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

Still waking up here......so has this 7.8 happened on land or out at sea? I'm confused....
BUT it seems you guys in the know are in agreement that this has 'broken the mould' and we are looking at the start of something new, yes?

Rainbows
Jane

reply to post by muzzy


In examining the waveform from the BHZ channel of LVC.IU for the 7.6, I can see how the seismologists interpreted the S&P differential differently, to cause the disparity in epicenter locations between the three agencies. And I found the problem. The USGS picked a closer flag to the end of the P-wave for the S-wave arrival than did Chile or EMSC, and looking at it further, I can see exactly what happened. The difference between the flag picks for S-wave arrivals works out to almost exactly 40 kms distance. And that is the exact distance just about between their respective epicenter locations. It was a tough pick in waveform view, because of the way the wave developed. It could have gone either way.

But again, the spectrograph wins, because using it I was able to determine that the mostly likely correct determination for S-wave arrival was chosen by EMSC and Chile. Even though I hate to admit it. But honesty first, and loyalties second.

I am going, in this case, with the EMSC and Chile epicenter locations for that 7.6 out at sea. The rest of you can take your pick. But let's just say it is an educated guess, supported by what I see in spectrograph view. It also makes more sense since Chile called for a tsunami alert. If it wasn't out at sea, they probably wouldn't have for a 7.6 on land.

Sorry USGS, but this time: you lose. Revisit your analysis please and relocate that quake.

reply to post by TrueAmerican


Thank you TA.

So you still maintain that this is the start of 'something new' given its intensity rather than an aftershock?

Rainbows
Jane

reply to post by angelchemuel


The start of something "new" happened when I saw the trouble beginning and posted this thread way back on March the 16th. And arguably, earlier than anyone else on the entire internet, if I do say so myself. Sorry if that sounds conceited. But it's the damn truth as far as I know. Uh oh, gotta run, Yellowstone just lit up again with a quake.... hmm let's see here... what we got...

meh, 2.3 or so out in the west of the park, followed by a couple other smaller ones.... Hmm, more coming in now...small. No biggie.


See here...
www.quake.utah.edu...

But that's getting off topic. Please forgive me oh off topic gods...



Oh dear I was off by .1 mag... 2.4...so sue me...
earthquake.usgs.gov...

reply to post by TrueAmerican


I am more concerned about Japan. I read earlier that they had a 4 (which is small) however, due to the issues at Fukishima... any quake is cause for concern.

I am also concerned about volcanic activity... volcano in that area has become active.

I feel a lot of this activity is a direct consequence of the oil and gas exploration and drilling in the North & South Pacific Oceans.

oh well... oil and gas are so important! /sarcasm.

reply to post by Thurisaz


Well that's nice that you're concerned about Japan. I'm sure the Japanese appreciate it. Even though I'd be willing to bet just about every single Japanese seismologist is keeping their eyes glued to the screens watching Chile right about now... But that's besides the point...Right?

update on post by muzzy

here is the graph updated to 427 hours elapsed, and the missing 30th March data found and added.
Recalibrated to ML for that 1st one 7.0ML (6.7Mw), I haven't had time to do those last 3.
Won't bother with a screenshot, here is the graph itself, same address as the old one so clicking the old screenshot one page back will work too.
Damn, I'm going to have to redo the entire series to add "foreshock" times to the events before the 8.2Mw as that is now the "Mainshock" not the 7.0ML at the start. I'll do it like the early part of the 2013 Cook Strait Series, where there were 3 main events and I put in the various time elapses relating to each main event. Excel job for the weekend.

reply to post by TrueAmerican

Very interesting set of events here we have. Thank you for being on top of this and sharing your insights with us. Fascinating that you mention the 1960 quake here as it is also discussed in a paper linked below.

reply to post by Rezlooper

Those die offs could very well be linked to increased gas emissions due to similarly increased deeper geophysical reactions; not the least of which is the increased mass production in certain zones of which this is a very active one.

As an excess mass generation episode takes place, the non-trapped matter is released in the form of gasses and liquids:



This happens in areas of positive gravity anomalies which is the result of the build up of excess mass generated within the core:



The Solid, Quantified, Radiating and Growing Earth

reply to post by Olivine

Indeed you are correct in that there are people who think that something other than subduction is what is occurring and I am one.

Take for example the aforementioned paper:

A large seismic event struck the Chilean coast at 19.10:40 UT on May 22, 1960 (Plafker and Savage, 1970; Cifuentes, 1989; Cifuentes and Silver, 1989). The hypocenter was at 38.05°S – 72.34°W and the focal depth was estimated around 35 km, similar to the Sumatra earthquake. A recent relocation (Krawczyk and the SPOC Team, 2003) provides a more western and slightly deeper hypocenter > 73° 05’ W, 38° 15’ S, H = 38.5 km). 

… 

The records suggest that a large slow and silent foreshock took place on the deepest portion of the fault 15 minutes before the main shock, with a seismic moment comparable to that of the main event (Plafker and Savage, 1970; Kanamori and Cipar, 1974; Lund, 1982; Cifuentes, 1989; Cifuentes and Silver, 1989). Lund (1982) assumed that a solitary wave (soliton) was generated by this foreshock of 7.9 Mw. This precursor was detected on the strainmeter at Pasadena. It was modelled tentatively – using the observed surface deformation (Figure 10a) – by Linde and Silver (1989). The moderate uplift of the coastline was explained as a double slope fault that started to slip slowly at the deepest edge (Linde and Silver, 1989). In this case, the rupture would have to nucleate in the subcrustal ductile lithosphere where the stress produced by the subducting slab would dissipate. 

emphases mine

Geodynamics of the Wadati-Benioff zone earthquakes: The 2004 Sumatra earthquake and other great earthquakes



Tons other examples of "subduction" earthquakes producing prodigious amounts of uplift are discussed in the paper, which is exemplary of extrusion:



rather than subduction:

Seven years lurking on ATS and I must say that TA you are amazing with the work and dedication you show here. There are others I know, but what I like about you is that you don't hesitate to show when things look bad. Keep up the great monitoring.

Now for an actual question. What magnitude of quake would we need to see now to continue to worry, or is that 7.6 already cause enough for concern?

reply to post by magnum1188


Are you saying you lurked for seven years without joining, and had to endure those ads in between the posts, the white background, ads flying everwhere, not seeing the avatars and signatures, why....that's dedication. Welcome to the funhouse, and please stick around and play.

Aleister
reply to post by magnum1188

 

Are you saying you lurked for seven years without joining, and had to endure those ads in between the posts, the white background, ads flying everwhere, not seeing the avatars and signatures, why....that's dedication. Welcome to the funhouse, and please stick around and play.

Not to go much off topic off the bat, but yes nothing but ads and white background. Now im in the big leagues

magnum1188
Seven years lurking on ATS and I must say that TA you are amazing with the work and dedication you show here. There are others I know, but what I like about you is that you don't hesitate to show when things look bad. Keep up the great monitoring.

Now for an actual question. What magnitude of quake would we need to see now to continue to worry, or is that 7.6 already cause enough for concern?

Thanks, and welcome to ATS. Albeit a little late. You mean all that time you've been watching me? Oh dear. I wonder how many more there are like you, lurking in the shadows and missing all the fun! Darn it, come out and play! Just don't use your real name. As to your question- enough has happened already with this for there to be considerable suspicion of both the 8.2 and 7.6 being possible foreshocks to something bigger. Basically anything else within one mag of that 8.2 will continue to sound my alarm bells. And those bells are going to continue to ring now, even without an additional foreshock, for at least another week, if not two or three.

And speaking of that 7.6, an interesting development has occurred folks. The USGS reconsidered, and relocated that 7.6 to out at sea. Making the other thread about the aftershock...Well... kinda wrong. It was not on land, it was out at sea.

Look where it is now:


Now whether or not my post above had anything to do with that... lol. I dunno. But seems like someone else up there finally agreed. And let's just say that I am aware that at least one or more people I know of at USGS for sure has visited this forum in the past. And that's all you'll get out of me on the subject folks, so don't ask who.

And I don't really care if my post had anything to do with it. The bottom line is they changed it, and that's what matters.

In the meantime, the fault still moves, continuing to spawn quake after quake. Waiting for it to die down for like at least a full day, but so far, that seems to be nowhere in sight. Warning still very much active, to the entire Chile and Peru coastline. And Lima, Peru... Better wake up and prepare, just in case.

Being quite new to what the mechanics of earthquakes and plate movements, I will not claim to know anything at all about whats going on.

Based on the amount of activity and where they are located is there any way to estimate the length of faults rupture if a larger one was to occur?

reply to post by magnum1188

The current activity March-April has a Fault length of 235km, not enough for a Mag 9.
But it could start to unzip north or south at any time.
that 7.6Mw was 36km from the southern most event in the series so far, which is what is of concern, why is it not in the main bunch?.
The 2010 M8.8 aftershocks were quite widespread, over 780km Fault length, based on just the M5+ aftershocks over 2 months
goo.gl...

muzzy
reply to post by magnum1188

 

The current activity March-April has a Fault length of 235km, not enough for a Mag 9.
But it could start to unzip north or south at any time.
that 7.6Mw was 36km from the southern most event in the series so far, which is what is of concern, why is it not in the main bunch?.
The 2010 M8.8 aftershocks were quite widespread, over 780km Fault length, based on just the M5+ aftershocks over 2 months
goo.gl...

Is this the same type of activity that preceded the 2011 japanese earthquake?

Could this also spread activity further north and cause problems in the western us?

reply to post by magnum1188

not really the same, its been going on for 19 days now at Chile, Japan was just a matter of a few days from the first 7.3 to the 9.0
this page has foreshocks and aftershocks for that 9.0 Tohoku earthquake on March 11, 2011

there is no evidence from anywhere or any series of events that one quake can trigger another over distances such as 8000km
the western US has its own geology

I just want to thank you folks for keeping up informed in your educated manner. I'm dumber than a box of rocks about these things but am fascinated so I really enjoy learning from your posts---but have to admit that sometimes when I open the posts it does make the hairs on my neck stand up.
Living in the New Madrid fault zone, I've only felt one real scary shaker. I was a teen at the time and I have to say it was a life-changing moment to feel the very earth moving in strange ways under my very feet and see the field looking like waves on the ocean! Since that time they've all been small, enough to make the coffee mug dance across the table sometimes but nothing more.
Anyway, thanks for the work you put in to educate and inform us.

I like this topic, it is important to keep tabs on this area. Not the least the risk of a Tsunami over here in NZ like back in 1960.

Here is looking at the whole series from another angle.
First you need the graph (up to 05/04/2014 02:48:39UTC)

(click image for larger version, opens in new tab/window)

I see 5 distinct parts to the series, so I want to know if these were in different areas or what?

Map shows icons (events) coloured by Time, each colour is one of the 5 parts of the series, the colour starts with a bigger icon for the event that triggered the next run of events (aftershocks) up to the next big event.
Large Pink = 7.0ML -16/03/2014 21:16:29
Small Pink = aftershocks of that up to;
Large Orange = 5.8ML - 22/03/2014 12:59:54
Small Orange = aftershocks of that up to;
Large Red = 6.1ML(6.2Mw) -23/03/2014 18:20:00
Small Red = aftershocks of that up to;
Large Blue = 8.2Mw - 01/04/2014 23:46:45
Small Blue = aftershocks of that up to;
Large Green = 7.6Mw - 03/04/2014 02:43:15
Small Green aftershocks of that up till now

(click image for interactive map, opens in new tab/window)

Interesting eh?
Orange series was North of the Pink series
then the Red Series East of that, and NE of the Pink series
Then the Blue Series (the 8.2, which itself was centered right between the Orange and Red Series), was more widespread and covered the entire area
Then the Green series ( the 7.6) quite a bit to the South.
Of course some of these intersperse with the others, but the general trend can been seen quite clearly.

EDIS Number: EQ-20140405-397035-CHL Common Alerting Protocol
Magnitude: 5.4
Mercalli scale: 6
Date-Time [UTC]: 05 April, 2014 at 04:22:38 UTC
Local Date/Time: Saturday, April 05, 2014 at 04:22 at night at epicenter
Coordinate: 32° 41.970, 71° 22.698
Depth: 32.17 km (19.99 miles)
Hypocentrum: Shallow depth
Class: Moderate
Region: South-America
Country: Chile
Location: 0.18 km (0.11 miles) SE of Hacienda La Calera, Region de Valparaiso, Chile
Source: USGS

hisz.rsoe.hu...

I'm heading out.......but this looks at first glimpse that it is migrating south .
I was alerted by a friend on another forum who lives in the capital Santiago who felt it for about 2 minutes...to quote...

We fInally had a shake in Santiago,(not an Earthquake), lasted 2 minutes, but luckily everything returned to normality fast

11:35PM, time in Chile. (10 to 4AM in London)

5,8 Richter. With Epicentrr in quillota.

No more news for now.

Rainbows
Jane

This from earthquake report....

Santiago - There was a deep rumble and lots of shaking, scaring us to immediately head for the front door, many people who were already outside listening to music and other things, began screaming. Took awhile to calm down. Still shaking while writing this note.
mendoza - senti un leve movimiento estando sentada y el crujir de la puerta cerrada
GEOFON Near Coast Of Central Chile Apr 05 02:22 5.6 10 MAP I Felt It
Santiago - Heard the eerie rumbling/roaring noise and then everything started shaking. The door rattled, the ground beneath us was shaking and it was really scary. We were ready to run to the doors but then the shaking subsided.
Santiago - Ich spürte ein schütteln und dröhnen.

earthquake-report.com...