Mew Madrid Seismic Zone

1
Mew Madrid Seismic Zone Proposed Borehole
GeoObservatory Geologic Perspective
Robert D. Hatcher, Jr.
UT Distinguished Scientist and Professor Tectonics
and Structural Geology
Department of Earth and Planetary Sciences and
Science Alliance Center of Excellence
University of TennesseeKnoxville
Borehole GeoObservatory Workshop FEDEX Institute
of Technology University of Memphis May 3, 2007
2
World Earthquakes 19751995
Problem of large intraplate earthquakes
3
Regional Geology
From Reed et al., 2005, Geologic Map of North
America, GSA
4
Seismicity and Major Physiographic Features
From Schweig and Van Arsdale, 1996, Engineering
Geology
5
(No Transcript)
6
Bouguer Gravity
From Hildenbrand et al., 1995, USGS Prof. Paper
1538E
7
(No Transcript)
8
Aeromagnetic Data
From Hildenbrand et al., 1995, USGS Prof. Paper
1538E
9
First derivative reduced to pole magnetics
From Hildenbrand et al., 1995, USGS Prof. Paper
1538E
10
Interpreted Geology
From Hildenbrand et al., 1995, USGS Prof. Paper
1538E
11
Seismic Reflection Line Crowleys Ridge W
From Schweig and Van Arsdale, 1996, Engineering
Geology
12
Seismic Reflection Line Crowleys Ridge E
Growth faults
From Schweig and van Arsdale, 1996, Engineering
Geology
13
Seismicity and Major Features
From Schweig and Van Arsdale, 1996, Engineering
Geology
14
Neotectonics Tectonic Model
From Schweig and Van Arsdale, 1996, Engineering
Geology
15
Thoughts and Opinions
Seismicity and major surface geologic
features do not match well.
Seismicity more-or-less parallels the
subsurface early Paleozoic Reelfoot rift
(clearly reactived in the Eocene), but the
match is still not perfect.
Some correlations of seismicity exist with
very young features, recognized from
neotectonics studies.
Why arent more prominent rift in the
Mid-Continent (e.g., OK aulocogen,
Mid-Continent rift) seismically active?
Reactivated Paleozoic Reelfoot rift and other
hypotheses need reevaluation and refinement
with seismogenic zone borehole data.
16
Downhole (Structural) Geology Opportunities Part
ial List
Fault fabrics in seismogenic zone materials.
Fault and fracture timing and reactivation.
Role of fluids in modern and old faults.
Rheological behavior of different
lithologies/ rock units in the seismogenic
zone during faulting.
Build a more complete model for intraplate
seismicity.