JUSTIN REVENAUGH
Professor and Director of Graduate Studies
PhD, 1989, Massachusetts Institute of Technology
Research Group Web Page: Seismology, Geostatistics, and Geophysics
Office: 211 Pillsbury Hall
Phone: (612) 624-7553
Fax: (612) 625-3819
Email: justinr@...
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Research Interests
"And the Lord said unto Satan, Whence comest
thou? Then Satan answered the Lord, and said, From going
to and fro in the Earth, and from walking up and down in it."
Book of Job, 1:7
I've always been vaguely amused that
Satan, a character long associated with forbidden knowledge,
spends his days in the deep Earth?my primary area of interest.
As a seismologist, I use earthquake waves to image deep Earth
structure. My tools are derived from techniques pioneered
in the oil industry and designed to detect and characterize
abrupt variations in material properties, examples of which
include discontinuities associated with phase changes, scatterers
created by faulting and jointing of the crust, and slab dregs
near the core-mantle boundary. By imaging these small-scale
structures, we learn about the larger questions of Earthís composition,
state and dynamics.
Some of the projects I am involved with
are: the relationship between near-fault crustal scattering
and seismogenesis, characterization of sub-cratonic reflectors,
a search for discontinuities in the mid-mantle (900 to 2000
km depth), and probing for ultra-low velocity zones at the base
of the mantle. In the following, I briefly describe the
first and last of these.
Continental crust, especially crust in active
areas, is strongly scattering. Seismic energy propagating
through it interacts with strong heterogeneities on many scale
lengths, producing a panoply of secondary arrivals that collectively
sample a large volume around the source and receiver. We have
developed new techniques for mapping scattering heterogeneities.
Our results reveal a previously unknown relationship between
scattering and seismogenesis in California. In particular,
we find strong correlations between near-fault scattering strength
and the production of aftershocks and mainshock slip.
We have even used the offset in scattering variability across
the San Andreas fault to obtain an independent estimate of cumulative
offset in central California.
The crust is clearly a pivotal layer in
Earth's dynamics and evolution despite being eggshell thin and
patchwork woven. In the last decade, seismology has found
a deep-seated analog to the crust: A chemical and mechanical
boundary layer, comparable in thickness to the crust and possibly
in its importance to the evolution of the planet, situated directly
atop the core-mantle boundary (CMB). This thin layer (1
to 20 km) of very low seismic velocities is probably partially
molten and possibly chemically differentiated from the mantle,
and may be a shaper of the geodynamo and a storehouse for deep
mantle volatiles and exotic chemistry. My students and I exploit
a variety of seismic phases and seismic arrays to image these
ultra-low velocity zones (ULVZ). They are not simple,
but rather variable at scale-lengths of several kilometers.
Mapping them thoroughly is hard, but critical to understanding
their origin and the roles they play in mantle and core dynamics.
We have proposed a causal link between ULVZ and hotspot plumes.
If this hypothesis is correct, ULVZ might be the origin of plumes
that initiate supercontinent breakup, whose heads produce flood
basalts, and whose legacy in the geologic record includes both
mass extinctions and species explosions.
In addition to seismology, I have active
interests in time-series analysis of paleoclimate proxies, geostatistics
and coastal processes.
Selected Publications
- Rost, S., and J. Revenaugh, Seismic Detection of Rigid Zones at the Top of the Core, Science, 294, 1911-1914, 2001.
- Adams, P.N, R.S. Anderson, and J. Revenaugh, Microseismic measurement of wave- energy delivery to a rocky coast, Geology, 30, 895-898, 2002.
- Rost, S., and J. Revenaugh, Small-scale ultra-low velocity zone structure resolved by ScP, J. Geophys. Res., 108, 10.1028/2001JB001627, 2003.
- Bell, J.L., Sloan, L.C., Revenaugh, J., Duffy, P.B.: Evaluation of Northern Hemisphere natural climate variability in multiple temperature reconstructions and global climate model simulations. Global and Planetary Change, 37, doi: 10.1016/S0921-8181(02)000189-3, 2003.
- Bowen, G.J. and J. Revenaugh, Interpolating the isotopic composition of modern meteoric precipitation, Water Resources Research, 39, 1299, doi:10.129/2003WR002086, 2003.
- Rost, S., and J. Revenaugh, Detection of a D" discontinuity in the south Atlantic using PKKP, Geophys. Res. Lett., 30(16), 1840, doi:10.1029/2003GL017585, 2003.
- S. Rost and J. Revenaugh, Small-scale changes of core-mantle boundary reflectivity studied using core reflected PcP, Phys. Earth Planet. Int., 145, 19-36, 2004.
- Frederiksen, A.W., and J. Revenaugh, Lithospheric imaging via teleseismic scattering tomography, Geophys. J. Int., 159, 978-990, 2004.
- Williams, Q. and J. Revenaugh, Ancient subduction, mantle eclogite and the 300 km seismic discontinuity, Geology, 33, 1-4, 2005.
- Dykoski, C., R. L. Edwards, H. Cheng, D.Yuan, Y. Cai, M. Zhang, Y. Lin, J. Qing, Z. An, and J. Revenaugh, A high-resolution, absolute-dated Holocene and deglacial Asian monsoon record from Dongge Cave, China, EPSL, 233, 71-86, 2005.
Recent Research Support
- NSF: Short Period and Broadband Seismic Investigation of
the Core-Mantle Boundary and D"
- NSF: Collaborative Investigation of the Core-Mantle Boundary
- NSF: Northwestern Canada Seismic Experiment
- NSF: Scattered-Wave Imaging Algorithms for Regional and
Local Arrays
- NSF: The Role of Orbital Forcing in Periodic and Non-Periodic
Climate Change During the Oligocene and Early and Middle Miocene
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