Stress, Strain and Earthquakes:
The Tectonic Evolution of North America
What causes earthquakes? What forces are responsible for the
uplift of mountains? Why is the land subsiding in other regions? Why are
the continents adrift? What moves the continents and how do we know they
are moving? Answers to some of these simple questions have come through
decades of concentrated research involving multidisciplinary approaches.
The fields of earthquake seismology, space geodesy, mathematical
geophysics, and geochemistry have revealed exciting new insights into
the forces and processes that shape the land. I will focus on a
discussion of what we have learned about the tectonic forces and
processes that have influenced the evolution of North America. These
forces are in operation today. New discoveries about these tectonic
forces and processes have relevance to an increased understanding of
earthquake and volcanic hazards. Yet many more questions about large and
small scale tectonic processes remain unanswered. Because of this, like
most areas within the earth sciences, the field of geophysics has a rich
future.
Prof. Holt has served on numerous national and international
panels and was one of the founders of UNAVCO,
Inc., a non-profit organization that provides equipment support for
global positioning system research related to measuring tectonic
movements.
In 1995 Professor Holt was awarded the prestigious National
Science Foundation Career Award.
Prof.
Lianxing Wen
Department
of Geosciences
Journey to the center of the Earth from Seismology
As they travel through the Earth, earthquake
waves are influenced by the seismic properties (velocity, attenuation,
density) of the Earth's interior. The character of earthquake waves is
used to infer, even to great depths, the chemical composition and
mineralogy inside the Earth. In essence, earthquake waves open a window
for us to look "directly" inside the Earth. As a result, the
major discoveries related to the Earth's interior (crust, mantle, core)
have come from seismology, the study of earthquake waves. Prof. Wen will
discuss a recent discovery of differences in seismic wave speed and
attenuation in the inner core suggesting large scale anomalies. These
anomalies may be due to different alignments of iron crystals or
different proportions of melt inclusions in the eastern and western
hemispheres of the inner core.
Prof.
Lianxing Wen is an assistant professor of Geophysics, at the Department
of Geosciences, State University of New York at Stony Brook. His
research interests focus on seismology and geodynamics, the study of
physical processes inside the Earth
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