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Author Topic: Halley base shut down and new crack in Brunt shelf  (Read 20123 times)

solartim27

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #50 on: October 29, 2018, 03:44:56 AM »
Here's a snip from the latest Polarview.  Looks like Chasm 1 has joined up with the Halloween crack, but hard to say for certain.  I find the straightness of the new crack section to be a concern, perhaps a data glitch in that area? Of course we just saw the rectangular bergs.  Even if it is all the way through, it still may not move significantly.  It also looks to me like there is also a crack extension heading to the coast, but perhaps I need to clean my glasses.
Original image 34 mb
https://www.polarview.aq/images/105_S1jpgfull/S1B_EW_GRDM_1SDH_20181027T231436_AC7B_S_1.final.jpg
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solartim27

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #51 on: October 30, 2018, 06:25:12 AM »
Okay, so that's two in a row, but it still looks weird.  Original 10 mb
https://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SSH_20181029T234745_234F_S_1.final.jpg
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solartim27

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #52 on: October 30, 2018, 05:29:29 PM »
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iwantatr8

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #53 on: October 30, 2018, 06:03:18 PM »
Here's a view switching between the 7th and the 27th Oct - you can clearly see the crack has extended and checking here https://apps.sentinel-hub.com/sentinel-playground/?source=S2&lat=-75.53564672956175&lng=-26.096477508544922&zoom=13&preset=1_NATURAL_COL0R&layers=B01,B02,B03&maxcc=85&gain=0.4&gamma=1.0&time=2015-01-01%7C2018-10-27&atmFilter=&showDates=true
at the crack tip shows this to be about 1 km over the 20 days.

i think we could be looking at a differently shaped ice shelf before xmas...

solartim27

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #54 on: November 05, 2018, 06:57:14 PM »
Very nice animation from July 30, 2016 to Oct 30 2018

https://adrianluckman.wordpress.com/2018/10/31/
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FrostKing70

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #55 on: November 05, 2018, 07:43:29 PM »
Interesting animations!   Does any one have access to information on how big (area and volume) the calving events would be from Chasm 1 and the Halloween Crack (when they eventually go, although I believe one or both will happen this summer)?

FrostKing70

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #56 on: November 06, 2018, 08:27:35 PM »
I have done some poking around on the internet and have not been able to find any indication of the potential size of the calving events.   Can any one point me towards to good source?

solartim27

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #57 on: November 07, 2018, 07:45:35 AM »
Here is a wider view of the Brunt Ice Shelf showing the other side of the Halloween Crack.  Looks like there is a chance for a significant  calving there.
Original image 53 mb https://www.polarview.aq/images/105_S1jpgfull/S1B_IW_GRDH_1SSH_20181106T233049_C2BC_S_1.final.jpg

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iwantatr8

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #58 on: November 20, 2018, 03:46:54 PM »
SolarTim27,

I think you are right, here's this month's animation showing the MIR area.
you can see that in the area above the widening Halloween crack there is another crack starting up across the area of the shelf that you have highlighted.

No sign of Crevasse 1 at this scale yet but my guess is that it won't be long.


FredBear

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #59 on: November 24, 2018, 10:39:09 PM »

FredBear

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #60 on: December 12, 2018, 06:34:56 PM »
  .   .   and Halley opened up again by BAS   .    . 

https://www.bas.ac.uk/media-post/summer-fieldwork-begins-at-halley

iwantatr8

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #61 on: December 13, 2018, 05:35:37 PM »
Looks like Chasm 1 has advanced some more - very close to calving now...

FredBear

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #62 on: December 21, 2018, 02:58:21 PM »
Just found this on the British Antarctic Survey site:-


SteveMDFP

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #63 on: December 26, 2018, 08:17:04 PM »
Turns out, the Halley crew doesn't just spend all their time dodging new cracks in the ice shelf.
They also monitor electronic signals related to space weather.
Some of these are low-frequency radio waves, corresponding to audio wavelengths.
So, they can just hook up the electronic signals directly into an audio recorder.
So, for your aural pleasure,

Listen to the Creepy Noises Picked Up at a Space Weather Station in Antarctica
https://gizmodo.com/listen-to-the-creepy-noises-picked-up-at-a-space-weathe-1831234519

solartim27

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #64 on: December 31, 2018, 03:55:45 AM »
Looks to me like there is significant crack development right to the left of the Longitude line.  That doesn't mean that if it does go all the way that the berg will move anywhere, or any time soon, but I feel there is a non-zero chance that Brunt could break apart this summer.
Snip from https://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SSH_20181230T233130_2AC8_S_1.final.jpg   (31 MB)
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solartim27

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #65 on: December 31, 2018, 04:04:15 AM »
Here's a worldview GIF from the end of November to the end of December. Hard to say if the crack really expanded that much, or if it's just surface snow melting, blowing, or something to make it more visible.  A nice Sentinel shot would be nice around now.
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solartim27

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #66 on: December 31, 2018, 05:24:21 PM »
There was an almost clear Sentinel shot of Brunt on the 29th.  Here's a gif from September until then from the playground in natural color, and a 2nd shot in the same area with the NDWI band selected. ( Note the 3 km scale bar in the lower right corner )
« Last Edit: December 31, 2018, 05:35:38 PM by solartim27 »
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iwantatr8

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #67 on: January 11, 2019, 02:42:16 PM »
Well, there was a clear image on the 8th Jan so here's the new year's animation.

Not a lot of changes -
expansion of the crack above the halloween crack radiating from the MIR
Movement around the MIR

There's been a suggestion on the SAR images of chasm 1 forking towards the tip, not really seeing anything in the visual images though.

I do like the NDWI band as a way to highlight the cracks.
 

solartim27

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #68 on: January 18, 2019, 07:38:07 PM »
World view is nice and clear today, hopefully we can get a visual shot this weekend.  Looks like the cracks might have joined up right upstream of the ice rise.
https://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SSH_20190118T002007_76A0_S_1.final.jpg  (32 MB)
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solartim27

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #69 on: January 18, 2019, 07:51:44 PM »
Worldview shows lots of development over the last four weeks, but the resolution is not high enough to see for certain.
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solartim27

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #70 on: January 19, 2019, 01:52:25 AM »
Sentinel came through today, gif from 29 Nov to 18 Jan, NDWI band.  Not quite there yet.
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iwantatr8

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #71 on: January 21, 2019, 05:26:34 PM »
 :o

getting very close now - maybe 5km between the cracks at this stage.

and an interesting article published in October - read it now before it becomes outdated news.
https://www.the-cryosphere.net/12/3361/2018/tc-12-3361-2018.pdf

solartim27

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #72 on: January 31, 2019, 09:58:46 PM »
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Stephan

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #73 on: February 10, 2019, 10:33:09 PM »
I just visited Sentinel images of the Brunt Ice Shelf. The Chasm 1 crack has lengthened about 2 km between Dec 29, 2018 and Feb 07, 2019. Its distance to the tip of the Halloween Crak is now only around 8 km. I wonder when these two cracks will meet and what happens thereafter...

iwantatr8

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #74 on: February 11, 2019, 01:51:21 PM »
Indeed, taking a look at the recent polarview IW image it's getting very close now.

It looks like chasm 1 will not meet the Halloween crack but just end with the calved section below the MIR on the image below.

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #75 on: February 13, 2019, 02:29:16 AM »
I found this image of the brunt ice shelf looking at the new thread of Antarctic expeditions.
https://www.bas.ac.uk/project/moving-halley/

It looks like some of what I thought was new growth is harder to see on some days.

Andreas T

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #76 on: February 14, 2019, 07:47:19 PM »
This paper looks interesting and has not been linked to before it seems:
https://www.the-cryosphere-discuss.net/tc-2018-206/tc-2018-206.pdf
one small quote:
Quote
However, the DEM surface topography (and ICESat data) shows large variations in the distribution of
the incorporated icebergs (Fig. 5), and the ice shelf draft upstream of the MIR (Fig. 6) which can be used to
determine if grounding will be maintained. For example, there are currently portions of the ice shelf, due to pass
over MIR 4-12 years from 2017 that may have insufficient draft to ground, with no keels extending below -200
m. At this time the ice shelf might be more prone to reduced, or loss of, contact (Fig. 6b).