Friday, June 06, 2008

Breaking plates a natural event

Our friend Enigma recently raised the question about strange happenings as potential predictors of major seismic events. Her blog mused about: China 2 Hours Before The Quake… Really Strange Skies. I’m no scientist, just curious, but it did remind me of my own thoughts on major seismic predictors.

It began when I was living on top of the Juan de Fuca subduction zone in BC. If Californians are concerned about their slip faults then they would be really frantic about the subduction zone through the coast of Washington and BC, a big one there would create destructive powers way beyond anything further south.

But the series of Asian quakes, like the 2004 Indian Ocean quake had me thinking that enormous pressure must be relieved on the eastern side of the Pacific plate as the western side becomes increasingly active.

That is prediction one, sure the western Americas coastline will continue to be shaken, probably more so in the South American region. Well, observation suggests that SA is still fairly active where NA has quieted significantly.

But for how long? Well given the massive upheavals occurring around the giant Indo-Australian plate there could be a real reduction of stresses in the north eastern Pacific for centuries. The fact is, the Indo-Australian plate is in the process of breaking apart, and the adjoining African and Arabian plates are changing too.

Now prediction two is more about a potential predictor based on precursor events, or the potential to identify those signs. I’m still slowly gathering evidence, but essentially I suspect that preceding events somewhere along a plate line might give a few days warning of a big one.

Not being very scientific I had focused on the area around Antarctica. The 2004 Indian Ocean earthquake was an undersea, subduction earthquake, triggering a massive tsunami. Two days earlier there was a significant (8.1) quake just off Macquarie Island, near the Antarctic.

Of course, thinking this through, the danger is not the size of the quake but its proximity to large populations. The China quake, probably driven by stresses from the north moving Indo-Australian plate, preceded another Antarctic even a few days later. Perhaps my predictor fails on the basis that if first one occurs in a heavy population area we might only hope to save a few penguins.

I’m also curious to figure in South American events, perhaps they are related to the Indian/Southern Ocean events, making it a North South, rather than an East/West prediction model. I’m sure a computer modeling program could correlate the data we are constantly receiving. Unfortunately, lacking the skill or patience, I’m stuck with patchy observation.

4 comments:

D.K. Raed said...

living for decades in Southern Calif, I came to view earthquakes almost as background music. The Palm Springs area is particularly active. There are stories of strange animal phenomenon around any given quake, but so far nothing has ever been predicative of the NEXT quake. Farmers can tell you though, when the animals act wierd, watch out, something's coming.

Now here's something wierd: after living there awhile, being woken up so often in the night when the closet doors rattled as a quake shook through, we moved away for a few years. When we returned, for reasons I can't explain, I was NEVER asleep for another quake. I always woke up a few moments BEFORE, like as if from a bad dream and waited for the quake to happen. The only quake I ever thought was serious enough to get out of bed for was Northridge. I was up & turning on the TV as the quake hit. That was a rough one, rolling & heaving, stopping & starting again. We were probably 150-miles from the epicenter. The Landers quake was much closer. It felt more like a big POP, then rattles & rumbles. Now that we've been away for a few years, I wonder if I still have the magic touch?

Does any of your research show that more quakes happen at night, or is that just my experience?

I remember having college discussions, passionate arguments really, about whether a series of quakes portends a big one, or whether it is letting off pressure & postponing the big one. I argued the latter opinion. But I revised that after we were up in Washington State when Mt St Helens blew up because that was preceded by quake swarms.

The map you posted doesn't show NZealand. Isn't it sitting right on top of the ring of fire?

Cart said...

A friend of mine lives in San Diego and he says he wakes before a quake. Can’t say I’ve really experienced anything more than a tremor, but often they were during dark hours. Still, hard to say with a tremor and other daytime disturbances.
I have come across suggestions of mainly nighttime, or during really extreme weather – including storms and dry heat. But researchers say thee is nothing definitive.
A series of quakes can have the effect of relieving built up pressure, as can volcano activity – recalling the last Mt St Helens scare. I’m sure someone has done computer modeling on all these variables, but I haven’t found it.
New Zealand lies at the edge of both the Australian and Pacific tectonic plates and this map is too crude to show it unfortunately. But NZ was formed from the seismic activity on that part of the margin. It also has, along with Java and Yellowstone NP, a super volcano. Sometimes NZs daily quakes are felt as far away as Sydney and SE Aust.

D.K. Raed said...

forgot to ask: is YOUR plate moving up, down, left or right? I know in coastal Calif, we were moving up (north) relative to the rest of the continent. They kept showing us future models of SF moving up where Seattle is today, and LA ending up where SF is. But I think the peninsula, Baja Calif, breaking away from central mexico & forming the Gulf of Calif (or Sea of Cortez as we called it) was the key to what is really happening with that plate. The Sea of Cortez is where the Colorado River would eventually empty if all our dams here would allow more than a few drops to reach Mexico. It is my opinion that the whole Colorado River is an old fault line, too. Scary, because that water is our major source of life here in the arid SW.

Cart said...

DK, sorry I’m a bit slow at the moment. I just reinstalled my OS and have been busy setting it up.
The Australian plate is massive, and no part of the country is near the edges. It is drifting north, and is in fact responsible for the creation of the Himalayas. One consequence seems to be the pressure on the China plate further north, hence the recent quake.
With the Australia/India plate also breaking up there is also pressure on the Arabian and African plates. While the African plate is slowly closing up the Mediterranean, there is possibly a new sea being formed along the Great Rift fault through Arabia and Northern Africa. That accounts for recent Iranian quakes.
I expect you are right about the Colorado River, the good news is that we won’t be around for any of the predicted outcomes. I’m not so sure about SF drifting that far North, though that plate is sliding North. The Juan de Fuca plate would at least get Seattle out of the way, in fact it would force Seattle down under the Rockies as that is a subduction zone. Frankly I’d prefer the Cal sliding plate zone.