Geologists and
seismologists
generally agree
that earthquakes
produce
dislocations
known as faults
and that
preexisting
faults tend to
localize new
earthquakes.
The bedrock of
New York City,
always
considered to be
solid and
impervious to
seismic
activity, is cut
by a great
number of
brittle faults
which belong to
two contrasting
sets oriented NE
and NW. These
faults dissect
the New York
City area into
large
fault-bounded
blocks. A “bone
of contention”
among
seismologists
and geologists
revolves around
a perceived lack
of evidence that
surface ground
breaks have
accompanied
historic bedrock
faulting. Many
seismologists
argue that the
faults that
structural
geologists map
in the field
experienced
offset at great
depth with no
surface
connection and
that uplift and
erosion have
unroofed these
structures to
the surface.
New research
from the Queens
Tunnel and the
Bronx provides
the first
demonstration of
surface
deformation in
response to
faulting in
geologically
recent
(postglacial)
time.
This research
provides the
first evidence
for surface
deformation in
response to
faulting in NYC
suggesting that
ground-breaking
rupture and
seismic activity
can not and
certainly should
not be ruled out
for this
region. Because
large magnitude
earthquakes have
struck NYC in
1737, 1783, and
1884, this new
data identifies
a potential
failure surface
along which
earthquake
energy could be
released. Given
the population,
cultural
development,
infrastructure,
and financial
investment
concentrated in
New York City,
the specter of a
massive
earthquake must
be considered in
revising
existing
building code
designs and
emergency
preparedness
procedures.
Unfortunately,
despite the
scientific
community’s
pleas for
action, severely
limited
emergency
planning exists
at the present
time. Clearly,
this should be
changed, as
pre-emptive
urban seismic
planning is an
absolute
necessity in New
York City.
