Friday, 17 November 2017  


 

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DTM

Global and Regional Seismology
(Matthew J. Fouch, David E. James, Alan T. Linde, Diana C. Roman
I. Selwyn Sacks, Sean C. Solomon)

Studies of the Earth's elastic and anelastic structure, ranging from high-resolution three-dimensional array studies of the lithosphere to studies of the lateral heterogeneity of the core-mantle boundary. Other areas of research include the delineation of features associated with descending slabs near subduction zones, attenuation studies in the asthenosphere as a method of locating anomalously high temperature regions, upper-mantle heterogeneity and its relation to convection, and examination of the 660-km discontinuity. The study of seismicity in active regions (such as Venezuela and Japan) is also pursued. Another major focus is the study of seismic anisotropy of the Earth's mantle. This is an excellent tool for the study of subcontinental mantle deformation associated with orogenies past and present, and for the mapping of flow in the convecting mantle. The ultimate goal of nearly all these programs is an understanding of the dynamics, structure, and evolution of the Earth.

Another area of interest is the physics of the earthquake process, including studies of crustal deformation and "slow" earthquakes in the near field as well as general study of source kinematics using far-field data. The investigators are interested not only in shallow earthquakes but also in the underlying mechanisms of intermediate- and deep- focus seismic events. Additionally, by using deformation and other related data, departmental investigators work on the mechanisms of volcanic eruptions.

Instrumentation development and deployment has always been a strength at DTM. The Department played a lead role in the design of a new broadband seismometer for use in conjunction with the national program in lithospheric seismology. The Department currently owns 25 broadband portable digital seismographs.

DTM possesses unique data sets for innovative studies in seismology. These seismographs have been deployed (together with others belonging to the national pool - PASSCAL - and to collaborators) in large-scale short-term deployments in southern Africa and, most recently, in the western United States in the High Lava Plains (HLP) project.  DTM scientists have deployed Sacks-Evertson strainmeters (single component dilatometers and three-component instruments) in Iceland, Japan, Peru, China, Italy, Greece, Taiwan, Montserrat, Hawaii, and along the San Andreas fault (California). These instruments, broadband with high dynamic range, are sensitive to seismic waves,  but they also detect slower deformations. They are thus ideal for studying crustal deformation and the earthquake process. Data from these instruments have been invaluable in studying slow earthquakes and volcanic activity.  The strainmeters are designed and constructed at DTM.  The lab also has an extensive library of data from standard global digital networks.

Volcanology and Microseismology

(Diana C. Roman)

I work to understand, from a mechanical perspective, the formation, structure, evolution, and dynamics of volcanic conduit systems and the source mechanisms and causes of microearthquake swarms occurring in the vicinity of active volcanoes. These two lines of research are tied together through development of conceptual, numerical, and analog models of the interaction of tectonic and volcanic processes. Although the majority of my work to date has focused on microearthquake swarms occurring in close spatial or temporal proximity to an erupting volcano, I have recently begun to apply the tools and techniques developed in volcano-seismic investigations to studies of tectonic microearthquake swarms and microseismicity associated with glacier dynamics.

Laboratory Studies
(I. Selwyn Sacks)

A laboratory program for studying the seismic properties of rocks, undertaken jointly with the Geophysical Laboratory. The group seeks to answer such questions as the relation between attenuation of seismic waves and the degree of partial melting of rocks appropriate for the mantle. Other areas of interest include the relation between phase transitions and deep-focus earthquakes, the nature of the 660-km discontinuity, the D" region at the base of the mantle, and the characteristics of strain-induced anisotropy in upper and lower mantle materials.

Planetary Evolution
(Sean C. Solomon, on
leave of absence)

Planetary Physics (graphics by Jan Dunlap) Geological, geophysical, and geochemical studies of magnetism, tectonics, and chemical evolution of the terrestrial planets. Tools include imaging and other experimental observations from recent spacecraft missions to the planets. Topics of current research include the history and resurfacing and outgassing on Venus, the nature and evolution of the lithosphere on Venus and Mars, the formation and structural and magmatic evolution of large volcanoes on the terrestrial planets, the nature of mantle-lithosphere interaction on Venus, and an exploration of the factors affecting differences in the tectonic evolution of Venus and Earth. This work is linked strongly to the research on solar system formation and to the broad efforts of the Department to understand the formation and evolution of the planet most accessible to detailed investigation--the Earth.

Postdoctoral Fellows and Associates

Paul Byrne

Kelsey Druken

Christian Klimczak

Ryan Porter

Deborah Smith

Christelle Wauthier

Predoctoral Fellows

 

Visiting Investigators

Satoshi Inaba