In the early evening on March 27, 1964 a magnitude 9.2 earthquake struck
beneath Alaska’s Prince William Sound, 75 miles east of Anchorage. The
ground shook for over four minutes, triggering landslides and a deadly
tsunami that claimed lives as far south as Crescent City, CA.
The Great
Alaska Earthquake was a devastating natural disaster that resulted in
over 100 deaths and hundreds of millions of dollars of damage. It is the
largest earthquake ever recorded in the United States, and the second
largest in the world.
Credit: U.S. Geological Survey/video by Stephen M. Wessells
As described
by the US Geological Survey (USGS), one positive development to emerge
from this tragedy was the huge advancement in our scientific
understanding of earthquakes. It is fitting then that tomorrow, on the
50th anniversary of this massive quake, the House Natural Resources
Committee is holding a hearing
on how earthquake science has advanced in that time. A better
understanding of the causes and consequences of earthquakes can help
reduce the risks to human life and property.
While major
breakthroughs in seismic research have been made in the 50 years since
the Great Alaska Earthquake, one topic about which more research is
urgently needed is induced seismicity. Unlike earthquakes caused by
natural movement in the earth’s crust, induced earthquakes are caused by
human activities, including mining, water reservoirs, and energy
production. As a result, they can take place in parts of the country not
traditionally thought of as earthquake territory.
In particular,
activities associated with oil and gas production have caused induced
earthquakes, including the underground injection of fluids like brine or carbon dioxide for disposal or enhanced oil recovery and – in a handful of cases – hydraulic fracturing. Most induced earthquakes caused by oil and gas activities have been relatively small but some, like the 2011 magnitude 5.7 earthquake in Oklahoma that was triggered by wastewater injection, are large enough to cause property damage and injuries.
Researchers
at the USGS found that the rate of earthquakes greater than magnitude
3.0 in the central and eastern United States has increased significantly
in the past decade, from an average of 21/year from 1967 through 2000
to more than 300 in the years 2010 through 2012, with 188 occurring in
2011 alone. The researchers hypothesize that this increase in activity
could be related to oil and gas production activities, including
underground injection of wastewater. This trend is particularly
troubling because the people, buildings, and emergency services in this
part of the country – states including Arkansas, Colorado, Ohio,
Oklahoma, and Texas – are less equipped to deal with seismic activity,
given that natural earthquakes are less frequent and cause less shaking.
As
this issue has gained national attention the pace of research has
increased, but there are still big gaps in our scientific knowledge and
more needs to be done. Resources need to be made available to academic
institutions and government agencies, like the USGS, that have the
technical abilities to research these complex issues. A better
understanding of induced seismicity can help scientists develop
strategies that could significantly reduce the chance that such
earthquakes will occur. Regulators have a role to play too, by requiring
the owners and operators of projects that have the potential to cause
earthquakes to:
- Perform induced seismic hazard and risk assessments;
- Submit these assessments as part of the permit application process;
- Monitor for earthquakes, and;
- Modify or stop activities if induced seismicity occurs.
If
there are places where the risks are too high and can't be mitigated,
activities that could cause induced seismicity should be prohibited.
Energy production must not come at the expense of public health and
safety.
The anniversary of the Great Alaska Earthquake is an
opportunity to focus not only on how far the science of earthquakes has
advanced, but also on what gaps remain and where to focus scientific
research now. We must continue to make breakthroughs in our
understanding of seismic activity, both natural and induced.
http://theenergycollective.com/brianamordick/359971/more-research-and-data-needed-induced-earthquakes-oil-and-gas-operations
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