Update: May 29, 2009
Well, we had a “big quake” that is almost a “great quake” on top of the high tide interval, just not in Northern America. It was a 7.3 quake in Honduras.
So the question is, what will next month bring? I’m still holding out for a large quake in the northern hemisphere, probably the Caliveras. Though frankly, given the Long Beach, and now this Honduras quake, the tidal impact on quake triggers is fairly clear. The big question now is how to focus it in on a particular continent, IMHO.
Update: May 18, 2009
Well, we’ve had a magnitude 3 quake near Cloverdale in northern California and a magnitude 4.7 near Long Beach. From the point of view of angular momentum, we are in a similar pattern to that of the 1930’s (as I recall the solar diagram). If the theory that there is a spin-orbit coupling that influences crustal stresses holds, then we would expect activity similar to that. This description of the Long Beach quake from the USGS site is, in that context, very spooky:
A magnitude 4.7 earthquake struck about 3 miles east of Los Angeles International airport at 8:39 p.m. (PDT) local time, at a depth of 8.5 miles. Given that the location is in a densely populated part of the Los Angeles basin, it was widely felt. Initial estimates from the USGS ShakeMap indicate that although strong shaking will have been felt by many people, damage is expected to be light.
The initial focal mechanism is consistent with slip on the Newport-Inglewood fault, which was the source of the damaging 1933 Long Beach earthquake. Three of the early aftershocks, however, are west of the Newport-Inglewood fault trend. Later aftershocks are expected to help define the fault plane that ruptured. The Los Angeles basin is crossed from northwest to southeast by the intensively studied Newport-Inglewood fault zone. In 1920, the Inglewood earthquake (M 4.9) occurred in nearly the identical location to this evening’s earthquake. The 1920 event was the original reason for identification of this as an active fault zone capable of damaging earthquakes, which then later proved to be the case in the 1933 Long Beach event. After the 1933 event, the name of the fault zone was changed to the Newport-Inglewood fault zone in recognition that it is continuous from Beverly Hills to Newport Beach.
IFF the “everything old is new again” thesis has legs, one would expect our present dinky Long Beach quake to imply a much more damaging quake sometime around 2022. Fortunately, fault line movement is not nearly so precise. We might have nothing, or we might have a great quake tomorrow. But it will be interesting to watch Long Beach for the next decade…
The tide charts do show the next few days as a high stress period (though June 18-24 or so has more stress), so once again, I’d advise folks to top up those water barrels and stock up the emergency food storage if you have not al ready.
Orbital Dynamics Can Be Bizarre
So where does the angular momentum go in this case?
I think the math for orbital motion and the potential to influence an orbiting body may be a bit more complex than expected. Now just imagine what it must be like with 9 or 10 major bodies and a few thousand minor ones…
This post was started by observations of the March 9th week. I’ve preserved that map of quakes here: March 9th Quakes in California
I was at the USGS site that week and the pattern of that week was continuing the following week (though a bit further down the fault system).
That week the activity was a bit heavier north of Hayward, but the following week we had some more activity a bit further south. Given the historical tendency for the Hayward side of the bay to let go with a big quake some years after the S.F. side (and given the Loma Prieta quake just a few years ago – in geologic time scales, at least) this is looking just a bit spooky.
The rest of this posting is in that historical context where “this week” is the week of March 9th.
9 March, 2009
I’m going to be filling my water jugs and making sure my quake kit is up to date. This is the current USGS quake map
As of Sunday night, it has a significant line of quakes headed on a line through the Hayward Calaveras system (the part that is not very active north of Berkeley this week is the part that was most lit up last week…)
This needs watching, especially if the “spin-orbit coupling” thesis that says when the sun is on top of the barycenter of the solar system we get more quakes and volcanos has any validity. I’ve lost track of exactly from whom I took the lead-in graphic. I think it was Geoff Sharp at:
But I’m not sure. If you recognize it as your product, please let me know so I can ask permission to use it ;-)
Lets just say that 2011 to 2016 is not looking very good. Given the tendency for faults to let go under the added stress of heavy tidal forces, you might want to put a tide chart on the wall. It looks like June 22 and both the start and end of December are very high tides. (September 15, 16 has a sort of high, but not quite peak, tide. Rather like right now…)