This week at Davis we've hauled cable for infrasound, been out studying geophysics, removed the hut from Trajer Ridge and continued our search and rescue training.

Getting to know the Earth under the East Antarctic ice sheet and glaciers

During a couple of field seasons we’ve been collecting data to understand how the ice sheet interacts with the solid Earth beneath and how this interaction can help us to predict global sea level changes.

It’s not easy, as the rocks we are interested in are usually hidden under kilometres of ice, but we have a broad range of techniques to indirectly measure what is going on. This interdisciplinary approach is sometimes challenging but needed and rewarding.

When ice is melting, the Earth responds with an uplift, just as the mattress regains its shape when you step out of bed in the morning. We have deployed precise GPS–receivers on outcrops along the coast to measure the few millimetres of response when the mass of ice is changing.

The GPS–antennas are bolted onto the bedrock and prepared to, hopefully, survive for years in some of the harshest environment on this planet; the summits of nunataks and islands in East Antarctica.

It’s a rather emotional moment to leave the instrument at an outcrop that will not be visited for years. People who check twice if the stove is off wouldn’t enjoy the stress of flying away from a distant outcrop and suddenly start to doubt if that last blue cable was really connected.

We also deploy seismometers to measure seismic waves from distant earthquakes. The signals are used to calculate thickness and character of the continental plates and even estimate temperatures at depth. The sensors are buried in the ground, protected from the noise of wind and are surprisingly sensitive. I find it rather relaxing to convert the seismic signal to sound and listen to it to relax in my spare time.

A lot of interesting vibrations occur during the long isolated winters. Most of it sounds like frying greasy bacon when sped up 200 times or so, but sometimes there is an infrasonic fart or burp resonating through the icy continent that causes the billion years old mountains to shake a bit, as a distant memory of when they themselves where young and dynamic and rocked the world.

Finally we also collect rock samples for analysis back in Hobart and Canberra. This is purely classic geological labour and it literary means that we swing the geology hammer and crack a piece of weathered charnockite or gneiss, tuck it in a canvas bag and carry it around in the backpack for a day or two. Mawson or Taylor would have done it exactly the same way. We’ve only replaced the sledges with choppers and the huskies with pilots.

We are interested in how the ice extent has changed in the past. From the rock samples we can detect how long the rocks have been exposed to the sky and therefore when the site was last covered by ice. We also use the samples to constrain the geological domains, how old and rigid the rocks are.

Most amazingly, some rocks can tell a number of stories at once; the story of how it was formed, maybe 2.2 billion years ago, how it was later part of a number of mighty mountain chains, how it was ripped off and transported by a glacier and finally how it’s now sadly weathering in the wind and eventually ends up in the ocean as mud and maybe digested by some dull sea–worm. If nothing else, it’s a beautiful reminder to check the pension saving scheme in time.

We have already got useful samples and data that will eventually keep us busy for a good while in offices and laboratories back in Australia. This year we have finished the work from Casey and are now spending the days in The Vestfold Hills; waiting for good weather to deploy the last instrument and collect the last backpack of rocks.

We are in a good mood and lack nothing.

Toby, for the King project

Search and rescue training

Each winter season, all stations are required to have a search and rescue (SAR) team.

Over the summer months the station as a whole and a select group  designated as the search and rescue team undergo a range of training exercises.

This week our team met in the Green store with our three field training officers (FTOs), Chris, Gideon and Nick, to practice their knots, climbing and rescue techniques. After being kitted out the team went through the various ropes, knots, anchors, harnesses and rescue equipment. In three groups they practised their skills in belaying, and experienced their first taste of vertical travel using a prusik or two to ascend up the climbing wall.

Jen

Trajer Hut replacement — Phase 2

As an expeditioner of several seasons I felt sadly honoured to be one of a group that said a final goodbye to the Trajer Ridge melon. A cheerful, hot-dog shaped home, made of fibreglass and full of historic graffiti, it made a surprisingly graceful exit from its resting place of nearly thirty years.

Located within easy trudge of the plateau it held a promise of warmth and relaxation in an area often whistling with wind. It nestled cosily amongst some truly delightful scenery midway between Platcha and Watts Huts. It was decided to try and fly the melon to station in one piece rather than disassemble it in the pristine Trajer Valley, so several groups over several weeks have each had some involvement in preparing it for its epic final exit.

Myself, Wes (electrician) and Fitzy (plumber) had the last sleep (and graffiti!) in it on the rather inauspicious Friday the thirteenth of January as we secured the final nuts, bolts and straps that would make the flight possible.

Saturday saw the arrival of Euan (engineer), Lance (AGSO) and Matt (Senior AGSO) as the prime architects of the lift. Toby, Heli-Res pilot, was the skilled operator set to give the melon wings. Aged but still strong the big red landmark took to the air like a natural. Guided by a steady hand it touched down on the fringes of Davis station mere minutes later.

Another crew will go up and build a new deck. Yet another will erect a new, larger melon on the same spot. I hope another thirty years of cheerful goodwill will grace its cosy walls and the positive vibes of thankful expeditioners will seep into its furnishings.

The melon is dead! Long live the melon!

Rhys

Infrasound — laying the cable

Getting the cable out to the infrasound site has been epic. It’s involved many station personnel and a lot of hard work. Here are two perspectives of cable pulling from Mark, the engineer, and Ralph, the station doctor. 

Mark:

One of the key projects at Davis this summer is the installation of the infrasound monitoring station (IS03) within the Vestfold Hills about six kilometres from Davis station. Due to the location, the only way to get power and communications to site is to manually haul out the necessary cables from near the end of Dingle Road — approximately 2600 metres in total.

The inner monologue of Ralph: 

“Hey, great I have been invited cable dragging. It’s going to be so good to get out of the office to see what everyone is up to. I hope I am fit enough, the group that went out the other day said it was a bit of an effort. Weather looks good though. Bryce has made up a cable song, Sharky has told me about the singing, he’s a creative soul I’ll give him that”

Mark:

The approach is to set up the cable drum on a frame, line up, grab hold and start pulling the cables out. Basically a new person joins the line every 80 or so metres. However with the cable weighing 160 kilograms per kilometre, it is not possible to undertake the entire 2600 metres in a single haul. Basically every 700–800 metre cable needed to be spooled out on the ground and the whole process recommenced from there.

The inner monologue of Ralph: 

“So this is where they got it to yesterday, not a bad walk. The cable doesn’t look that heavy. Oh, we are going over the hill. Neat. Let’s do this, go team doctor!”

“Oh god, the hill, the hill, who thought this was a good idea! That view is amazing! Ok back to cable, mentally vexing cable.”

“How is Bryce still singing! How is this cable this heavy! How have people done this two days in row?”

“Why is there a penguin walking past, there is nothing but rock as far as the eye can see? Clearly you are lost.”

“One cable done. I have achieved something! We get a helicopter ride back! So worth it. Oh, now we start the next cable. Ok. Neat.”

Mark:

All four of the cables — three by high voltage power cables and an armoured fibre optic communications cable have reached the infrasound site. All that needs to be undertaken now is to load the cables and frame onto the back of the truck to feed it out along the side of the road the five or so kilometres back to Davis.

The inner monologue of Ralph:

“Bryce has stopped singing. That’s not a good sign.”

“So 800 metres to go, that means if we are making 50 metres per pull, I only have to walk over this stretch another…”

“That’s a pretty rock. I think you have gone mad. Hush”

“That was a long day. I need a drink. Oh, you are doing this again tomorrow, and next week…?”

“I have never been so physically exhausted after a single day of work, to know that there have been people going out day after day simply amazes me!”

Mark and Ralph 

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