The Acropolitan - v. 8, no. 5

In this issue...Dr. A. E. Koenig, Magma Yearbook, Montana School of Mines Museum, M whitewash, Commencement, Anderson-Carlisle Technical Society, Gamer's Cafe

The Amplifier - v. 3, no. 4

In this issue...Dr. Van Pelt, Anderson-Carlisle Society, Rose Garden Party, Main Hall, Gordon Parker, Magma Yearbook, Berkley Open Pit, Malmstrom Air Force Base

The Amplifier - v. 8, no. 6

In this issue...Sylvia White, Speed Skating, President Kennedy, St. John's Church, Mineral Club, Magma Yearbook, Honor roll, Montana Power Company

The Amplifier - v. 8, no. 7

In this issue...Magma Yearbook, Marvin Senne, Continental Oil Company, NASA, Circle K Club, Mine Rescue training, Walter Mitty, International Club, Stu Stadler

The Amplifier - v. 8,(a-10) no. 10

In this issue...Library, Constitution, fraternities, Continental Oil Company, Circle K Club, Mineral Club, Ed Simonich, Geologists, Montana Power Company, hayride party

The Amplifier - v. 12, no. 3

In this issue...Business Management, US Geological Survey, Finlen Hotel, Magma Yearbook, Copper Guard, Somewhere Else Coffee House, Marcus Daly Statue

The Amplifier - v. 13, no. 1

In this issue...Homecoming, Intramural Football, Cheerleaders, Poetry, Yellowstone Park, Snowflake-Springs, Karst Ranch, Butte Symphony, Surveying

The Amplifier - v. 13, no. 2

In this issue...Faculty Women's Club, Miss Montana, Mining Museum, Climbing Club, NASA, Butte Civic Center, Oredigger Football, Mrs. Loretta Peck, Library Remodel

The Amplifier - v. 14, no. 11

In this issue...Copper Guards, International Club, Magma Yearbook, Astrophysics, Roger Pierce, Ed Simonich, Mike Mansfield, M Club, Income Tax, Biology Department

Magma 1975

In this issue...Honors Convocation, Students, M Days, M Day Smoker, Sports, Montana Bureau of Mines and Geology, Awards, Cheerleaders

Magma 1970

In this issue...Tech After Hours, Students, Sports, Fraternities, Student Wives, Concerts, E Days, M Days, President Koch, Student Council

Magma 1995

In this issue...Graduates, M-Days, Sports, Clubs, Students, Faculty, Student Life, Mining Team, Intramurals

Magma 1965

In this issue...Engineers' Creed, Alumni Stadium, Library, Graduates, Sports, Prom, Hootenany, M Day, Clubs, Boosters, Students

Magma 1960

In this issue...Faculty, Graduates, Magma Staff, Hall Council, E Day, M Day, Sports, Orediggers, Around Campus, Boosters, Student Life

Magma Flow Instabilities in a Volcanic Conduit: Implications for Long-Period Seismicity

Silicic volcanic eruptions are typically accompanied by repetitive Long-Period (LP) seismicity that originates from a small region of the upper conduit. These signals have the capability to advance eruption prediction, since they commonly precede a change in the eruption vigour. Shear bands forming along the conduit wall, where the shear stresses are highest, have been linked to providing the seismic trigger. However, existing computational models are unable to generate shear bands at the depths where the LP signals originate using simple magma strength models. Presented here is a model in which the magma strength is determined from a constitutive relationship dependent upon crystallinity and pressure. This results in a depth-dependent magma strength, analogous to planetary lithospheres. Hence, in shallow highly-crystalline regions a macroscopically discontinuous brittle type of deformation will prevail, whilst in deeper crystal-poor regions there will be a macroscopically continuous plastic deformation mechanism. This will result in a depth where the brittle-ductile transition occurs, and here shear bands disconnected from the free-surface may develop. We utilize the Finite Element Method and use axi-symmetric coordinates to model magma flow as a viscoplastic material, simulating quasi-static shear bands along the walls of a volcanic conduit. Model results constrained to the Soufrière Hills Volcano, Montserrat, show the generation of two types of shear bands: upper-conduit shear bands that form between the free-surface to a few 100 metres below it and discrete shear bands that form at the depths where LP seismicity is measured to occur corresponding to the brittle-ductile transition and the plastic shear region. It is beyond the limitation of the model to simulate a seismic event, although the modelled viscosity within the discrete shear bands suggests a failure and healing cycle time that supports the observed LP seismicity repeat times. However, due to the paucity of data and large parameter space available these results can only be considered to be qualitative rather than quantitative at this stage.