Most
everyone has heard about the San Andreas Fault, but have you heard about any of
the earthquakes, minor and major, that occur in the surrounding area? Ever wondered what is making the earthquakes
happen and whether these reasons are natural or human made from activities such
as drilling and hydraulic fraccing?
Earthquakes catch people’s attention whether it is from the fascination
of wondering what one feels like or whether it’s from personal experience being
in one.
Jeanne L. Hardebeck and Egill Hauksson wrote a report on the reasons earthquakes occur near faults from repeated strain related fracturing and crack sealing that
causes fluids to be trapped within low permeability barriers in the rock. The fluids trapped within a zone in the rock
create high fluid pressure that cannot be released from the low permeability
barriers. The high fluid pressures cause
the major stresses in the rock to rotate and change angles which can eventually
increase the fault and/ or cause an earthquake from localized strain
accumulation.
The Angle
Change of Major Stresses According to Distance from the Fault
Testing has
been done both in the field and in the lab to come to the conclusion that the
high fluid pressures with strain accumulation and change in stress angles can
cause the fault. So how is this relating
to the petroleum industry and hydraulic fraccing? There have been elevated fluid pressures
found near the San Andreas Fault during a drilling project close to the
site. The report shows no evidence of
clear blame on the drilling sites, but people will assume this is true based on
that statement.
Drilling and
hydraulic fraccing without regulations can cause major faults and earthquakes
to occur, but many regulations are in place with more being added as technology
improves. One regulation that protects
people in the surrounding area is that drilling cannot occur within a certain
distance of any residence with the distance being different based on the size
of the drilling project. For hydraulic
fraccing the Environmental Protection Authority (EPA) has a regulation that makes all projects stay at least two kilometers away from any town site and 500
meters from an environmentally sensitive site.
With these regulations, along with increasing technology, hydraulic
fraccing is a safe process that should not propose any problems with
earthquakes to any residence.
- Adam
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