Originally posted by qmantoo
Thank you for your private message reply.
I have read the thread - every page and every post. I know the thread was speculating on the small quakes just off shore. However as I said, you have
not answered my question about the reliability of the data.
Wow, you just don't give up, do you. Kinda like me. You know, I like that!
Your graphs are plots of ESTIMATED hypocenter depths. But they are the best estimates we have. In some cases they are going to be off somewhat. And in
others they are going to be off by a LOT. I have merely pointed out that where they are more likely to be off is for those quakes farther out to sea,
and of smaller magnitudes. The s-waves of the smaller ones are tougher to spot, so they have to review them more carefully, so they can define P-S
ratios and come up with a distance to the land station.
There's not a single measure of an earthquake event, that is 100% accurate. They are best estimates, supported by a backing of collaborative sciences,
and to varying degrees, supported as well by consensus and experience. And so what I am trying to tell you is that you are asking a question that is
truly impossible to answer. Unless of course you'd care to invent a way you can stick your head down into the earth and tell us what's going on!
How reliable is the data on your charts? As reliable as it can be given the circumstances. And the more you understand the circumstances of what
seismologists do, and especially in that bad spot, the better the understanding you will have of which of those depths plotted are going to be the
more accurate ones. Ones out at sea? Less accurate than those constrained over land. So look back at your plots, and basically all the ones on the
left of the first plot are not going to be as accurate, in depth, hypocenter, and epicenter, as the ones on the right. And the reason for that is the
ones off shore are only measured from the right side, if you see what I am saying.
When you put this in the context of seismic institutions and universities, which you have, and then try to use that as a point to still not understand
my explanations- keep in mind that seismologists at these places are of course aware of this problem and yet still do the best they can with what they
have to give the best figure they can under the circumstances.
A depth plot of earthquakes off the coast of Oregon and California should immediately therefore key those cautions in the people that know these
things. That's why I was the bearer of bad news in your case. Because part of the data is indeed unreliable, and in the case of depths out at sea,
particularly so. Yeah, the OBS data could make a helpful difference, so that the next time we look at your plots, all those off shore depths would be
Ha. And I am talking about offshore quakes! As if there were some kind of sureness of the depths under land! Have you looked at the uncertainty
errors for each of those quakes you have plotted? We are talking about KILOMETERS of uncertainty in depth, and in epicenter, even for those!
So now go back and look at your plots. And tell me what it really means. Any one of those dots represents only an estimated location that is really,
pretty far off. Yup, welcome to hell.
edit on Fri Mar 2nd 2012 by TrueAmerican because: (no reason given)