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SUMMARY:Oscillations in stratified\, bubbly magma and long-period volcanic
  seismicity at Kilauea\, Hawaii AND The role of magmatic lithospheric thic
 kening on arc front migration - Leif Karlstrom\, University of Oregon
DTSTART:20151117T160000Z
DTEND:20151117T170000Z
UID:TALK60289@talks.cam.ac.uk
CONTACT:Alex Piotrowski
DESCRIPTION:The transport network by which magma leaves its mantle source 
 region and rises to the surface to erupt (or not) is hidden from direct ob
 servation\, and largely occurs on time and spatial scales that are outside
  the human experience. Our knowledge of magma transport pathways\, and the
  coupling of magmatism to other Earth systems\, is thus built on indirect 
 evidence. I will talk about two attempts to relate such evidence to subsur
 face magma dynamics.\n\nFirst I will discuss wave propagation within magma
 -filled conduits\, and the coupling of fluid oscillations to surrounding e
 lastic host rocks that may produce long period (10s of seconds) seismic si
 gnals observed at many active volcanoes. Specifically\, I will use seismic
 ity associated with ongoing rockfall events at Halemaumau\, Kilauea\, HI\,
  to study the excitation of resonant modes in a column of bubbly magma. I 
 will suggest that total magma volatile content and non-equilibrium degassi
 ng control conduit resonant modes\, and thus are imprinted on the periods 
 and decay rates of seismic signals.\n\nSecond\, I will discuss the focusin
 g of magmatism at convergent plate margins to a narrow band of volcanoes a
 t the surface\, and the spatial migration of this “arc front” over mil
 lions of years away from the plate interface. I will use a combination of 
 geochemical evidence and geodynamic modeling to suggest that arc front mig
 ration arises from magmatic lithospheric thickening\, modulated by tectoni
 c compression or extension within the upper plate.\n\nLeif Karlstrom and E
 ric M. Dunham Excitation and resonance of acoustic-gravity waves in a colu
 mn of stratied\, bubbly magma\, Under review\,JFM\n\nKarlstrom\, L.\, C.-
 T. A. Lee\, and M. Manga (2014)\, The role of\nmagmatically driven lithosp
 heric thickening on arc front migration\,\nGeochem. Geophys. Geosyst.\, 15
 \, 2655–2675\, doi:10.1002/2014GC005355.
LOCATION:Harker 1 seminar room\, Department of Earth Sciences
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