March 14, 2016

Volta Glacier New Zealand Losing Lower Volta section

Posted by Mauri Pelto

volta compare

Comparison of Volta Glacier in 2001 and 2016.  Yellow arrow is the 2016 terminus position and the red arrow the NZ topo map terminus location.  Purple arrows indicate upglacier thinning and orange arrows regions of avalanching onto the lower Volta Glacier. 

Volta Glacier drains northeast from Mount Aspiring entering the Waiatoto River.  This region is 60 km south of the main region of glaciers around Mount Cook. The glacier is divided into two segments the upper Volta flowing west from Tantalus Rock at 2100 m to an icefall extending from 1600 m to 1400 m where the Lower Volta Glacier begins. The Lower Volta is also fed by steep glaciers that avalanche material onto the lower Volta Glacier from the south.  In the New Zealand Topo Map the lower Volta flows down an additional icefall to 1050 m.  The glacier has been noted as part of the pattern of the larger glaciers undergoing substantial retreat in New Zealand by NIWA (2007).  The volume loss of New Zealand glaciers is reported as 36% from 1978 to 2015, from 54 cubic km to 34 cubic km. In 2015 the average snowline was approximately 40 m higher than average leading to mass losses overall (NIWA, 2015)

In 2001 the Lower Volta Glacier still descended through the icefall to the terminus lobe at 1050 m. By 2010 the glacier terminated at the top of this icefall near 1200 m.  A 2012 Google Earth image indicates this position.  It is also evident that icefall connecting the upper and lower Volta has narrowed and flow has been reduced.  The heavily debris covered lower Volta in the 2012 image is clearly wasting away.  The 2016 Landsat image indicates continued downwasting of lower Volta Glacier.  The glacier has retreated 1600 m from the map position. Thinning of the upper Volta continues, purple arrows including the icefall is much narrower and bedrock areas are expanding in the region above the icefall. The upper Volta continues to retain significant snow covered areas throughout the years while the lower Volta does not. As the lower Volta Glacier continues downwasting rapidly the upper Volta downwasting is much slower.  The glacier has experienced significant retreat just like other New Zealand glaciers: Murchison, Mueller and Tasman.

volta map

New Zealand Topographic Map indicating flow of upper and lower Volta Glacier, blue arrows. Red arrow is the terminus location for the map and yellow arrow the 2016 terminus location.

aspiring 2012 ge

Google Earth image in 2012 of the lower Volta Glacier and the icefall connection.  The terminus diverges to the yellow arrows left and right. 


View across lower Volta Glacier to the southwest, from Mountain Recreation News