March 2015 –TULSA, OK–
(Reuters) - Fault lines dating back hundreds of millions of years in
Oklahoma that have been recently reactivated could lead to a devastating
quake in the state where many structures were not built to withstand
major seismic activity, a report said. The state, which has seen several
hundred seismic events over the past five years, has “a high degree of
potential earthquake hazards,” according to the study accepted for
publication this month whose authors include researchers from the U.S.
Geological Survey (USGS). “The majority of the recent earthquakes in
central Oklahoma define reactivated ancient faults at shallow depths in
the crust” of less than 3.7 miles (6 km), said the report for the
American Geophysical Union.
The
report did not look at whether the reactivation of the faults was
linked to the energy extraction technique known as hydraulic fracturing,
or fracking. Daniel McNamara, one of the paper's authors and a research
geophysicist at USGS, said on Tuesday the 300 million-year-old
subsurface faults that had not been active are suspected to be
associated with the recent seismic activity. “Any one of these fault
zones that are producing magnitude 3 or 4 earthquakes could rupture into
a larger earthquake. There are as many as 12 different fault zones that
are capable of producing a large, 5 to 6 magnitude earthquake,” he
said. In November 2011, Oklahoma suffered a 5.6 magnitude quake that
damaged more than a dozen homes and several businesses.
Building
codes in Oklahoma for seismic events are not as stringent as in
quake-prone states such as California. Wastewater disposal related to
the fracking is suspected by many scientists to contribute to the
earthquake activity. Millions of gallons of wastewater are typically
trucked from a fracking site to wells where the water is injected
thousands of feet underground into porous rock layers. Energy companies
deny there is a link between fracking and major seismic activity. –Yahoo News
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