Gas pipeline crosses newly discovered Arkansas fault
by Jon Gambrell
21-01-09
A previously unknown fault in eastern Arkansas could trigger a magnitude
7 earthquake with an epicentre near a major natural gas pipeline, a
scientist said. Haydar Al-Shukri, the director of the Arkansas Earthquake
Centre at the University of Arkansas at Little Rock, said the fault is
separate from the New Madrid fault responsible for a series of quakes in
1811-12 that caused the Mississippi River to flow backward.
Acres of cotton fields cover the fault west of Marianna, about 100 miles
east of Little Rock, but stretches of fine sand mixed with fertile soil gave
away the fault's location, Al-Shukri said. Liquefied sand bubbled up through
cracks in the earth, while ground radar and digs showed vents that let the
sand reach the surface, he said.
The fault, likely created in the last 5,000 years, sparked at least one
magnitude 7 earthquake in its history. Such temblors cause massive
destruction in their wake.
"This is a very, very dangerous (area) at risk of earthquake," Al-Shukri
said. "When you talk about (magnitude) 7 and plus, this is going to be a
major disaster." Al-Shukri did not identify a time frame for the potential
earthquake. Such a quake would affect Little Rock and neighbouring states
such as Tennessee and Mississippi, Al-Shukri said.
The researcher has said a gas pipeline crossed the newly discovered fault.
He declined to name the company that owned the pipeline. Al-Shukri had said
in a speech at the University of Arkansas' Clinton School of Public Service
that the company was building a large line through the area, mirroring the
old one's path.
A map made by the Arkansas Public Service Commission shows an Arkla Energy
Resources pipe in the area. A spokeswoman for CenterPoint Energy, which owns
Arkla, said that the company worked closely with public officials to prepare
response plans for earthquakes and other natural disasters.
Pipes are "all over the place," spokeswoman Rebecca Virden said. "We,
CenterPoint Energy, or someone else has a pipeline everywhere."
Carl Weimer, executive director of the Pipeline Safety Trust in Bellingham,
Washington, said companies with lines running through earthquake-prone
Southern California have extra safety features including "more valves and
different types of valves in case something happens and the pipeline can be
shut off quicker."
Clint Stephens, the chief of pipeline safety at the commission, said the
federal government would oversee any interstate lines.
Hundreds of earthquakes occur each year, including several in Arkansas. Most
Arkansas earthquakes occur in the state's northeast corner in the New Madrid
Seismic Zone, but Al-Shukri said the Marianna fault was not connected
because it was too far from the temblors caused by that zone.
During the winter of 1811 and 1812, a series of three earthquakes with
magnitudes of around 8 struck the zone and much smaller temblors continue to
hit today.
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