Induced Earthquakes

Induced Earthquakes

Induced Earthquakes

Although it has long been known that some forms of underground fluid injection can
increase the risk of earthquakes,21 the long-term impacts of extensive hydraulic
fracturing upon the risk of earthquakes in the Northeastern U.S. remains poorly

understood. In contrast, some information regarding short-term risks above the
Marcellus and Utica shale plays has become available.
Holland (2014) described one of the first observed cases in Oklahoma of earthquakes
triggered by the hydraulic fracturing phase (rather than underground wastewater
injection). The earthquakes were large enough to be felt by local residents.
In Maxwell’s (2013) description of an approach to evaluating HVHF-related seismic
events, criteria for confirming events, and existing injection and HVHF seismicity
protocols, the author described several seismic events ranging from low to moderate
energy. According to the author, during April and May of 2011 hydraulic fracturing near
Preese Hall, UK, resulted in an event with magnitude ML=2.3 (local magnitude scale)
and later another ML=1.5. The author added that, between 2009 and 2011, 38
earthquakes including a ML=3.8 resulted from hydraulic fracturing in the Horn River
Basin shale gas reservoir in north-east British Columbia, Canada.
In 2014, the Ohio Department of Natural Resources (ODNR) announced new, stronger
permit conditions for drilling near faults or areas of past seismic activity.22 The new
policies were developed in response to seismic events in Poland Township (Mahoning
County) that the ODNR determined were probably connected to hydraulic fracturing
near a previously unknown “microfault.” Under the new rules, permits issued by ODNR
for horizontal drilling within three miles of a known fault or area of seismic activity
greater than a 2.0 magnitude require companies to install sensitive seismic monitors. If
those monitors detect a seismic event in excess of 1.0 magnitude, activities must pause
while the cause is investigated. If the investigation reveals a probable connection to the
hydraulic fracturing process, all well completion operations must be suspended. ODNR

says that it will develop new criteria and permit conditions for new applications in light of
this change in policy. The department will also review previously issued permits for
wells that have not been drilled.

Conclusions – Health and Environmental Literature

The science surrounding HVHF shale-gas development and public health risks is only
just beginning to emerge. Many of the published reports investigating environmental
and health implications of HVHF activities are preliminary or exploratory in nature. As a
result, the available science on HVHF currently is limited and largely suggests
hypotheses about potential impacts that need further evaluation. Health impacts that
have been reported to be potentially associated with exposure to HVHF activities
include a variety of acute or self-limiting signs and symptoms such as skin rash or
irritation, nausea or vomiting, abdominal pain, breathing difficulties or cough,
nosebleeds, anxiety/stress, headache, dizziness, eye irritation, and throat irritation.
Other outcomes that have been reported as potentially associated with HVHF exposure
include low birth weight and some congenital defects. Studies of environmental impacts
have documented sub-surface methane migration from well casings to groundwater and
methane leakage to the atmosphere from HVHF infrastructure. Other environmental
impacts including noise and dust from well pads and truck traffic, increased traffic
accident rates, inadequate wastewater treatment, and induced earthquakes have been
observed. The actual degree and extent of these environmental impacts, as well as the
extent to which they might contribute to adverse public health impacts are largely
unknown. Nevertheless, the existing studies raise substantial questions about whether
the public health risks of HVHF activities are sufficiently understood so that they can be
adequately managed.