[ghsc-seminars] Tomorrow (Thursday) @ 10am: Mylène Jacquemart, CU Boulder

[Benjamin Mirus]

*"**Instantaneous glacier loss through catastrophic collapse: Insights from
remote sensing analysis and field observations at Flat Creek Glacier,
Wrangell St. Elias National Park and Preserve**"*

*Mylène Jacquemart*
*CU Boulder*

In 2002, Kolka glacier, a surge-type glacier in the Russian Caucasus,
detached catastrophically and turned into a destructive debris-flow of
historical dimensions that killed more than a hundred of people (Evans et
al., 2009; Häberli et al., 2004). In 2016, two neighboring glaciers in the
Aru range, Tibet, catastrophically lost their tongues, revealing a similar,
practically instantaneous mode of glacier loss (Kääb et al., 2018). Mostly
unreported, to date, is a failure in Alaska’s Wrangell - St.Elias National
Park and Preserve, that, at first glance, shares some surprising
similarities with the events in Tibet and Russia. A comparison of 2014 and
2016 ArcticDEM digital surface models (DSM), as well as corresponding
Planet Labs optical images, reveals that a significant portion of the
glacier has been lost in what appears to be two large mass failures in 2013
and 2015. Both events produced very long runouts of about 12km (angle of
reach <7°), travelled over flat terrain on a forested fan and deposited
debris over several km2. The 2015 failure tore into the ridgeline at the
head of the drainage, removing about 100m of the glaciated ridge. Between
the two events about 20 million m3 of ice and possibly rock were lost, an
amount similar in magnitude to the events in Tibet (60 – 80 million m3).
Interestingly, and analogous to both Aru and Kolka, the area is home to
numerous surging glaciers. All known failures occurred during peak melt
season, and the 2013 avalanche followed a large precipitation event.
Surprisingly, the failure originated in the least steep part of the
glaciated headwall. I will present some first results and observations from
a week long field investigation that we conducted in July 2018.

*Thursday, August 23rd**, 2018*
*10-11*
*am*
*  (Mountain Time)*
*USGS, 1711 Illinois Street, Golden, CO*
*Entry Level Seminar Room (204)*

*Note: Please arrive *~5 minutes early* and *bring photo ID* for
airport-style security measures now in place at the USGS building.

Thank you,
GHSC Seminar Committee

Mirus, Ben - bbmirus at usgs.gov
Josh Rigler - erigler at usgs.gov
Oliver Boyd - olboyd at usgs.gov <oboyd at usgs.gov>

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