Offtopic (earthquakes, not taxonomy)
kinman2 at YAHOO.COM
Sat Jan 1 12:56:46 CST 2005
Thanks to Geoff and others who e-mailed me on this subject. The boundary between the Indian and Australian plates (just discovered in the 1990's) is clearly very close to the epicenter. Extend this boundary underneath the Burma microplate and it looks like it would run almost directly through the epicenter. I wouldn't be surprised if this southern tip of the Burma microplate is breaking off, since this is where it meets three more massive plates (Indian, Australian, and the Sunda plate as well).
Although the Macquarie quake was way over on the other side of the Australian plate, one could almost envisage a possible connection. If unusually massive forces were recently pushing the Australian plate northeasternward (even more strongly than usual), the Macquarie earthquake could have been the first release of energy, and that collision could then in turn have further concentrated the forces almost directly northward into the weak point where that plate jams up into this area where it meets the Indian, Burma, and Sunda plates. Since the Burma microplate is relatively small, it got the worst of it. In any case, the proximity of the Australian plate to the epicenter makes me think it could easily have played a causal role, even if the timing of the Macquarie quake was an independent coincidence.
However, if there is a connection, and the Australian plate still has even more damage to do in the short term, what other weak points might it affect other than the Burma microplate? If I lived anywhere close to the Australian plate from New Zealand to New Guinea, I would still be pretty nervous that more strong earthquakes (7.0-8.5) could occur within the next month or so. Not that I really know much about geology, but just a gut feeling. I think I much prefer living in Tornado Alley to being near the Ring of Fire. I'd move to Yellowstone before I would to California, and I have no desire to even visit places like Indonesia, Japan, or Alaska.
USGS quote (from Geoff's posting):
Answer: The occurrence of two great earthquakes within such a short space of time is indeed striking. However, even in retrospect, we do not yet see evidence for a strong causal relationship between the two earthquakes. [...]The Macquarie Ridge earthquake was very far from the site of the yet-to-occur Sumatra-Andaman Islands earthquake, and occurred on a different plate boundary. The hypothesis that long-term stress changes associated with the Macquarie Ridge earthquake triggered the Sumatra-Andaman Islands earthquake therefore does not seem compelling.
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