Oregon State University

College of Earth, Ocean, and Atmospheric Sciences

Directory of People

Shanaka (Shan) de Silva

Shanaka de Silva photo
Discipline: Geology and Geophysics
Office: Wilkinson 216
Phone: 541-737-1212
Fax: 541-737-1200
Email: desilvas@geo.oregonstate.edu


Volcanology, Igneous Petrology, Aeolian sedimentology/geomorphology, Terrestrial Planetary Surface Processes

Research Interests

I am a field-based volcanologist with active interests in aeolian geomorphology and planetary analogs. The questions I address start in the field – there are so many interesting things we can see on the Earth…many of which we simply don't understand. Field observations are the starting point of my inquiry and these have led to some core themes in our research efforts: magmatism and volcanism in volcanic arcs, physical volcanology and petrology of explosive volcanic eruptions, effusion of crystal–rich lava, caldera (super)volcanism and the volcano-plutonic connection. To investigate these phenomena I use the volcanologists toolbox (Petrology, Geochemistry, Physical Volcanology, Geochronology, Remotely Sensed data, Geophysics) at all different scales. I am not an “expert” in any particular analytical technique, but I look for different tools and creative solutions for the problems of interest most often in collaboration with those who are experts. I like to think of this as "Volcano Forensics" - a CSI approach to volcanology.

Our research projects have taken us to Chile, Peru, Argentina, Bolivia, Italy, Indonesia, China, and Japan. Read about our work at Lake Toba, a large caldera in Sumatra.

As a volcanologist, why am I interested in aeolian geomorphology? While studying volcanic features in the high Andes, we couldn't ignore the fact that wind was producing an other-world landscape that was a valuable analog for the surface of Mars. Starting with yardangs, we have begun to address how the wind erodes and modifies high desert volcanic landscapes. Our latest work is trying to understand how gravel dominated bedforms form and rates of aeolian erosion of ignimbrite.

The broader impacts of our work relate to volcanic hazards, planetary surface processes, volcanism and climate, and Earth Science Education and Outreach (Visit our VolcanoWorld website). I am also committed to undergraduate research and Increasing Diversity in Earth Sciences.


B.Sc (Hons) Geology, University of Southampton, United Kingdom, 1982
PhD Earth Sciences, Open University, United Kingdom, 1987


GEO 495 – Field Camp (Summer 2016)
GEO 627 – Advanced Volcanology (Fall 2016)
GEO 201 – Physical Geology (Winter annually)
GEO 305 – Living with Active Cascade Volcanoes (Spring 2018)
GEO 499 – Surface Processes on the Terrestrial Planets (Spring 2018)
GEO 427 – Volcanology

Graduate Students

Current Graduate Students

  • Michelle Neely (BS Portland State, 2014) Pattern to Process: morphometry and process in gravel megaripples in the Puna of Argentina
  • Jade Bowers (BS U of Arizona, 2016) Sinabung Volcano, Sumatra; current eruptions and their relation to Toba
  • Katharine Solada (BS Miami of Ohio, 2015) Paleomagnetic correlation and timescale of resurgence at Toba, Sumatra

Recent Graduate Theses (Primary Advisor unless stated)

  • Adonara Mucek (PhD 2017) Resurgence at Toba Caldera, Sumatra
  • Bethany Murphy (MS 2015) Timescales of silicic magmatic processes: U-Series zircon chronochemistry of Mt Unzen, Japan
  • Stephanie Grocke (PhD 2014) Magma Dynamics and Evolution in Continental Arcs: Insights form the Central Andes
  • Dale Burns (PhD 2014) Crustal Architecture and Magma Dynamics in a Large Continental Magmatic System: A Case Study of the Purico-Chascon Volcanic Complex, Northern Chile (co-advised wth Frank Tepley)
  • Jason Kaiser (PhD 2014) Understanding Large Resurgent Calderas and Associated Magma Systems: The Pastos Grandes Caldera Complex, Southwest Bolivia
  • Jamie Kern (MS 2012) The plutonic record of the Altiplano Puna Volcanic Complex revealed by zircon chronology
  • Rodrigo Iriarte (MS 2012) The Cerro Guacha Caldera Complex, SW Bolivia: stratigraphy, volcanology, and magma dynamics
  • Claire McLeod (Ph.D 2012) Investigations of crustal contamination through petrology and geochemistry (U of Durham co-advised w/ Jon Davidson)
  • Casey Tierney (MS 2011) Timescales of silicic magmatic processes: U-Series chronochemistry of effusive domes of the Altiplano Puna Volcanic Complex.
  • Chris Folkes (Ph.D. 2011) Physical Volcanology and Magmatic evolution of the Cerro Galan Caldera Complex, NW Argentina. (Monash University, Co-advisor w/Ray Cas, Heather Wright)
  • Chris Harpel (Ph.D. 2010), Lahar sedimentology and hazards of the 2ka eruption of El Misti, southern Peru
  • Robert Peckyno (MS - 2010), Morphometric parameters of terrestrial lavas
  • Mangon Abot (MS - 2010), Amphibole-Plagioclase P-T estimates for the Altiplano Puna Volcanic Complex (Co-advisor with Anita Grunder)

Former Advisees and Co-Advisees – where are they now?

  • Adonara Mucek, Singapore, Earth Observatory of Singapore
  • Bethany Murphy, Engineering Geologist, Auckland, New Zealand
  • Stephanie Grocke, Iceland Volanological Survey, Fulbright Post Doctoral Fellow
  • Dale Burns, Stanford University, Research Faculty
  • Jason Kaiser, University of Southern Utah, Assistant Professor
  • Chris Folkes, Geological Survey of New South Wales, Geologist
  • Rodrigo Iriarte , Universidad Major San Andres, La Paz, Bolivia, Professor
  • Jamie Kern, Informal Educator, National Park Service
  • Claire McLeod, University of Miami of Ohio, Assistant Professor
  • Casey Tierney, PhD program, Northern Arizona University
  • Chris Harpel, VDAP, USGS, CVO Vancouver, WA
  • Robert Peckyno, Multimedia Consultant, Wellington, New Zealand
  • Mangon Abot, Malaysian Geological Survey, Program Head

Hosted/Sponsored Post docs / Research Visitors

  • Shimpei Uesawa (2017-2018) CRIEPI, Japan
  • Johan Varekamp (2017) Wesleyan University, CT, USA (Sabbatical Visit)
  • Seiko Yamasaki (2016-2017) Institute of Earthquake and Volcano Geology, Geological Survey of Japan
  • Akihiko Tomiya (2014-2015) Institute of Earthquake and Volcano Geology, Geological Survey of Japan
  • Bo Pan - (2013-2014) Chinese Earthquake Administration
  • Mauro Spagnuolo (2013 - 2014) - CONICET Research Fellow at Universidad Buenos Aires, Argentina


Papers from last 3 Years (Student authors identified with *; Post doc )


de Silva, S.L., Bailey, J.E., Some unique surface patterns on ignimbrites on Earth: A“bird's eye” view as a guide for planetary mappers, Journal of Volcanology and Geothermal Research. Available online 17 July, 2017. http://dx.doi.org/10.1016/j.jvolgeores.2017.06.009

Pan, B., de Silva, S.L., Xu, J., Chen, Z., Miggins, D.P., Wei,H., 2017. The VEI-7 Millennium eruption, Changbaishan-Tianchi volcano, China/DPRK: New field, petrological, and chemical constraints on stratigraphy, volcanology, and magma dynamics, Journal of Volcanology and Geothermal Research, Available online 7 June 2017, ISSN 0377-0273, https://doi.org/10.1016/j.jvolgeores.2017.05.029.

Godoy, B*., Wörner, G., Le Roux, P., de Silva, S.L., Parada, M.A., Kojima, S., González-Maurel, O., Morata, D., Polanco, E., Martínez, P., 2017. Sr- and Nd- isotope variations along the Pleistocene San Pedro – Linzor volcanic chain, N. Chile: Tracking the influence of the upper crustal Altiplano-Puna Magma Body, Journal of Volcanology and Geothermal Research, Available online 31 May 2017, ISSN 0377-0273, https://doi.org/10.1016/j.jvolgeores.2017.05.030.

Mucek, A. E*., Danisik, M., de Silva, S. L., Schmitt, A. K., Pratomo, I., & Coble, M. A. (2017). Post-supereruption recovery at Toba Caldera. Nature Communications, 8, 1-9. http://doi.org/10.1038/ncomms15248

Grocke, S. B*., de Silva, S. L., Iriarte, R.*, Lindsay, J. M., & Cottrell, E. (2017). Catastrophic Caldera-Forming (CCF) Monotonous Silicic Magma Reservoirs: Geochemical and Petrological Constraints on Heterogeneity, Magma Dynamics, and Eruption Dynamics of the 3·49 Ma Tara Supereruption, Guacha II Caldera, SW Bolivia. Journal of Petrology, 58(2), 227–260. http://doi.org/10.1093/petrology/egx012


Perkins, J. P.*, Ward, K. M., de Silva, S. L., Zandt, G., Beck, S.L., & Finnegan, N.J., (2016). Surface uplift in the Central Andes driven by growth of the Altiplano Puna Magma Body. Nature Communications, http://doi.org/10.1038/ncomms13185

Kaiser, J. F.*, de Silva, S., Schmitt, A. K., Economos, R., & Sunagua, M. (2016). Million-year melt–presence in monotonous intermediate magma for a volcanic– plutonic assemblage in the Central Andes: Contrasting histories of crystal-rich and crystal-poor super-sized silicic magmas. Earth and Planetary Science Letters, 1–14. http://doi.org/10.1016/j.epsl.2016.09.048

Tierney, C.R.*, Schmitt, A.K., Lovero, O.M., & de Silva, S.L., 2016. Voluminous plutonism during volcanic quiescence revealed by thermochemical modeling of zircon. Geology, 44, 683-686

Best. M., Christiansen, E.H., de Silva, S., & Lipman, P. W. (2016). Slab-rollback ignimbrite flareups in the southern Great Basin and other Cenozoic American arcs: A distinct style of arc volcanism. Geosphere, GES01285.1–39. http://doi.org/10.1130/GES01285.1

Kern, J. M.*, de Silva, S. L., Schmitt, A. K., Kaiser, J. F*., Iriarte, A. R.*, & Economos, R. (2016). Geochronological imaging of an episodically constructed subvolcanic batholith: U-Pb in zircon chronochemistry of the Altiplano-Puna Volcanic Complex of the Central Andes. Geosphere, GES01258.1–24. http://doi.org/10.1130/GES01258.1

Grocke, S. B.*, Cottrell, E., de Silva, S., & Kelley, K. A. (2016). The role of crustal and eruptive processes versus source variations in controlling the oxidation state of iron in Central Andean magmas. Earth and Planetary Science Letters, 440(C), 92–104. http://doi.org/10.1016/j.epsl.2016.01.026

Zimbelman, J. R., Scheidt, S. P., de Silva, S. L., Bridges, N. T., Spagnuolo, M. G., & Neely, E. M.* (2016). Aerodynamic roughness height for gravel-mantled megaripples, with implications for wind profiles near TARs on Mars. Icarus, 266(C), 306–314. http://doi.org/10.1016/j.icarus.2015.11.008


Gregg, P. M., Grosfils, E. B., & de Silva, S. L. (2015). Catastrophic caldera-forming eruptions II: The subordinate role of magma buoyancy as an eruption trigger. Journal of Volcanology and Geothermal Research, 305(C), 100–113. http://doi.org/10.1016/j.jvolgeores.2015.09.022

Perkins, J. P#., Finnegan, N. J., & de Silva, S. L. (2015). Amplification of bedrock canyon incision by wind. Nature Geoscience. doi:10.1038/ngeo2381

Bridges, N T, M G Spagnuolo, S L de Silva, J R Zimbelman, and E M Neely*. 2015. “Formation of Gravel-Mantled Megaripples on Earth and Mars: Insights From the Argentinean Puna and Wind Tunnel Experiments.” Aeolian Research 17 (C). Elsevier B.V.: 49–60. doi:10.1016/j.aeolia.2015.01.007.

de Silva, S. L., Mucek, A. E.#, Gregg, P. M., & Pratomo, I. (2015). Resurgent Toba—field, chronologic, and model constraints on time scales and mechanisms of resurgence at large calderas. Frontiers in Earth Science, 3. doi:10.3389/feart.2015.00025

Burns, D. H. #, de Silva, S. L., Tepley, F., III, Schmitt, A. K., & Loewen, M. W.# (2015). Earth and Planetary Science Letters. Earth and Planetary Science Letters, 422(C), 75–86. doi:10.1016/j.epsl.2015.04.002

de Silva, S. L., Riggs, N. R., & Barth, A. P. (2015). Quickening the Pulse: Fractal Tempos in Continental Arc Magmatism. Elements, 11(2), 113–118. doi:10.2113/gselements.11.2.113