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Monthly Archives: May 2014 − News & Stories

Uplift of the nor­t­hern Ant­ar­c­tic Pen­in­su­la: result of tec­to­nics and ice loss

The pro­cess of land uplift as a con­se­quence of loss of lar­ge ice mas­ses is well known from nor­t­hern Scan­di­na­via and Spits­ber­gen, whe­re traces of such events inclu­ding rai­sed bea­ches can be seen in many places. In Ant­ar­c­ti­ca, it is more tri­cky as the­re is not much ice-free land.

Pre­cise GPS-mea­su­re­ments have reve­a­led recent uplift dyna­mics of the nor­t­hern Ant­ar­c­tic Pen­in­su­la. And not just that: while uplift was almost negli­gi­ble with 0.1 mm/year until 2002, the value jum­ped up to 8.8 mm/yr – an increase by a fac­tor of almost 90! This is remar­kab­le, both in terms of the deve­lo­p­ment and the abso­lu­te value of pre­sent land uplift: near­ly 1 cm/year is very fast, geo­lo­gi­cal­ly spea­king.

The col­lap­se of the Lar­sen B ice shelf in 2002 has been assu­med to be the main dri­ving force behind the land uplift: immense volu­mes of floa­ting shelf ice bro­ke off the east coast of the Ant­ar­c­tic Pen­in­su­la and floa­ted out into the Wed­dell Sea as lar­ge tabu­lar ice­bergs. The loss of form­er­ly land-based was a con­se­quence of the loss of the sta­bi­li­zing ice shelf. The result of such an immense loss of weight is iso­sta­tic rebound of the crust, lea­ding to land uplift.

Geo­phy­si­cal model­ling has now shown the ice loss to be insuf­fi­ci­ent to explain rate and deve­lo­p­ment of land uplift as obser­ved. Move­ments in the man­t­le, at 100 km depths and lower, need to be taken into account to explain the data ful­ly.

The Brans­field Strait, a small ocea­nic basin sepa­ra­ting the South Shet­land Islands from the nor­thwes­tern Ant­ar­c­tic Pen­in­su­la, is a tec­to­ni­cal­ly acti­ve area. The­re are seve­ral vol­ca­noes in the area that erupt­ed very recent­ly in geo­lo­gi­cal term, and seve­ral frac­tu­re zones and pla­te boun­da­ries.

Pen­gu­in Island: a young vol­ca­nic island in the geo­lo­gi­cal­ly acti­ve Brans­field Strait. Next to vol­ca­nism, land uplift is ano­ther con­se­quence of the­se tec­to­nics, ampli­fied by recent deg­la­cia­ti­on of the Ant­ar­c­tic Pen­in­su­la.

Penguin Island: a young volcanic island in the South Shetland Islands

Source: Earth and Pla­ne­ta­ry Sci­ence Let­ters

New sta­tis­tics for tou­rism in Ant­ar­c­ti­ca

The Inter­na­tio­nal Asso­cia­ti­on of Ant­ar­c­tic Tour ope­ra­tors has published new sta­tis­tics of tou­rism in Ant­ar­c­ti­ca. Num­bers for the now finis­hed 2013-14 sea­son are not fina­li­zed yet, but preli­mi­na­ry figu­res indi­ca­te a sta­ble deve­lo­p­ment wit­hout major chan­ges from pre­vious years. In the 2012-13 sea­son, a total of 34,316 tou­rists visi­ted Ant­ar­c­ti­ca, a figu­re not expec­ted to chan­ge too much for 2013-14. Accor­ding to a pro­gno­sis for 2014-15, expec­ted visi­tor num­bers of 36,545 indi­ca­te a future growth of 6-7 %.

The­re have not been lar­ge fluc­tua­tions sin­ce 2009-10: visi­tor num­bers have lar­ge­ly been sta­ble bet­ween 34,000 and 36,000, with the excep­ti­on of the 2011-12 sea­son, when num­bers drop­ped down to 26,500 fol­lo­wing the ban on hea­vy oil as ship fuel in the Ant­ar­c­tic Trea­ty area. As a con­se­quence, some lar­ger ships drop­ped Ant­ar­c­ti­ca as a desti­na­ti­on. A good deve­lo­p­ment from an envi­ron­men­tal per­spec­ti­ve, con­side­ring the poten­ti­al­ly dra­ma­tic con­se­quen­ces of a spill of hea­vy fuel/crude oil.

Out of about 35,000 tou­rists visi­ting Ant­ar­c­ti­ca, a lar­ge majo­ri­ty of 71 % is tra­vel­ling to the Ant­ar­c­tic Pen­in­su­la with small to medi­um-sized ships with fewer than 501 pas­sen­gers. The­se ships offer landings to their pas­sen­gers. As the maxi­mum num­ber of tou­rists ashore is limi­t­ed to 100, ships with more than 100 pas­sen­gers offer a rota­ti­on sys­tem.

Ships with more than 500 pas­sen­gers do not offer landings, they con­sti­tu­te the “crui­se only” cate­go­ry, which descri­bes exact­ly what they are doing (and what not). 27 % of ant­ar­c­tic tou­rism is crui­se only.

The pro­por­ti­on of tho­se who visit the inte­ri­or of Ant­ar­c­ti­ca by flight is small, num­be­ring about 1 %. This includes visits to the South Pole and moun­tai­nee­ring expe­di­ti­ons to Mount Vin­cent, the hig­hest moun­tain of Ant­ar­c­ti­ca.

Expe­di­ti­on crui­se ships at the South Shet­land Islands: this is how most tou­rists visit Ant­ar­c­ti­ca. MS Nordn­or­ge to the left, MV Gri­go­riy Mik­heev (not ope­ra­ting any­mo­re) to the right. A govern­men­tal sup­p­ly ship in the back­ground.

Tourism, Antarctica: ships at the South Shetland Islands

Source: IAATO


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