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Magmatic
      Underpinnings of Fluid-Driven Seismicity: The Generation of Trapped,
High-Pressure CO2-H2O Reservoirs in the Deep Roots
of Active Volcanoes: Nicole Lautze


Project Title: Magmatic Underpinnings of Fluid-Driven Seismicity: The Generation of Trapped, High-Pressure CO2–H2O Reservoirs in the Deep Roots of Active Volcanoes
Mendenhall Fellow: Nicole Lautze, nlautze@soest.hawaii.edu
Duty Station: Menlo Park, CA
Start Date: January 22, 2007
Education: Ph.D. 2006, University of Hawaii Manoa, Geology and Geophysics
Research Advisors: Thomas Sisson, (650) 329-5247, tsisson@usgs.gov; Margaret Mangan, (650) 329-5738, mmangan@usgs.gov

Project Description: Using high temperature/pressure laboratory- and computer- based simulations, this project seeks to understand the mechanisms of magmatic volatile liberation and mobilization at deep- to mid- crustal levels.  Exciting new research has suggested an association between deep long-period earthquakes (DLPs) and movement of magmatic fluids, even identifying a link between such seismic activity and surface magmatic degassing (Hill and Prejean, 2005; Peterson and others, 2005) and eruption (Power and others, 2004). Yet, although all models for long period seismicity invoke the movement of magma and/or associated aqueous-rich fluids, the feasibility and process of fluid release in the deep crust (~10-50 km) is not well understood.

Thanks to recent expansion of seismic networks (for example, in the Aleutians since 1989; Power and others, 2004) and advances in microanalytical techniques (Wallace, 2005), a picture of the deep magmatic processes occurring at subduction arc systems has recently begun to emerge. Along the Alaskan Aluetian arc, DLPs cluster beneath many volcanic centers at depths of 10-45 km, regions from near to well below the brittle-ductile transition that are otherwise seismically quiet.  The DLPs are generally a sporadic member of background seismicity independent of specific eruptive events. However, a notable occurrence of DLP occurred within the 10 months preceding Shishaldin’s most recent eruption (from April 7 to mid-May 1999), and a steady increase in DLP peaked just after an eruption at Mount Spurr volcano (on September 16–17, 1992; Power and others, 2004). An increased rate of LP seismicity has also preceded eruptive activity at the volcanoes Redoubt (Chouetand others, 1994), Galeras (Gil Cruz and Chouet, 1997), El Chichon (Havskov and others, 1983) and Pinatubo (Harlow and others, 1996; all in Peterson and others, 2005).  Despite these examples highlighting a link between DLP and surface eruption, many questions regarding their temporal and spatial occurrence remain.  A basic question to address is why DLP sometimes occur without any surface magmatic manifestation, while some active volcanoes seem to lack DLP completely.  

 Via laboratory experiments and computer modeling this project will explore the nature of deep crustal degassing and fluid segregation at conditions representing the depths of DLPs.  The simulations will yield data such as, for example, the volume and flux of gas release from a crystallizing magma body under known conditions of composition, pressure and temperature.  Linking such data with geophysical, fluid‐dynamical and structural models will enable us to address questions such as:

Given that there is some evidence of link between DLP and surface volcanic activity, increased DLP may be one of the earliest volcanic precursors (Power and others, 2004).  Therefore, by shedding light on the specific link between DLP and deep degassing, the results of this study may ultimately provide useful in eruption forecasting.

References:

Chouet, B.A., 1996, Long-period volcano seismicity: its source and use in eruption forecasting: Nature, v. 380, p. 309–316.

Cruz, F. G., and Chouet, B.A., 1997, Long-period events, the most characteristic seismicity accompanying the emplacement and extrusion of a lava dome in Galeras Volcano, Colombia, in 1991: Journal of Volcanology and Geothermal Research, v. 77, p. 121–158.

Harlow, D.H., Power J.A., Laguerta, E., Ambubuyog, G., White, R.A., and Hoblitt, R.P., 1996, Precursory seismicity and forecasting of the June  15, 1991 eruption of Mount Pinatubo, Philippines, in   Newhall, C., and Punongbuyan, R., eds., Fire and mud: Eruptions and lahars of Mount Pinatubo, Philippines: Seattle, University of Washington Press, p. 285–204.

Havskov, J., De la Cruz-Reyna, S., Singh, S. K., Medina, F., and Gutierrez, C., 1983, Seismic activity related to the March-April, 1982 eruptions of  El Chichon Volcano, Chiapas, Mexico: Geophysical Research Letters, v. 10,p. 293–296.

Hill D., and Prejean, S., 2005, Magmatic unrest beneath Mammoth Mountain California: Journal of Volcanology and Geothermal Research, v. 146, p. 25–283.  

Petersen, T., Caplan-Auerbach, J., McNutt, S.R., in press, Sustained long-period seismicity at Shishaldin Volcano: Alaska, Journal of Volcanology and Geothermal Research, v. 151, p. 365–381.

Power, J.A.,  Stihler, S.D.,White, R.A., and Moran, S.C., 2004, Observations of deep long-period (DLP) seismic events beneath Aleutian arc volcanoes; 1989–2002: Journal of Volcanology and Geothermal Research, v. 138, p. 243–266

 Wallace, P., 2005, Volatiles in subduction zone magmas: concentrations and fluxes based on melt inclusion and volcanic gas data: Journal of Volcanology and Geothermal Research, v.140, p. 217–240.


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