It looks like you're using an Ad Blocker.

Please white-list or disable AboveTopSecret.com in your ad-blocking tool.

Thank you.

 

Some features of ATS will be disabled while you continue to use an ad-blocker.

 

Quake Watch 2011

page: 195
203
<< 192  193  194    196  197  198 >>

log in

join
share:

posted on Aug, 19 2011 @ 03:34 PM
link   
Here's Susan being super.

www.youtube.com...




posted on Aug, 19 2011 @ 03:46 PM
link   
reply to post by Robin Marks
 


so,,, your saying,, no one on the Board,,watched the video?

Well done Susan,,
ya should have included puppies!
lol



posted on Aug, 19 2011 @ 03:48 PM
link   
reply to post by muzzy
 


Honshu 394 stations (USGS), Fiji 495 stations (USGS), and JMO had something like 1000 stations listed on the page so not sure where your figures came from.

Definitely the depth making the difference.



posted on Aug, 19 2011 @ 04:43 PM
link   
reply to post by TrueAmerican
 



And OH> btw muzzy, I saw that Fiji quake come in on GEE. No way that was 6+. 5.7 tops.


Methinks you do not account for depth.

I think that was 6.2. The deep Fiji quakes do not show so much on the seismos.

Don't suppose you remember the 3rd April this year? No, thought not. There was a mag 6.4 in Fiji a bit deeper so the extra depth should compensate for the larger magnitude.


Date/Time UTC,Latitude,Longitude,Magnitude,Depth(Km),Location
2011-04-03 14:07:09, -17.649, -178.577, 6.4, 551.9, Fiji Region




You have to admit that the LISS page for that day looks very similar to today no?



ETA: Just as a comparison here is the 6.7 in Fiji at 619 km deep on 29th July



Considering that is 5.6 times stronger than the 6.2 it really is not showing much.


edit on 19/8/2011 by PuterMan because: (no reason given)



posted on Aug, 19 2011 @ 04:53 PM
link   
reply to post by PuterMan
 


Ahh, but you see- I saw the quake live on II.MSVF, the station in FIJI itself. Your little server listing there does not include it. So I got a pretty clear picture of it, and was only amplitude of about 150 microns/s- maybe 200- if I remember right.

But also it was the decay of the waveform, and I also watched its propagation. Depth could play a part, yes. It was very deep. But I am sticking to my guns on it. Ok, 5.8, happy?


ETA: here, I dug up the waveform in GEE, and they have it as a 5.6:



As noted before, amplitude around 190 microns/sec. Guess the ole memory ain't too bad after all.


That's why I was surprised to see the revision up to 6.2, and I just shook my head when I saw it. Wouldn't be the first time.
edit on Fri Aug 19th 2011 by TrueAmerican because: (no reason given)



posted on Aug, 19 2011 @ 06:23 PM
link   
reply to post by TrueAmerican
 


Actually no, not happy.

Here is the 6.2 in Japan on the BHZ channel of II.ERM which is 360 miles from the epicentre of the quake. Overall it is similar, but a bit more drawn out than the Fiji one.

ERM.II.00.BHZ.2011.229

Here is the 6.2 in Fiji today on the BHZ channel of II.MSVF which is 340 miles from the epicentre of the quake. I have adjusted the scale of both of these to be exactly the same for reasons which will become apparent.

MSVF.II.00.BHZ.2011.231

So we have two quakes at very different depths but the same magnitude showing about the same, although the pattern of the waves are different quite substantially.

Now take a look at these two traces from the Vase files I just downloaded. The top one is Japan and shows larger but the reason for this should become apparent when you look at the lower Fiji trace. Because this is a normalised trace the large spike on the Fiji quake has reduced the bulk of the signal much more.



This is exactly what happens in GEE. The plot automatically compensates for the maximum count. You must have seen it so many times you probably ignore it.

I rest my case.

reply to post by TrueAmerican
 


Ok good. So glad you posted that. It just proves my point. Look at the huge spike.

By the way it has not been revised in the public listings that I am aware. I have no revisions for it.


edit on 19/8/2011 by PuterMan because: (no reason given)


ETA: Oh and by the way here is the Japan 6.2 in GEE - also about 190 microns/sec



Your move - but I do believe that is checkmate.


edit on 19/8/2011 by PuterMan because: (no reason given)



posted on Aug, 19 2011 @ 06:51 PM
link   
reply to post by PuterMan
 


fromhere

I wondered about that too, its a long list

maybe they only got 1 direct mb reading and 2 ML or they just haven't changed the top of the text.

where does it say 495 stations? or did you add them up?
edit on 19-8-2011 by muzzy because: (no reason given)



posted on Aug, 19 2011 @ 06:58 PM
link   
reply to post by muzzy
 


It come from the 7 days text file. It is one of the fields.

I did add the Japan one up though.



posted on Aug, 19 2011 @ 07:36 PM
link   
reply to post by PuterMan
 


Checkmate?
I had no idea we were playing seismic chess.

:shk:

First of all, the FIJI quake most certainly WAS revised on USGS. One look at the phase data, and you should have seen that.

neic.usgs.gov...

They listed it as a 5.6. And I happened to be in full GEE monitoring mode and on ATS at the time, so I checked to see what it was. 5.6 sounded reasonable, as my guess on it was 5.5. But you know I don't bother much with small quakes like that anymore, so I just let it be. The revision came later, just before the 6.3 hit in Japan I think, because I was literally sitting here with that feeling "I know this isn't right" nagging me when I saw the revision to 6.2 on the FIJI quake. And before I could really say or do anything, the "6.8-JMA" hit in Japan, taking my attention away.

Second, there is no use in comparing different quakes relative to this discussion of the FIJI quake alone. That's like comparing apples to...to...dinosaurs. Look at the phase data again and average those magnitudes from the stations. Without that one 6.8 figure at RAR, a station in the Cook Islands so prone to problems to the point I won't even open it anymore, you have no chance of getting 6.2. I trust what I know through experience more than I do that crappy station to include it in averages. And by the time you're out 500 miles or more from epicenter, I don't even want to know. Don't care. I use the closest stations. And note which is the first station listed in the USGS phase data as closest: II.MSVF- the station I saw it on live.

And FYI, that max amplitude (negative) in your GEE post there was -212 or so, not 190. It simply represents a negative peak ground velocity- but don't forget to look both above and below for the maximum displacement.

I am still sticking to my guns. That was no 6.2, no way in hell.



posted on Aug, 19 2011 @ 08:02 PM
link   
reply to post by TrueAmerican
 


I will grant you that it may have been put out as a 5.6, only problem now it is you who is not comparing like to like!


If you look at the figures the data is thus:


Date/Time UTC,Latitude,Longitude,Magnitude,Depth(Km),Location
2011-08-19 03:54:27, -16.525, -176.905, 6.2, 413.2, Fiji Region
2011-08-19 03:54:27, -16.520, -176.970, 5.6, 412.0, Fiji Region


Top is USGS and bottom is EMSC

(Sorry forgot to add the EMSC link)
www.emsc-csem.org...



So you see your 5.6 is the mb value however Mt is teleseismic moment, also called Mw - so you are not comparing like for like.

earthquake.usgs.gov...

If you look at the Japan quake that is also Mw

earthquake.usgs.gov...

So not only am I comparing like for like, unlike you, but I also stand by what I said that it was NOT revised since issued or it would have turned up in the revisions in my database. By the way the phase data for the Japan quake shows 5.8 mb.

Negative, positive? No difference as the waveform is centred. It does not make any difference which direction the max peak is. For instance if you are looking at a different channel it only means the greater direction, i.e. a greater negative east channel is more movement in a westerly direction.

ETA: Obviously we should both state our scales before opening mouths!!



edit on 19/8/2011 by PuterMan because: (no reason given)



you have no chance of getting 6.2


Nor would I expect to since, as I observed on this thread a couple of days ago, those values are mb.

Just in case you did not actually average the figures the value is 5.538735


edit on 19/8/2011 by PuterMan because: (no reason given)



posted on Aug, 19 2011 @ 09:04 PM
link   
Puterman, are you trying to make THIS the longest page evar. That one post makes my finger have to spin that wheely thingy real fast.

I'm not getting into the debate. But I do remember when I saw it showing up on the graphs I monitor, and when I cross referenced to find out where it had come from, I was confused because it looked like two quakes to me. Don't ask me to explain. Not gunna.

You are making me think about Figi. And you know I usually don't comment on the big ones. I obsess about the little ones. The microsiesm noise. But someone asked me in a email about Figi since they were going to move there. I watch all the quakes worldwide and watch their patterns, but I don't analyse each and every fault system. I just knew it to be in the Ring of Fire and since it is a brand new volcanic creation, it is siemically active and there is a risk. I just advised the usually prepardness stuff, looked at the risk and historic map, and thought that there wasn't a significant threat. Then this 5-6+ M quake has gotten me wondering if there might be something brewing. Since they are an ATS reader, any thoughts on Figi and what's what would be appreciated.

When I see a quake in Figi, or anywhere else in that area, I just watch the other faults and see if it fits with a consistent pattern. I am more interested in the odd quakes. The ones that don't fit, or the ones that show a pattern. Also, if an area is unrepresented, then the stress is building, so an earthquake becomes more likely. Like South America. I think it's overdue. I really think plate tetonics is at work. Puterman is right to point out that many strange things are happening to different zones, that don't fit the model exactly. But that's nature. There is an overall pattern. Yet, in each case there is always the unique element, and the mutation. I just picked a fava bean today that look like a pregant woman's torso. Anyway, It's ugly, but I think there is a discernable pattern. Just like the moon. There is a pattern. It's just that it's always unique, and so you need massive data and statistical math to find it's small influence. I was watching Shelock Holmes today. Someone threatened his brother by saying his pistol had a hair trigger. That's sometimes all it takes. A nudge is all.

Here's a quake that will stick in my head for no other reason than it's not regular.

earthquake.usgs.gov...


edit on 19-8-2011 by Robin Marks because: (no reason given)



posted on Aug, 19 2011 @ 09:26 PM
link   
reply to post by Robin Marks
 


In the last 365 days 9 x 6+


Date/Time UTC,Latitude,Longitude,Magnitude,Depth(Km),Location
2011-08-19 03:54:27, -16.525, -176.905, 6.2, 413.2, Fiji Region
2011-07-29 07:42:23, -23.650, 179.821, 6.7, 521.7, South Of The Fiji Isls.
2011-07-22 06:56:40, -20.228, -178.529, 6.0, 600.6, Fiji Region
2011-04-03 14:07:09, -17.649, -178.577, 6.4, 551.9, Fiji Region
2011-03-31 00:11:59, -16.566, -177.492, 6.4, 23.7, Fiji Region
2011-02-21 10:57:53, -26.083, 178.439, 6.4, 561.8, South Of The Fiji Isls.
2010-12-28 08:34:17, -23.374, -179.793, 6.3, 551.6, South Of The Fiji Isls.
2010-12-01 16:01:27, -15.904, -178.947, 6.1, 15.2, Fiji Region
2010-09-07 16:13:32, -15.869, -179.261, 6.3, 10.0, Fiji Region


There were 85 of 5+

Many quakes in Fiji are deep. Oh I was not going to show the 5+ but here you go in depth order deepest first.


Date/Time UTC,Latitude,Longitude,Magnitude,Depth(Km),Location
2010-12-15 12:03:33, -26.794, 178.759, 5.0, 656.0, South Of The Fiji Isls.
2011-02-24 18:32:00, -18.072, -178.418, 5.4, 618.8, Fiji Region
2011-04-27 23:35:09, -17.851, -178.535, 5.1, 608.9, Fiji Region
2011-07-22 06:56:40, -20.228, -178.529, 6.0, 600.6, Fiji Region
2011-08-03 04:51:42, -18.634, -176.102, 5.0, 597.5, Fiji Region
2010-12-11 13:43:19, -21.774, -179.081, 5.6, 594.3, Fiji Region
2011-07-19 18:20:31, -25.114, 178.530, 5.0, 588.2, South Of The Fiji Isls.
2010-10-30 07:07:20, -20.858, -178.513, 5.0, 584.7, Fiji Region
2011-05-04 16:13:28, -20.384, -178.556, 5.6, 583.9, Fiji Region
2011-03-23 14:14:40, -20.823, -178.730, 5.1, 576.5, Fiji Region
2010-11-30 05:17:06, -21.157, -178.950, 5.1, 574.3, Fiji Region
2011-05-12 12:29:23, -19.754, -177.785, 5.1, 573.8, Fiji Region
2011-08-09 11:11:23, -20.551, -178.395, 5.3, 565.6, Fiji Region
2011-04-05 04:10:08, -17.632, -178.524, 5.7, 565.5, Fiji Region
2011-01-28 12:37:18, -21.323, -178.686, 5.2, 563.7, Fiji Region
2011-06-13 12:46:00, -19.186, -177.490, 5.4, 563.5, Fiji Region
2011-02-21 10:57:53, -26.083, 178.439, 6.4, 561.8, South Of The Fiji Isls.
2011-07-07 19:08:36, -17.820, -178.622, 5.6, 561.3, Fiji Region
2010-12-10 09:23:09, -20.251, -177.924, 5.1, 559.2, Fiji Region
2011-06-22 22:16:56, -21.744, -179.067, 5.2, 554.3, Fiji Region
2011-07-19 07:15:54, -23.559, 179.125, 5.2, 552.2, South Of The Fiji Isls.
2011-07-29 07:50:57, -23.642, 179.721, 5.2, 552.1, South Of The Fiji Isls.
2011-04-03 14:07:09, -17.649, -178.577, 6.4, 551.9, Fiji Region
2010-12-28 08:34:17, -23.374, -179.793, 6.3, 551.6, South Of The Fiji Isls.
2011-01-13 10:41:42, -22.232, -179.198, 5.0, 551.0, South Of The Fiji Isls.
2010-12-12 09:40:11, -23.960, 179.488, 5.0, 550.9, South Of The Fiji Isls.
2011-06-25 21:16:57, -24.408, 179.507, 5.7, 546.9, South Of The Fiji Isls.
2010-11-28 16:47:38, -24.126, 179.097, 5.1, 546.3, South Of The Fiji Isls.
2011-04-11 02:01:20, -17.766, -178.529, 5.2, 538.8, Fiji Region
2011-07-29 08:19:09, -23.398, -179.886, 5.1, 538.5, South Of The Fiji Isls.
2011-08-02 19:18:48, -23.899, 179.098, 5.8, 538.2, South Of The Fiji Isls.
2011-05-08 00:09:16, -20.092, -178.157, 5.0, 534.9, Fiji Region
2011-01-24 08:37:45, -23.449, -179.763, 5.0, 534.1, South Of The Fiji Isls.
2010-11-24 18:35:53, -24.348, -179.617, 5.1, 530.4, South Of The Fiji Isls.
2011-03-27 10:59:26, -24.021, 179.943, 5.0, 530.1, South Of The Fiji Isls.
2010-12-02 02:29:17, -20.267, -177.819, 5.0, 528.7, Fiji Region
2011-02-16 15:56:00, -20.177, -177.610, 5.0, 528.5, Fiji Region
2010-12-29 23:27:01, -23.084, -179.916, 5.2, 528.4, South Of The Fiji Isls.
2010-10-31 09:58:07, -23.797, -179.580, 5.1, 524.8, South Of The Fiji Isls.
2010-09-18 14:29:14, -17.330, -178.850, 5.0, 524.0, Fiji Region
2010-09-05 23:48:26, -23.735, -179.999, 5.4, 523.6, South Of The Fiji Isls.
2011-04-10 16:18:18, -23.611, 179.821, 5.0, 523.1, South Of The Fiji Isls.
2011-07-29 07:42:23, -23.650, 179.821, 6.7, 521.7, South Of The Fiji Isls.
2011-07-08 23:31:24, -17.484, -179.051, 5.1, 520.7, Fiji Region
2011-03-20 19:46:56, -25.092, 179.541, 5.0, 513.1, South Of The Fiji Isls.
2011-02-02 16:38:10, -24.750, 179.985, 5.2, 513.1, South Of The Fiji Isls.
2011-08-11 01:13:43, -24.698, 179.940, 5.1, 511.4, South Of The Fiji Isls.
2010-10-30 10:39:24, -24.874, 179.574, 5.2, 501.9, South Of The Fiji Isls.
2010-10-05 03:36:48, -20.763, -177.740, 5.1, 477.3, Fiji Region
2010-10-16 03:24:00, -24.775, -179.617, 5.0, 474.5, South Of The Fiji Isls.
2011-04-02 18:50:19, -24.317, -179.824, 5.1, 445.1, South Of The Fiji Isls.
2011-08-19 03:54:27, -16.525, -176.905, 6.2, 413.2, Fiji Region
2011-04-19 15:30:09, -20.003, -177.687, 5.0, 405.9, Fiji Region
2011-07-23 04:40:20, -24.219, -178.841, 5.2, 366.0, South Of The Fiji Isls.
2011-03-16 00:10:09, -21.216, -176.699, 5.1, 268.3, Fiji Region
2011-08-12 03:15:12, -21.704, -177.104, 5.6, 243.0, Fiji Region
2011-03-12 08:38:39, -20.310, -176.185, 5.0, 229.3, Fiji Region
2011-02-13 19:05:55, -20.853, -176.637, 5.1, 206.4, Fiji Region
2011-01-23 19:15:39, -20.322, -176.228, 5.8, 202.3, Fiji Region
2011-01-10 02:11:04, -19.466, -176.025, 5.3, 175.9, Fiji Region
2010-10-21 07:25:44, -25.732, -177.571, 5.0, 160.4, South Of The Fiji Isls.
2010-12-08 14:41:24, -22.469, -176.018, 5.2, 145.8, South Of The Fiji Isls.
2011-05-05 16:15:20, -25.046, -177.437, 5.4, 131.9, South Of The Fiji Isls.
2011-01-07 15:46:48, -25.098, -177.669, 5.2, 116.0, South Of The Fiji Isls.
2010-12-27 06:41:48, -22.937, -176.381, 5.2, 105.7, South Of The Fiji Isls.
2011-06-30 14:16:20, -23.345, -176.131, 5.0, 52.8, South Of The Fiji Isls.
2010-12-11 17:13:35, -25.403, -176.348, 5.0, 44.3, South Of The Fiji Isls.
2011-08-07 07:01:47, -20.132, 179.725, 5.4, 41.7, South Of The Fiji Isls.
2010-09-07 12:49:01, -14.360, -176.240, 5.4, 35.5, Fiji Region
2011-08-12 23:43:34, -24.327, -176.592, 5.0, 34.6, South Of The Fiji Isls.
2011-04-21 22:31:20, -26.785, -176.105, 5.1, 34.2, South Of The Fiji Isls.
2011-06-28 07:07:21, -16.680, -177.344, 5.0, 29.6, Fiji Region
2011-03-31 00:11:59, -16.566, -177.492, 6.4, 23.7, Fiji Region
2011-08-03 03:20:21, -16.685, -177.189, 5.1, 19.1, Fiji Region
2010-12-01 16:01:27, -15.904, -178.947, 6.1, 15.2, Fiji Region
2011-03-26 22:49:42, -15.788, -179.493, 5.9, 13.4, Fiji Region
2011-07-06 14:46:37, -16.482, -177.506, 5.0, 10.0, Fiji Region
2011-06-19 21:26:42, -15.058, -178.028, 5.1, 10.0, Fiji Region
2011-06-05 16:55:50, -14.983, -177.860, 5.1, 10.0, Fiji Region
2011-06-05 16:35:03, -15.079, -177.934, 5.8, 10.0, Fiji Region
2011-02-03 11:13:48, -18.529, -176.289, 5.0, 10.0, Fiji Region
2010-09-07 16:13:32, -15.869, -179.261, 6.3, 10.0, Fiji Region
2011-07-05 19:02:37, -14.689, -176.152, 5.3, 7.9, Fiji Region
2011-03-31 02:59:17, -16.276, -177.622, 5.4, 4.9, Fiji Region
2011-07-10 18:47:13, -15.513, -176.071, 5.3, 1.3, Fiji Region




All in the last 365 days by the way

You might find this of interest but i think their statement of a mag 6 every three years is a bit suspect!!

CHIHUAHUA: Yes unusual. There was a 3.1 in 2007.



posted on Aug, 19 2011 @ 10:41 PM
link   
reply to post by PuterMan
 


Actually, I forgot- been away for a while, but the amplitude= the sum of the scale extremes divided by 2, to take in to account off centering (drift) of the scales. MSVF is currently about +8 microns/sec off center. You can see it in the screenshot, and I see it now in GEE.



posted on Aug, 19 2011 @ 11:33 PM
link   
Earlier I stated that I thought wave action from the ocean impacted faults far inland. It dawned on me after I mentioned that the Chihuahua quake was irregular, that it may in fact be an example of this wave effect.

What do we have off the coast of Mexico?
A hurricane.
And there are tropical waves hitting the other side of the continent off Florida.
So, you have waves hitting the continent from opposite sides. This small, but measurable movement must be interacting inland. The microsiesmic waves would be passing through each other as they travel in opposite directions. As if you were to drop two stones in the water. The waves from each would travel uniformly until the met the waves from the other.

I believe these colliding waves caused the Chihuahua quake.



posted on Aug, 19 2011 @ 11:50 PM
link   
Depth at Source and Distance from the recording station are the other prime factors when looking at the size of the traces on LISS, as well as magnitude.

Just in time I caught this Tonga 5.2 while the Fiji and Japan quake were still on SNZO
here is what usgs have determined as a 5.2mb, just 0.4 smaller than the Fiji one but twice the size on the graph because
1. it was shallower
2. it was closer to SNZO

(I've put the original graph from this morning on top so its easier to compare)


It has also been my observation that location on the Tectonic Plate plays a part too.
Often the closest station to the epicentre does not necessarily show the biggest trace, in this case the Fiji quake is deep in the interior of the corner of the Australian Plate under the Lau Basin, so the S and P waves have more rock to travel through to SNZO whereas the Tonga quake is right on the edge of the Australian Plate and the shock waves can easily travel down the Plate interface ( Tonga/Kermadec/ Hikurangi trenches) to Wellington (SNZO).
I have seen this many times with quakes in the N and NE of NZ area where you would think closer station like URZ on the East Cape or HIZ in the Waikato (on IRIS) would show the biggest trace, but it wasn't the case at all, SNZO showed bigger. (because of the trenches?).
ML was a pretty useless measurement on these 3 quakes all the same but look at the different sizes on the graph, even taking distance forom SNZO into account.
edit on 20-8-2011 by muzzy because: (no reason given)


FWIW I'm actaually starting to like the way the Russians do the Global quakes better than USGS, they are always in mb, with the odd one converted to Ms as well.
At least there is no fiddling around with mysterious magnitude types like UCMT
RAS had Japan at 6.5mb and 6.3Ms and Fiji (they call it W of Tonga) at 5.7mb
www.ceme.gsras.ru...

and Tonga at 5.5mb
www.ceme.gsras.ru...

they can be a bit slow posting up their guesses though.

As a 3rd cross reference AuGeo had them at 6.2, 6.2, 5.7 respectively.
www.ga.gov.au...

edit on 20-8-2011 by muzzy because: (no reason given)



posted on Aug, 20 2011 @ 12:45 AM
link   
Haven't felt one here for a while, just a slight wobble, thought I was imagining things.
I had the time at 3:32pm NZST so it is possible there was another one I felt, that hasn't been posted on Recent Quakes

Reference Number 3565359 [View event in Google Maps] [View Felt Reports in Google Maps]
Universal Time August 20 2011 at 2:45
NZ Standard Time Saturday, August 20 2011 at 2:45 pm
Latitude, Longitude 41.25°S, 174.69°E
Focal Depth 40 km
Richter magnitude 3.2
Region Wellington
Location
Makara 10 km north-west of Wellington

www.geonet.org.nz...

edit on 20-8-2011 by muzzy because: (no reason given)

I filled out a Felt Report anyway, making a note of the time discrepency, but looks like they put me on the map for this one anyway, Raumati Beach = MM3


edit on 20-8-2011 by muzzy because: (no reason given)


Heres my quake on SNZO.IU.00.BHZ
www.iris.edu...
edit on 20-8-2011 by muzzy because: (no reason given)



posted on Aug, 20 2011 @ 04:50 AM
link   
reply to post by muzzy
 


I think I am slowly getting my head round that way USGS do things, although as I have noted it does not seem to be consistent.

May I refer you to that PDF document on scale comparisons again, figure 4b. (By the way looking round on the web this document seems to be the bible of conversion)

The problem with mb is that it is only good to the mid 6 level very similar to ML.



Mw is just a representation of the dynes centimetres of energy. (Why is it I always end up typing that work value in the morning before work should even be considered. Not even finished the first coffee. Sad really - ATS comes first)

As such it is in many way a more accurate representation of the quake in my opinion. Ms is very similar, but all the others fall short in some way. So yes you can use mb for some - the average larger quake in the 6 range but if becomes less accurate over the 7 mark.

Bear in mind that mb ans ms/mw measure different things. Mb is moment of body magnitude and is the scale developed to measure deep focus earthquakes, and equates to ML hence the similar cut off point of accuracy. It measures the P wave. Ms is the surface wave magnitude and Mw is moment magnitude which are not quite the same thing in terms of measurement but approximate best.

Also remember that Ms, since it measures the surface wave, may be determined considerably later than Mb.

Here is another useful PDF which I have added to my Mw conversion page

More 'stuff'

Magnitude, Energy and Frequency of Occurrence A description of the Richter scale.


Moment magnitude has many advantages over other magnitude scales. First, because it uses the complete seismogram, it doesn't saturate, allowing us to measure the largest earthquakes. Second, because it can be determined either instrumentally or from geology, we can use it to measure the size of old earthquakes and compare them to instrumentally recorded events. Third, estimates tend to be more reliable so differences of 0.2 in moment magnitude do mean something (just don’t compare with some other type of magnitude.)


www.arizonaenergy.org...


"This size-of-the-earthquake problem will never go away,'' said Tom Heaton, a seismologist at the California Institute of Technology in Pasadena, who has been embroiled for years in the magnitude debate.


A good straight forward description of the problem!

A good but technical document from the University of Tehran - Relation between Seismic Moment M0 and Surface Wave Magnitude Ms

This may confuse the issue as it introduces Ms Prague and MtS - further variations on a theme! OMG I just read it - think I need a sedative. I think that is enough!!! I have to have a break from magnitudes.

PS The person who wrote the first PDF - the comparison - is Kanamori, the inventor of the Mw scale.



posted on Aug, 20 2011 @ 05:13 AM
link   
reply to post by muzzy
 


SNZO to Tonga epicentre 1420 miles. 34 km deep so hypocentre not much different.
SNZO to Fiji epicentre 1769 and with such a deep quake further to the hypocentre. 1817 I make it.
SNZO to Japan 5240 miles - hypocentre not different over that distance.

Richter being designed for 600km to the hypocentre would, as you correctly state, be completely useless as a measure from SNZO.



posted on Aug, 20 2011 @ 11:38 AM
link   
reply to myself to thepost by me
 


Wow, Gutenberg and Richter's 2nd paper (PDF) Earthquake Magnitude, Energy, Intensity and Acceleration

The last sentence is:


The authors are indebted to Dr. H. Benioff for much helpful discussion


I am sure I don't need to tell you who he was! You might find this artlicle from 1950 interesting. He did not actually 'invent' subduction until someone else pointed it out to him.


In 1904, says Dr. Benioff, there was a great burst of earthquakes that lasted three years.* This period produced a tall jog on Dr. Benioff's chart. Since then the jogs have been smaller.


Little did he know that Chile was almost upon us. This is the cycle appearing.

Here is another 1950 paper which shock horror has Dr Benioff suggesting interaction with the Sun and Moon.


edit on 20/8/2011 by PuterMan because: (no reason given)



posted on Aug, 20 2011 @ 12:12 PM
link   
7.5 Mw - VANUATU
Preliminary Earthquake Report Magnitude 7.5 Mw
Date-Time

20 Aug 2011 16:55:02 UTC
21 Aug 2011 03:55:02 near epicenter
20 Aug 2011 08:55:02 standard time in your timezone

Location 18.259S 168.068E
Depth 40 km
Distances

62 km (38 miles) SSW (203 degrees) of PORT-VILA, Vanuatu
190 km (118 miles) NW (318 degrees) of Isangel, Vanuatu
319 km (198 miles) SSE (162 degrees) of Santo (Luganville), Vanuatu
1852 km (1151 miles) ENE (59 degrees) of Brisbane, Australia

Location Uncertainty Horizontal: 14.7 km; Vertical 6.8 km
Parameters Nph = 65; Dmin = 455.3 km; Rmss = 1.29 seconds; Gp = 32°
M-type = Mw; Version = 8
Event ID US c0005h9f ***This event supersedes event AT00lq8kbt.



new topics

top topics



 
203
<< 192  193  194    196  197  198 >>

log in

join