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Author Topic: PIG has calved  (Read 185245 times)

solartim27

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Re: PIG has calved
« Reply #600 on: September 13, 2016, 10:23:18 PM »
The calving front is progressively retreating upstream & it seems plausible to me that crevasse upstream of calving front might rupture sometime in the late July to mid-August 2016 timeframe.

This did not come to pass, but I think it's going to soon.  Gif dates are 8/31 and 9/12.  When zoomed in, it looks to me like the crack is propagating diagonally down to the coast towards the bottom right corner.  Ice island is just off screen in the later shot.

http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SSH_20160912T042739_E260_S_1.final.jpg


http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SSH_20160831T042738_E6CA_S_1.final.jpg
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AbruptSLR

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Re: PIG has calved
« Reply #601 on: September 14, 2016, 12:03:32 AM »
The calving front is progressively retreating upstream & it seems plausible to me that crevasse upstream of calving front might rupture sometime in the late July to mid-August 2016 timeframe.
This did not come to pass, but I think it's going to soon.  Gif dates are 8/31 and 9/12.  When zoomed in, it looks to me like the crack is propagating diagonally down to the coast towards the bottom right corner.  Ice island is just off screen in the later shot.

In Reply #452, I state: "As a side-note I speculate that the next major rift will form a failure mechanism by about July 2016 with a major calving following sometime between July 2016 and November 2016, depending on boundary conditions and on whether fast sea ice is present."  So I still have a chance of being partially correct (or at least not totally wrong) ;D.
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oren

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Re: PIG has calved
« Reply #602 on: September 14, 2016, 12:23:45 AM »
Out of curiosity, I wanted to find out how long the grounded iceberg stayed before it finally went away.
Amazingly enough, it was more than a year!
It calved at the end of July 2015 with most of the calved ice disappearing away. The grounded part broke up mid-August with another piece floating away, and ever since then our PIG-headed iceberg just kept holding on.
Would it be fair to speculate that the glacier is partially grounded at this area? If a calved iceberg can stay grounded for so long, it must mean it was grounded before the calving as well.
To entertain more idle speculation, would the calving and subsequent removal of this iceberg reduce the buttressing of the PIG?

DoomInTheUK

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Re: PIG has calved
« Reply #603 on: September 14, 2016, 12:41:29 PM »
It could imply the the iceberg was stuck on the grounding line and the calving front has now moved back off the grounding line. Not a nice thought.

solartim27

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Re: PIG has calved
« Reply #604 on: September 16, 2016, 05:37:55 PM »
It could imply the the iceberg was stuck on the grounding line and the calving front has now moved back off the grounding line. Not a nice thought.
The berg was just stuck on a pinnacle, there were quite a few posts on the grounding line retreat back on pages 8 - 9, and on some other threads, it is well back from the front of the ice shelf.  I have not seen anything recently, but I expect the El Nino did cause it to retreat quite a bit. It was interesting to review the discussions of the retrograde beds in the area.
Here is the first clear image of the year, from Terra.  looking back at the last calving, the crack then was much more defined before it went.  Maybe the snow hills on top were fooling me into thinking I saw crack propagation.
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Adam Ash

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Re: PIG has calved
« Reply #605 on: September 20, 2016, 10:09:26 AM »
PIG's TwiddleBerg seems to have gone west.  It was about 10 km long (roughly), and the only likely candidate for it is among the broken ice at the lower of this view, about 50 km away from where it started.  Not certain, tho.

Wipneus

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Re: PIG has calved
« Reply #606 on: September 28, 2016, 07:09:30 PM »
Meanwhile the glacier is advancing and the crack widening. Here is a detail of the right hand side where widening and lengthening in the 60 day span is clear. Both images in the animation are aligned on the crack, noting the displacement the glacier was moving 11.6 m/day.

Wipneus

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Re: PIG has calved
« Reply #607 on: October 08, 2016, 05:21:40 PM »
First usable Landsat image of the summer season is in. Still cloudy but the crack is visible. Here is an animation made with the last available image of the previous season showing the visible crack has both widened and lengthened by about 50%.

Must click to start as the crack does not fit anymore in the standard 700x700 box.

oren

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Re: PIG has calved
« Reply #608 on: October 08, 2016, 07:12:49 PM »
By layman analysis, looks like it's going to calve this summer. If it does, it will be another retreat of the calving front.


AbruptSLR

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Re: PIG has calved
« Reply #610 on: October 19, 2016, 12:23:42 AM »
Did something break? Is this area part of PIG?

The image shows sea ice breaking away from the Thwaites Ice Shelf; so the image does not indicate any significant iceberg calving.

Best,
Dale
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prokaryotes

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Re: PIG has calved
« Reply #611 on: October 19, 2016, 01:05:17 AM »
The image shows sea ice breaking away from the Thwaites Ice Shelf; so the image does not indicate any significant iceberg calving.

Best,
Dale

For clarification, the topic is about large calving event, the iceberg is referred to as B31, first cracked then stalled, then finally begun moving around 2013
http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=82392

Then drifted along 2014
http://earthsky.org/earth/nasa-is-tracking-a-gargantuan-iceberg-escaped-from-antarctica


Correct? Thanks.

oren

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Re: PIG has calved
« Reply #612 on: October 19, 2016, 01:16:55 AM »
For clarification, the topic is about large calving event, the iceberg is referred to as B31, first cracked then stalled, then finally begun moving around 2013
...
Correct? Thanks.
The topic has since moved on to discuss other PIG calvings as they happen.

prokaryotes

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Re: PIG has calved
« Reply #613 on: October 19, 2016, 01:26:07 AM »
The topic has since moved on to discuss other PIG calvings as they happen.

Ok, but the original iceberg, is that now the one known as B31?
http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=82392

I am asking, because i am currently editing a video (the 3rd one here https://svs.gsfc.nasa.gov/11135 ), and want to update the information. Thanks


AbruptSLR

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Re: PIG has calved
« Reply #614 on: October 19, 2016, 01:13:55 PM »
For current information about the locations of large Antarctic icebergs, see:

http://www.scp.byu.edu/current_icebergs.html
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jai mitchell

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Re: PIG has calved
« Reply #615 on: October 26, 2016, 06:23:37 PM »
Update of Rignot's work on West Antarctic Pasin

video presentation 2 minutes

https://www.youtube.com/watch?v=YQMtb1Pd07E
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Wipneus

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Re: PIG has calved
« Reply #616 on: November 01, 2016, 07:07:03 PM »
First Sentinel 2 image is available and is brilliant! It is part of what ESA describes as a:
special acquisition campaign of Antarctica between 17th and
27th October (one repeat cycle), taking benefit of the margin currently offered
by the reduced illumination at Northern latitudes.

Hopefully Antarctica will share some more of those benefits while the illumination in the NH stays low.

Attached is a 20m/pix image covering the whole crack (about 150m wide in the middle).The second image covers the southern tip of the crack showing some beautiful details at 5m/pix (oversampled from native 10m/pix).

solartim27

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Re: PIG has calved
« Reply #617 on: November 07, 2016, 05:38:33 PM »
Here's a nice shot from https://twitter.com/NASA_ICE 
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AbruptSLR

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Re: PIG has calved
« Reply #618 on: December 01, 2016, 12:19:43 AM »
The calving front is progressively retreating upstream & it seems plausible to me that crevasse upstream of calving front might rupture sometime in the late July to mid-August 2016 timeframe.
This did not come to pass, but I think it's going to soon.  Gif dates are 8/31 and 9/12.  When zoomed in, it looks to me like the crack is propagating diagonally down to the coast towards the bottom right corner.  Ice island is just off screen in the later shot.

In Reply #452, I state: "As a side-note I speculate that the next major rift will form a failure mechanism by about July 2016 with a major calving following sometime between July 2016 and November 2016, depending on boundary conditions and on whether fast sea ice is present."  So I still have a chance of being partially correct (or at least not totally wrong) ;D.

As it is Nov 30th and no major calving occurred for the PIIS, it is reasonable to conclude that my forecast was too bullish.
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CraigsIsland

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Re: PIG has calved
« Reply #619 on: December 01, 2016, 12:43:58 AM »
The calving front is progressively retreating upstream & it seems plausible to me that crevasse upstream of calving front might rupture sometime in the late July to mid-August 2016 timeframe.
This did not come to pass, but I think it's going to soon.  Gif dates are 8/31 and 9/12.  When zoomed in, it looks to me like the crack is propagating diagonally down to the coast towards the bottom right corner.  Ice island is just off screen in the later shot.

In Reply #452, I state: "As a side-note I speculate that the next major rift will form a failure mechanism by about July 2016 with a major calving following sometime between July 2016 and November 2016, depending on boundary conditions and on whether fast sea ice is present."  So I still have a chance of being partially correct (or at least not totally wrong) ;D.

As it is Nov 30th and no major calving occurred for the PIIS, it is reasonable to conclude that my forecast was too bullish.

there's a few hours left (I think) for the 30th. maybe it happens tomorrow? lol. I think your estimation was reasonable and we'll see when/how/if that estimation can help us to understand a bit better about later possible calving.

Tealight

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Re: PIG has calved
« Reply #620 on: December 01, 2016, 12:53:32 AM »
I've taken some dimensions with SNAP. If the rift continues in a straight line the calved iceberg will be roughly 8.8km x 39km. The total area is 326km2. This is in a completely different league than anything from Greenland.

Wipneus

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Re: PIG has calved
« Reply #621 on: December 05, 2016, 05:21:00 PM »
No need to explain, I suppose. Sentinel 2 images scaled to 5m/pix, 6 weeks apart.

oren

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Re: PIG has calved
« Reply #622 on: December 05, 2016, 05:55:52 PM »
No need to explain, I suppose. Sentinel 2 images scaled to 5m/pix, 6 weeks apart.
Wow.

Greenbelt

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Re: PIG has calved
« Reply #623 on: December 06, 2016, 10:45:54 PM »
No need to explain, I suppose. Sentinel 2 images scaled to 5m/pix, 6 weeks apart.

In this image comparison, the features in the "upper" part (above the crack) look to be moving "up and left" while those in the "lower part" look to be moving down and left?  Thus the cracking, I suppose.

solartim27

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Re: PIG has calved
« Reply #624 on: December 10, 2016, 08:45:10 PM »
This series is also about 6 weeks apart, Oct 28 to Dec 8.  Different satellites, so the pairing may not be ideal, sure looks like it gets a lot longer.

http://www.polarview.aq/images/105_S1jpgfull/S1B_EW_GRDM_1SSH_20161209T044310_189A_S_1.final.jpg

S1A_EW_GRDM_1SSH_20161028T044353_32E1_S_1.final.jpg
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Tealight

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Re: PIG has calved
« Reply #625 on: December 11, 2016, 01:58:35 PM »
Last year in November A-Team and Nukefix posted a few images of fault lines on Pine Island Glacier spanning across several square kilometers. The area begins approx. 125km upstream from the calving front. Their posts start at #454.

Now I looked the areas again with Sentinels 2A, 10m resolution in RGB colour. This gives us a new perspective compared to Landsats 15m grey scale or even lower resolution radar.

Most noticable is the deep blue inside those cracks. I'm not sure if its liquid water or simply a shadow on blue ice. Some cracks on the third image show light blue areas without a shadow. The question with liquid water is where the energy comes from to melt ice. Maybe geothermal heat propagates from the bedrock all they way through the glacier to the surface. Hot steam would surely be capable of melting the surface of these edges. Does anyone has a different idea?


steve s

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Re: PIG has calved
« Reply #626 on: December 11, 2016, 09:42:33 PM »
Tealight,

The dark areas look like places where snow bridges did not form or collapsed. I think the curved crevasses in the third image, with the obvious wind-formed ridges of snow crossing some crevasses, may show the main bridging process.

solartim27

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Re: PIG has calved
« Reply #627 on: December 15, 2016, 06:42:13 PM »
Here is a visual worldview gif from Nov 8 to Dec 13, Aqua band.  Minor calvings in the notches on either side of PIG, and along the front.  I've left it full size, so click to animate.  (Bummer that worldview seems to be down with the full moon tides)

I think there is some interesting activity along the SW Tributary boundary at the bottom right of the image, previously discussed in this thread:
This will cause the buttressing on the SW Tributary Glacier to be reduced, which will help to trigger the acceleration of ice velocities for Thwaites:
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solartim27

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Re: PIG has calved
« Reply #628 on: December 17, 2016, 08:39:01 PM »
Here's a Sentinel gif from Dec 3 to 17.  Looks to me like both PIG and the Tributary are going to go soon.  One image small, and one left full size.

http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SSH_20161217T042738_2F36_S_1.final.jpg

S1A_EW_GRDM_1SSH_20161203T044353_2FFE_S_1.final.jpeg
« Last Edit: December 17, 2016, 09:01:34 PM by solartim27 »
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solartim27

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Re: PIG has calved
« Reply #629 on: December 17, 2016, 09:10:14 PM »
Here's a zoomed in gif of the boundary area from above.  It's full size to see the crack development.  (Clicking didn't work for me, but it did animate when I selected "Open in a new tab".  Of course you could just zoom in on that area in the full gif in the post above.)
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Wipneus

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Re: PIG has calved
« Reply #630 on: December 24, 2016, 12:14:00 PM »
The crack is widening fast.  It can not be long now.

Wipneus

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Re: PIG has calved
« Reply #631 on: December 24, 2016, 12:26:18 PM »
Another one, magnified 4 times to 2.5 m/pix, shows the western tip of the crack.

Hans

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Re: PIG has calved
« Reply #632 on: December 25, 2016, 06:16:59 PM »
Not knowing exactly where PIG was, I started google maps. I was surprised by the details of some photo's. Not the most recent ones, of course, But nevertheless worth a visit
https://www.google.nl/maps/@-75.0761623,-101.4182596,3682m/data=!3m1!1e3
Zooming in and wandering around gives some nice details.

oren

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Re: PIG has calved
« Reply #633 on: December 26, 2016, 12:19:52 AM »
Thanks Hans, I never realized Google might have this level of detail. It's funny how the PIG crack is highly detailed in one tile but non-existent in the next one.

bbr2314

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Re: PIG has calved
« Reply #634 on: December 26, 2016, 03:27:20 AM »
Looking at EOSDIS it seems as though the entire front is now moving forward noticeably, perhaps crack has greatly expanded?

iwantatr8

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Re: PIG has calved
« Reply #635 on: December 27, 2016, 07:57:41 AM »
Looking at the latest sentinel here
http://www.polarview.aq/images/105_S1jpgfull/S1B_EW_GRDM_1SSH_20161226T045115_30DF_S_1.final.jpg
(Warning large photo)
There appears to be a new crack starting 1/3 of the way back from the face to the larger crack we've been following.
A race now I feel, between this and the existing crack as to which will be the first to calve.
I'm not sure that we will see anything this year given the few days left but early January seems likely.

Sorry for the lack of an image, posting from a mobile.

Iceismylife

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Re: PIG has calved
« Reply #636 on: December 27, 2016, 05:39:01 PM »
Thanks Hans, I never realized Google might have this level of detail. It's funny how the PIG crack is highly detailed in one tile but non-existent in the next one.
Put a pin in where it isn't and it will trigger updating.  (on occasion)

Wipneus

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Re: PIG has calved
« Reply #637 on: January 07, 2017, 10:17:42 AM »
The calving-in-progress continues...

frankendoodle

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Re: PIG has calved
« Reply #638 on: January 07, 2017, 10:26:23 PM »
When the glacier fully calves the iceberg will be about the size of the island of Grenada in the Caribbean.

Wipneus

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Re: PIG has calved
« Reply #639 on: January 25, 2017, 09:09:42 AM »
Two Landsat 8 images, 16 days apart (so taken from identical satellite positions), suggest that the near future big calving is moving and rotating relative from the main glacier.

solartim27

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Re: PIG has calved
« Reply #640 on: January 27, 2017, 12:22:28 AM »
Some action at the front, small calving.  Terra images from 25 and 26.  Aqua is too
 cloudy.
« Last Edit: January 27, 2017, 12:34:09 AM by solartim27 »
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Wipneus

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Re: PIG has calved
« Reply #641 on: January 27, 2017, 10:41:47 AM »
It is big enough, could be the start.

(click for the big picture)

Wipneus

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Re: PIG has calved
« Reply #642 on: January 27, 2017, 11:17:31 AM »
Detail shows a fine crack where the next calving will go. How far will this crack extend?

oren

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Re: PIG has calved
« Reply #643 on: January 28, 2017, 08:39:05 AM »
Dumb question time. How is PIG related to the long Larsen C crack shown here:
It's unrelated: PIG is a glacier with an ice shelf at the end, Larsen C is an ice shelf with several glaciers behind it. Larsen C is east of the Antarctic Peninsula, PIG is in West Antarctica. PIG calving period is years, Larsen C is decades. Calving size is smaller in PIG. PIG is much more important as it drains a large part of West Antarctica. Hope I helped a bit, but perhaps you can clarify what you meant: Geographically? Same processes? etc.

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Re: PIG has calved
« Reply #644 on: January 28, 2017, 10:25:27 AM »
Dumb question time. How is PIG related to the long Larsen C crack shown here:
Hi Susan, I think the crack in LarsenC is around 150 km long now.
The full width of PIG is around 40 km
The length of the fraction that cracked of in the images of 26 January is.. well.. just a fraction of it. ;)

Susan Anderson

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Re: PIG has calved
« Reply #645 on: January 28, 2017, 10:42:28 PM »
Thanks oren and Hans, that's exactly what I needed and I was way off topic. I'm taking a closer look at the riches on the forum, a treasure trove (!), now have a much better idea of the geography and effects, and found a paper map. Time for some study! Meanwhile, it is all fascinating and bloody dangerous. My question almost defines dumb, and I see there's a place for that too! ;)

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Re: PIG has calved
« Reply #646 on: January 29, 2017, 12:48:46 AM »
Another big difference is how. Larsen |C started at an ocean point and is working its way across to another ocean point. much like tearing a piece of paper. The PIG is a very different story.
West Antarctic ice shelf breaking up from the inside out.
Rift in Pine Island Glacier ice shelf, West Antarctica, photographed from the air during a NASA Operation IceBridge survey flight on Nov. 4, 2016. This rift is the second to form in the center of the ice shelf in the past three years. The first resulted in an iceberg that broke off in 2015.
In the images, they saw evidence that a rift formed at the very base of the ice shelf nearly 20 miles inland in 2013. The rift propagated upward over two years, until it broke through the ice surface and set the iceberg adrift over 12 days in late July and early August 2015.
This article is telling about what happened in 2015, but based on caption of first photo which I quote, it seems to be the same process involved for this event.
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Susan Anderson

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Re: PIG has calved
« Reply #647 on: January 30, 2017, 06:53:35 AM »
I've removed the big Larsen C graphic and my query as it was so glaringly off topic and I don't think it was needed for the good answers y'all provided. Thanks everyone for the work here and elsewhere, an excellent range of visual and information aids.

Wipneus

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Re: PIG has calved
« Reply #648 on: January 31, 2017, 09:00:03 AM »
Five days later, no further calving yet.

solartim27

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Re: PIG has calved
« Reply #649 on: February 04, 2017, 05:22:21 PM »
Here is a gif from Jan 5 (?) to Feb 1 of the rift in the SW Tributary glacier next to PIG from
http://apps.sentinel-hub.com/sentinel-playground/#lat=-75.08856670583675/lng=-101.36260986328125/zoom=11/preset=CUSTOM/layers=B05,B03,B01/maxcc=8/gain=0.4/time=2015-01-01|2017-02-01/cloudCorrection=none/colCor=/evalscript=
The main crack in PIG was not updated between images so I cropped it off.  I'm not certain of the dates for the first image, which you can tell is a mosaic of two separate images.
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