@article {Joughin2008a, title = {{Ice-front variation and tidewater behavior on Helheim and Kangerdlugssuaq Glaciers, Greenland}}, journal = {Journal of Geophysical Research: Earth Surface}, volume = {113}, number = {1}, year = {2008}, month = {jan}, pages = {1{\textendash}11}, abstract = {We used satellite images to examine the calving behavior ofHelheim and Kangerdlugssuaq Glaciers, Greenland, from 2001 to 2006, a period in which they retreated and speed up. These data show that many large iceberge-calving episodes coincided with teleseismically detected glacial erthquakes, suggesting that calving-related processes are the source of seismicity. For each of several events for which we hace observations, the ice front calved back to a large, pre-existing rift. These refits form where the ice has thinned to near flotation as the ice front retreats down back side of a bathymetric high, which agrees well with earlier theoretical predictions. In adition to recent retreat in a period of high temperature, analysis of several images shows that Helhaim retreated in the 20th Century during a warmer period and then re-adcanced during a subsequent cooler period. This apparent sensitivity to waming suggests that higher temperatures may promote an initial retread off a bathymetric high that is then sustained by tidewater dynamics as the ice front retreats into depper water. The cycle of frontal advance and retreat in less than a century indicates that tidewater glaciers in Greenland can advance rapidly. Greenland{\textquoteright}s larger resorvoir of inland ice and conditions that favor the formation of ice shelves likely contribute to the rapid rates of advance.}, isbn = {0148-0227}, issn = {21699011}, doi = {10.1029/2007JF000837}, url = {http://www.agu.org/pubs/crossref/2008/2007JF000837.shtml}, author = {Joughin, Ian and Howat, Ian and Alley, Richard B. and Ekstrom, Goran and Fahnestock, Mark and Moon, Twila and Nettles, Meredith and Truffer, Martin and Tsai, Victor C.} }