- Created: Tuesday, 03 October 2017 10:35
Coos Bay, OR – Geology Lecture Series at Southwestern
Southwestern Oregon Community College’s popular Geology Lecture Series kicks off this year with Dr. Stephen McNutt, speaking about “Shaking and Baking: Using Seismology to Study Volcanoes” at 7 p.m., Saturday, October 21, 2017 at the Hales Center for Performing Arts.
Seismology is used to study volcanoes in several ways. Seismic tomography, similar to medical tomography, is used to probe beneath volcanoes for their velocity and attenuation structure. This reveals the size, shape and location of bodies of molten rock underground, such as magma chambers and conduits. Models have become more detailed over the years as techniques and data have improved.
One result of such studies is a model of the structure of the volcano. The model then provides a conceptual pathway to interpret the seismic activity that occurs prior to eruptions. A common pattern is an increase first in volcano-tectonic earthquakes caused by increasing pressure in the magma chamber communicated to faults in the rocks nearby. This is followed by low-frequency earthquakes, which are likely related to fluid processes involving magma or water and gases. Third, a continuous signal known as volcanic tremor occurs when magma reaches shallow levels near the vent. Explosions and strong eruption tremor are associated with the eruption. Deep earthquakes sometimes occur as stresses readjust after the removal of magma. Such patterns, together with understanding of physics, have enabled successful forecasts of eruptions over a range of sizes and types.
The strength and character of some eruption seismic signals also provides clues to make near-real time assessments of eruptions while they are in progress. For example, the strength of eruption tremor is proportional to the height of the ash column. Lava fountaining from fissures makes stronger tremor than fountaining of the same height from cylindrical conduits. Magma with more gases makes stronger seismic signals and more fine ash, which can influence the amount of volcanic lightning!
These are the types of questions that Professor McNutt will explore as he discusses how the movement of magma causes volcano shaking and baking.
Dr. McNutt is a professor and head of the Seismology Laboratory at the School of Geosciences, University of South Florida. His research focus is in the field of volcano geophysics, including seismology, infrasound and lightning. Dr. McNutt has studied more than 160 volcanic areas worldwide, and is particularly interested in volcanoes in Alaska and Central and South America. Professionally he served as Secretary General for the International Association of Volcanology and Chemistry of the Earth's Interior, has served on several committees for the National Academy of Sciences, including the US National Committee for International Union of Geodesy and Geophysics, the US National Committee for the Pacific Science Association, and the standing Committee on Seismology and Geodynamics. Steve earned his B.A. from Wesleyan University and his M.A. and Ph.D. from Columbia University. 1985
This Lectures Series. For over a decade, the IRIS/SSA lecture series has enabled world-renowned scientists to travel and speak to public audiences about cutting-edge earthquake research.
Geology Lecture Series talks are free and are held in the Hales Center for the Performing Arts on Southwestern’s Coos Campus, 1988 Newmark Ave., Coos Bay. For those not able to attend in person, all lectures are Livestreamed and archived, with access from the College's web site at www.socc.edu. Additional talks scheduled this year include: Dr. Roman Gomez (study of the Earth’s magnetic field) on December 2, 2017, Dr. Justin Rubenstein (human induced earthquakes) on January 26, 2018, Dr. Anne Nolin (changing climate) on March 3, 2018, Dr. David Montgomery (bringing soil back to life) on April 14, 2018 and Dr. Josh Roering (insight form geologic “accidents”) on May 19, 2018. Additional sponsors of this lecture include DB Western, the Southwestern Foundation and the College.
For additional information please contact Ron Metzger at 541-888-7216.