Skip to main content.

Smithsonian National Museum of Natural History

Department of Mineral Sciences

Izalco Volcano

Jan 15   Micro X-ray Fluorescence Imaging: Practical Applications and Analysis   Jeff Davis
Jan 22   No seminar    
Jan 29   Investigating the effect of mantle dynamics on Mercury's surface faults: Analysis of the distribution of tectonic features and crustal thickness   Michelle Selvans
Center for Earth and Planetary Studies, NASM
Jan 31 FRI
GeoPRISMs Distinguished Lecturer: Comparative Sedimentary Architecture of Magmatic versus Amagmatic Continental Rifts: Case Studies from East Africa   Chris Scholtz
Syracuse University
Feb 5   Making Evolved Melt Compositions on Asteroids   Kathryn Gardner-Vandy
Department of Mineral Sciences, NMNH
Feb 12   No seminar    
Feb 19   Multiview stereophotogrammetry: A practical field method for quantitative geomorphology

Multiview stereophotogrammetry: A practical field method for quantitative geomorphology

Stephen Scheidt
Center for Earth and Planetary Studies, NASM

Wednesday February 19, 10am

A digital camera and a notebook are the indispensable tools for the field geologist. However, these images are mostly anecdotal, secondary to hard data. By altering the process of image collection in the field, the images collected can be piped through algorithms that will automatically generate 3D data that can be used for quantitative analysis of geomorphology. For example, the rendered image shown on the seminar posters is a textured 3D model of a cinder cone at the vent of the McCartys lava flow in New Mexico. Only 12 aerial images taken from a consumer grade camera (by Jim Zimbelman) were used, whereas image catalogs with thousands of images are currently being used to reconstruct lava flow margins. By imaging features through time, it is possible to capture dynamic processes, such as active lava flows, sand dunes and fluvial systems.

Stephen Scheidt
Center for Earth and Planetary Studies, NASM
Feb 26   New experiments on the 3D structure of pyroclastic flows (including optional afternoon field trip to Experimental Volcanology Laboratory at the Museum Support Center)

New experiments on the 3D structure of pyroclastic flows

Ben Andrews
Department of Mineral Sciences, NMNH

Wednesday February 26, 10am

Pyroclastic density currents present substantial hazard to proximal populations. These currents transport and deposit volcanic material at high speed and can travel more than 10 km from the erupting vent. Such currents move because they are denser than the surrounding atmosphere. As they travel, however, they entrain and heat air, which often leads to buoyancy reversals and the generation of coignimbrite plumes; such plumes are responsible for dispersal of ash from Yellowstone-sized “super-eruptions.” Understanding how pyroclastic density currents mix with air is thus fundamental to predicting and interpreting their behavior. A recently constructed facility at the Museum Support Center permits, for the first time, the experimental study of unconfined density currents comprising turbulent suspensions of heated particles in air. These experiments are scaled such that they are dynamically similar to natural dilute pyroclastic density currents (e.g. pyroclastic surges). Illumination using three orthogonal laser sheets permits non-intrusive analysis of the 3-dimensional structure of the currents. Feature tracking velocimetry and time series analyses measure entrainment into the currents and quantify the timescales of mixing. These experiments show previous studies of confined currents fail to capture important entrainment processes through current margins, and that buoyancy reversal focuses current runout into a narrow dispersal axis.

Ben Andrews
Department of Mineral Sciences, NMNH
Mar 5   Contaminant biogeochemistry: Trace metal dynamics at the plant-soil interface   Carla Rosenfeld
Department of Mineral Sciences, NMNH
Mar 12   The Mogok Stone Tract, Myanmar: A geological update.   George Harlow
American Museum of Natural History
Mar 19   No seminar    
Mar 26   Sink to Survive: The persistence of ancient mountain belts through crustal density changes   Terry Blackburn
Carnegie Institution of Washington
Apr 2   Recent New Minerals from the Southwest   Joe Marty
Apr 9   TBA   Daniel Lathrop
University of Maryland
Apr 16   TBA    
Apr 23   TBA    
Apr 2   TBA    
Apr 30   TBA    
May 7   TBA   Lindy Elkins-Tanton
Carnegie Institution of Washington

[ TOP ]