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

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.

reply to post by TrueAmerican

you didn't click on the map, its 5000km of the trench that is covered in the table, Peru and Chile.

This topic caught my attention because I had just done some research on Chile the day before the 2 x 6's.
Sorry if the facts get in the way of a good story .....

reply to post by TrueAmerican


my wife is in peru right now.
Her parrot died that night from shock..She stayed in bed because she felt that it was not a strong one..Was near lima..

reply to post by TrueAmerican


TrueAmerican, thank you for this post.. didn't know this was happening! This definitely interests me seeing that I am an Ecuadorian..

reply to post by TrueAmerican


Sorry if I missed it in the thread, but what is the depth of this one?

Even small quakes make big trouble depending on depth.


Thanks,

RT

reply to post by Rezlooper


Rezlooper good observations/news reports of the die offs.

I'd speculate we are going to see a major eruption. Think about the stories you are linking and what they describe. Now think about the stories in the Bible about Exodus and the plagues before the Exodus. (I reference this from a scientific point of view and not a religious one.)

Lots of fish and aquatic life dying off - a major eruption may be coming. Just a guess, but with that level of gas escaping from the ground it seems that the warning signs might be there. Not sure what seismologists are saying, it would be worthwhile to find seismologists that mainly study the South American regions activity.

SWCCFAN

This guy has been nearly spot on with his quake predictions.

I like the background music he puts on his videos.

Creative, smart dude

kauskau
reply to post by TrueAmerican

 

my wife is in peru right now.
Her parrot died that night from shock..She stayed in bed because she felt that it was not a strong one..Was near lima..

Sad

[snip]

There was another large quake, appears to be an aftershock of not sure which mainshock now... but depending on which agency- USGS: 5.9 EMSC: 6.0

So obviously there is still considerable stress energy being stored in the fault at that point. And just when it appeared to be dying down, bam. So that's like 5 six pointers now. I keep expecting it to just die down and dissipate. But it won't quit!

And thanks to Olivine, who reminded me in a u2u of a station I used to watch in Peru on the II network- station NNA. I had such trouble with that network I refused to even call it up anymore as of years ago, so I forgot about it. But have had it up since Oli said that, and seems to be performing a lot better. Which means if anything goes down in Peru, I will be on it.

TA, if 2000km of the fault ruptured, what magnitude in Mw would the quake be? 9.7?

reply to post by Menedes567


For Mw magnitude, it would depend on the width of the rupture, because that is calculated on the total area of rupture.

But one thing I wanted to note: in reading around more about the Great 1960 Chile Valdivia quake, there wasn't just the one 8.2 foreshock. Nope. There were apparently FOUR foreshocks, all very high in magnitude- so funny you didn't mention that muzzy- when you just finished studying it.

Now granted, that was on the southern part of the fault. Here we are talking more about the northern part. But considering it is the same general fault, I don't think it is alarmist to be cautious when we get five 6+'s within days on ANY part of that fault.

reply to post by TrueAmerican


I see, now I will try to put an example by width of movement of fault line. So, what kind of magnitude of a quake would be measured in Mw if, for example, a 2500 km fault moves by 45 meters?

Menedes567
reply to post by TrueAmerican

 

I see, now I will try to put an example by width of movement of fault line. So, what kind of magnitude of a quake would be measured in Mw if, for example, a 2500 km fault moves by 45 meters?

edit on 19-3-2014 by Menedes567 because: Adding some words........

Well, you've provided an average displacement of 45 meters, I suppose, but you would still need to provide width of rupture for calculating area, and approximate depth of hypocenter, so that shear modulus could be averaged- because shear modulus increases with depth.

Menedes567
reply to post by TrueAmerican

 

I see, now I will try to put an example by width of movement of fault line. So, what kind of magnitude of a quake would be measured in Mw if, for example, a 2500 km fault moves by 45 meters?

edit on 19-3-2014 by Menedes567 because: Adding some words........

Although I understand the concepts, and have done some pretty good reading on earthquake science, I am by no means a scientist, who can tear apart and work formulas like scientists can. But provide a scientist with the right question containing the information they need, and they are usually happy to answer. So that's exactly what I did, to get you an answer. I had to add some things, because to calculate Mw more things need to be known, or at least estimated. So here is the question I posed to one of my scientific contacts:

"Assuming a 2500 km section of fault were to rupture at once in a massive quake, and assuming a hypocentral depth of 20 km, and assuming a 200 km width of rupture with a 45 meter average displacement, and assuming a shear modulus average of 40 Gpa, what would be the corresponding Mw?"

They replied that this question was perhaps the easiest question I have ever asked them! HA! (I have been in contact with them for years.) And amongst a bunch of math and formulas, the final answer that spewed forth:

About 9.97 Mw

Yes, that would be the greatest, most destructive quake ever, and if it occurred there on the Peru-Chile trench would no doubt unleash a tsunami from hell that would affect the entire Pacific.

There were a couple of other comments, but also this:
"The scenario you describe is somewhat beyond the maximum conceivable earthquake (on this planet), but not all that much."

From other documents I have read, further fault ruptures since the big 9.5 have occurred there, but somehow they seem to get "stopped" by blockages- limiting the total fault rupture length. So in other words, it would be extremely unlikely that 2500 km of fault length would rupture at once.

I have another theory about magnitudes, foreshocks, and potentially on the long term what all these megathrust quakes could be leading up to, but I'll spare you all the gory details.

reply to post by TrueAmerican


Thanks for the scientific analysis, sir. Are you studying geology in University, TA?

TrueAmerican

But one thing I wanted to note: in reading around more about the Great 1960 Chile Valdivia quake, there wasn't just the one 8.2 foreshock. Nope. There were apparently FOUR foreshocks, all very high in magnitude- so funny you didn't mention that muzzy- when you just finished studying it.

I didn't think you wanted my opinion.....
I was looking at Chile recently, like Dec 2013-March 2014, not back in 1960.
In 1960 I have 5 foreshocks above M7, if you include Peru, maybe there were others just below that mark too, like 6.9 or 6.8, don't know, M6's are not part of the M7 project at the moment. And it depends which Networks you use, generally the data I have compiled uses the Centenial List as the default, but brings in Ms readings too if they are available, so 2 x M8 foreshocks for the Peru/Chile zone in 1960 in that case.
here is the map for 1960 M7+

Guys, we just had another 6 mag quake in the Chile area today. Check it out here >>> quakes.globalincidentmap.com...

reply to post by Menedes567

Magnitude: 6.2 (Mw)
Epicenter: 70.90°W 19.82°S
Depth: 23 km
geofon.gfz-potsdam.de...

but only 5.8ML according to the Chileans, about the same as the last big aftershock on 18/03/2014 21:26:46UTC, this one further west than the others, right on the Trench. (geofon have it further east near the others)

Hora Local 09:59:54 22/03/2014
Hora UTC 12:59:54 22/03/2014
Latitud -19.836
Longitud -71.384
Profundidad 31.8 Km
Magnitud 5.8 Ml GUC
Referencia 135 km al O de Iquique
www.sismologia.cl...

if these were low 7's instead of low 6's,then there would be cause for concern

the trend was downwards, graph at 117hrs (4.8days)

reply to post by muzzy

Thank you for adding the data about this recent event there, Muzzy. Even though virtually all of these more significant events get posted in QW I think it's good to have it in this thread as well. I especially appreciate the graph that indicates the downward trend with aftershocks.

Just for reference purposes, here's the data for this event currently shown by EMSC:

Magnitude Mw 6.3
Region OFFSHORE TARAPACA, CHILE
Date time 2014-03-22 12:59:57.0 UTC
Location 19.73 S ; 70.92 W
Depth 5 km
Distances 462 km SW of La Paz, Bolivia / pop: 812,799 / local time: 08:59:57.0 2014-03-22
98 km NW of Iquique, Chile / pop: 227,499 / local time: 08:59:57.0 2014-03-22

Slightly different lat and long coordinates, but that's not a big issue. As for the magnitude they're only showing it as 0.1 bigger than what USGS has posted on their data page, but that's also not a major concern. These variations are pretty typical, as you know.

The only thing that puzzles me is the depth. EMSC has it as 5km, USGS says 15.2 km, Geofon says 23 km, and the Chilean site says 31.8 km. That's quite a range and seeing as depth is useful to know I'm wondering who's the closest. What's your take on it? Who tends to be most reliable in that regard? (If it's possible to determine at all, naturally.)