BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Granular research in extremes: from sand dunes in the desert to sn
 ow avalanches in the mountains
 - Nathalie Vriend (University of Cambrid
 ge)
DTSTART:20100202T130000Z
DTEND:20100202T140000Z
UID:TALK22710@talks.cam.ac.uk
CONTACT:Dr Geoffroy Lesur
DESCRIPTION:The transport of a granular material down an incline under the
  action of gravity is an example of a geophysical mass flow. These geophys
 ical mass flows occur in a variety of forms on Earth\, ranging from churni
 ng debris flow (Mt. St. Helens in 1980) to snow avalanches (Flateyri\, Ice
 land\, 1995) and from pyroclastic flows (Mount Unzen\, Japan\, 1991) to un
 derwater slides causing tsunamis (Cumbre Vieja volcano\, Canary Islands). 
 \n\nIn this presentation I will highlight research done during my PhD at t
 he California Institute of Technology\, USA on Booming Sand Dunes and prov
 ide a sneak-peak of my postdoctoral research at the University of Cambridg
 e on Snow Avalanches. \n
“Booming” sand dunes are able to produce a 
 persistent\, low-frequency sound that resembles a pure note from a music i
 nstrument. The sound has a dominant audible frequency (70 - 105 Hz) and se
 veral higher harmonics that may be heard from distances far away. A natura
 l or induced avalanche from a slip face of the booming dune triggers an em
 ission that may last for several minutes. Quantitative field research at d
 unes found in the Mojave Desert and Death Valley National Park in Californ
 ia\, USA provides experimental data. \n\nSnow avalanches form a significan
 t hazard for communities and directly influence the environment\, infrastr
 ucture\, economy and tourism of a region. The knowledge on the fluid dynam
 ics of these unpredictable avalanches is poor because of limitations on me
 asuring the internal structure of a large-scale avalanche. Different flow 
 regimes (dense core\, saltation and suspension layer) are apparent with or
 ders of magnitude difference in density. A collaborative (Leeds\, UCL) new
  effort\, spear-headed by Dr. Jim McElwaine at Cambridge\, measures the ve
 locity distribution of the dense core with an advanced Doppler Radar Syste
 m. Field experiments are scheduled this winter at Vallée de la Sionne in 
 Switzerland. \n
LOCATION:MR14\, DAMTP\, Pav. F
END:VEVENT
END:VCALENDAR