia subduction zone - or-
B. The Japan quake increased the pressure, thereby locking it up even more
Based on history, I have to go with option B, although I don't want to.
Look at the map. There has been only ONE quake in Washington that was greater than 6.0 in over a decade.
NONE in or near Oregon in over a decade.
Something has got to give.edit on 11-4-2011 by westcoast because: (no reason given)
Do you think that if the array were to extend below that it would show something? Say......a whole heck of a lot of tremors right at the Cali/Nevada border????
Originally posted by oppaperclip
Can you imagine the unrivaled destruction of a caldera in Washington and Yellowstone erupting at the same time? If the San Andreas fault goes a tumblin in a spectacular way I don't want to be near anything that has to do with the north west.