Peru-Chile Could Experience Megathrust Quake as Six Quakes Over 6 Mag Strike Area

reply to post by TrueAmerican


Where do you look to see it?

Evltre
reply to post by TrueAmerican

 

Where do you look to see it?

Well you can see almost what I just saw here:
www.iris.edu...

Except in spectro that lit my screen up in solid red. Darnit.... Fortunately through experience I know to check other stations.

Yup...verified...all channels at NNA fried. Great. Now we can't see Peru.

Another 5.7 aftershock, followed immediately by two smaller quakes:
www.emsc-csem.org...

That fault isn't done yet.

reply to post by TrueAmerican


And after that, now another what appears to be an identical 5.7 or so is incoming. Same register of counts. Hmm... Watchout down there...

EDIT: USGS has that first one at 5.5, so the following ones will be about 4.8, then another 5.4 or so, my guess- all happening within minutes of each other.


Hmm, EMSC has that second bigger one at 5.8. But that's sure to change once USGS posts.


USGS: 5.5, then 5.2, then 5.5- EMSC now after revision: 5.5, 5.0, 5.3

True American, this swarm doesn't seem to want to stop. What are your projections on where this swarm leads? Will it eventually die down and return to normal? Or are all these just foreshocks leading to a quake 8.0 Magnitude or above on the moment magnitude scale(Mw)?

Boy they sure fixed station NNA in a hurry. That usually takes days or weeks, or even months.

You're asking me about projections... Well... Maybe we should be asking scientists why they fixed that station so damn fast. Maybe they have some unspoken projections of their own. They're clearly wanting to see Peru too, obviously. Wonder why?

I have no projections, per se. We know that fault can produce mega quakes. All I am saying with this thread is that the potential of these being foreshocks is there, for sure- at least from the information that I am seeing. If that information is inaccurate (such as the initial 6.7 actually being bigger), then my concerns may be misplaced- I don't know. Others may agree or disagree, and that's fine. I didn't come here to agree. I came here to say what I think, after watching earthquakes and studying a lot of documents for over 8 years about them. Hopefully, in the end the fault will just die down as usual, and there will be no 8+. Hopefully.

reply to post by TrueAmerican


I always have bad dreams about South America... that's part of the reason I am holding it in my hand in my avatar.

symbolic for me... and spiritual also. I hope that area will remain stable and be ok.

Well so far, most of you probably only know about these bigger quakes, but the reality is that fault has been in nearly constant motion since this started, spawning all kinds of seismicity. Here is the latest from EMSC, a pic of the activity near the 6.7:



I mean that looks like aftershock activity from a much bigger quake. Seriously wondering if they weren't mistaken on that 6.7 now.

Dunno. All I can do is watch like the rest of you.

Another one incoming..this looks a bit south of the previous quakes. Small mag 5 is my guess.

The Chileans have it south, but my magnitude guess was way too high--only 4.1 Ml.

Hora UTC 15:33:52 24/03/2014
Latitud -25.297
Longitud -70.725
Profundidad 34.7 Km
Magnitud 4.1 Ml GUC
Referencia 117 km al N de Chañaral.

linky

This quake was 10 minutes prior to this mag 5.5 .
After looking at the initial mag 6.7 and subsequent quakes, I don't see the mag 6.7 being upgraded to a 7.0. Just my $0.01


I think the current worldwide drought of mag 7+ quakes will be broken in this region.

I remembered the Santa Cruz earthquake swarm last year in early February. That area got hit by multiple 6s and in the end.....BAM! An 8.0 mag struck!

I just wanted to share an easy page to monitor activity along the entire Chilean coast.

This image shows the most recent 2 hours of activity, from north to south. You can also click the 24 hour tab, to see the past day. The page automatically updates every 4-8 minutes.
Earthscope--Chile

TrueAmerican
Well, what are you waiting for Muzzy, go find the lowest magnitude you can and add it to spreadsheet! So which agency has your particular favor today? Oh wait! Looks like USGS has the lowest magnitude today! Oh no! What are you going to do? Can't use their Mb of 6.0! Noooooooooooooo. Chile has 6.2 Mw. EMSC 6.3 Mw. Oh dear. What a terrible problem.

Not sure which event you are referring too, likely that last one on the 23rd? but I think you are speaking generally
You misunderstand what my maps and graphs represent.
All my stuff regarding this series is from the Geology Department of the University of Chile, I keep putting that in the posts
"Servicio Sismológico Universidad de Chile"
but you don't seem to see it......

If you are referring back to the 5.8ML on the 22nd then thats what it is, 5.8ML, if GUC don't convert it to Mw then it is not my place to convert it. If GCMT say its 6.3Mw then I will add that * for general information on my page.
IRIS, USGS and EMSC all have daily or 7 day interactive maps now, so what is the point copying their stuff again?, GUC don't have interactive maps, that is why I'm doing it.
If you look back on EQ Archives you will see all my big event pages, regardless of whether they are from Japan, Greece, Italy, New Zealand or Chile are all based on data from the country the earthquake is in. You may also note that all these sources still use ML, which as far as I am concerned is a default magnitude type, even if you look at old or new USA/Alaska/Hawaii USGS data most of it is in ML too. Mw conversion varies depending on siesmic region, so can't be used to compare the size of earthquakes from different regions, ML is more useful for this purpose.
We don't need some "experts" from the USA, who rarely get the initial location right to within 50km, to tell us where and how big earthquakes are. If you look back on some older events in the last 3 years you would have noted the consistent changing of data by USGS once they get a look at other Networks data, USGS are a bunch of guessers at best and pretty well useless for immediate accurate data.

I don't pick the lowest magnitude, and I don't change data sources in the middle of a series just because I don't like the numbers. I use GCMT from IRIS throughout my pages for the MT also to be consistant, as USGS chop and change whether its Mww or MWp or Mwtf depending on which area an event is in. I used GFZ for a while but I like the clean red and white image GCMT use.

FWIW here is the page I was working on, up to the 22nd UTC, I have been away out of town since 23rd, so a bit of fresh data to add in now, when I get time. offshore Tarapaca, Chile, 16/03/2014, 6.7Mw and aftershocks

TrueAmerican
reply to post by Red Cloak

 

[snip]. You have obviously not studied even one bit about seismic instruments, digitizers, and telemetry in general, to be making such ludicrous remarks. Scientific calculation based upon instrumentation is scrutinized on a daily basis by other scientific peers. And that includes quake magnitudes. [snip] Just never mind. I can see this is going to be pointless. I won't confuse you with the facts, seeing as your mind is already made up...

I don't understand why people do this. If you don't know, why don't you just admit to yourself you don't know, and go study to learn more, so that you can come to a forum like this and actually have a viable conversation? [snip]
And as to the 1960 Chile quake, it is estimated from data that about 900 to 1000 km of rupture occurred to create that quake- the most powerful quake ever recorded. So if twice that amount, or 2000 km of fault ruptured at once, then what magnitude would that be, in Mw? Of course, that would be assuming you understood seismic moment, and the various magnitude types in use today. I won't hold my breath, seeing as the answer would depend on the width of the fault rupture as much as the length. But of course you knew that, right? Of course.

UPDATE: Things seemed to have quieted down pretty well on the fault, and the aftershocks seem to be diminishing in frequency and magnitude. Let's hope it keeps that up.

edit on Tue Mar 18th 2014 by TrueAmerican because: (no reason given)

Since they removed my post for a "manners violation".............

I am a geologist and a seismologist and everything I posted is accurate. Stop trying to mislead people. [snip]

###ATTENTION###

The thread topic is speculation about an impending earthquake along the Chile-Peru Trench

Civility is expected and members must argue the points.

Any more mischief from members will not be acceptable.

Play on...

Interesting. We seem to be getting reactions now to this activity, with a 5.3 in Ecuador (north), and a 5.0 and 4.8 south of there in the mid Chile coast. Coulda sworn I mentioned that possibility somewhere... and thankfully they were small.

But hopefully these quakes will be the cutoff points, and this thing will die down for good. Been pretty quiet all night at the main location, aside from those quakes and some small quake activity. If it dies down today, we might be in the clear... Maybe...

As you folks can see, there are many different seismic agencies, and clearly, us quake watchers feel very differently about them. I can say though, if it weren't for some friends of mine at the USGS, I would not have what I do. They have treated me extremely nicely, and have bent over backwards frankly to help me. And they didn't have to. At all. Most of the information I have brought you all over the years has come from them. I can count on straight answers from them when I ask, and that's all I CAN ask from anyone. While I may not agree with the magnitudes sometimes, so what. No one agrees on much of anything around here anyways. Boo hoo. We get over it and move on.

Hmm, so now EMSC is reporting two quakes in Southern Peru, a 5.1 and a 3.2

www.emsc-csem.org...

And those ARE directly north of the massive activity, as I suspected might happen.

Interestingly, USGS doesn't show either of them yet. Maybe that's cause station II.NNA in Peru is on the fritz again. grrr... I'm getting no data from it at all. I just got a bad feeling bout this...

reply to post by TrueAmerican


USGS has the southern Peru quake as a mag 5.1 mb after revision (originally popped up as a 5.0).

The depth of 87 kms, if this is shown to be a thrust fault, means that this quake just added a little more "downward pull" on the locked portion to the west.*

I'm with you, it looks like something larger may be on the horizon.

(* according to subduction zone mechanics of plate tectonics--not everyone buys into it--but to my mind, it's the best, predictive mechanism we have to work with, currently)

Magnitude and Magnitude Type ARE important due to the amount of energy released and can alter the result when analyzing the amount of energy released, which in turn can alter the residual energy that may yet be there.
Of course no one knows what amount of built up pressure there is in the Peru-Chile Trench, all we know is that there was a 55 year gap between the last two M8's in Chile, and Peru has a shorter average gap of 33 years
I have a pdf from Centro Nacional de Datos Geofísicos - Sismología, Peru that shows 15 M8+ events since 1471 to 1982
running the figures through the average gap is calculated as follows
MAG, WHEN, GAP IN YEARS
8.0, 1471
8.7, 1513, 42
8.4, 1555, 42
8.2, 1582, 27
8.4, 1584, 2
8.1, 1600, 16
8.8, 1615, 15
8.2, 1687, 72
8.4, 1746, 59
8.2, 1821, 75
8.8, 1868, 47
8.6, 1868, 0
8.4, 1869, 1
8.6, 1950, 81
9.0, 1963, 13
AVERAGE, 33
As you can see the gaps vary widely, but the 1582/4 and 1868/9 short gap is interesting, that is a big release of energy with multiple 8's in each case, this could give some clue as to the potential energy pent up in the Peru section of the Fault.
Figures are incomplete for the whole Trench though, there two were northern section M8's in the 1970s, one off Lima in 1974 and one off Ecuador/Colombia in 1979 so the average gap is likely smaller if you stretch the list out another 32 years.