Geoscience Reference
In-Depth Information
BOX 1.1
Observations of Induced Seismicity
Seismicity induced by human activity has been observed and documented since at least the 1920s (Pratt
and Johnson, 1926). The number of sites where seismic events of
M
> 0 have occurred that are caused by or
likely related to energy development are listed below by technology. (References for these sites with location
and magnitude information are in Appendix C; note that in several cases the causal relationship between the
technology and the event was suspected but never confirmed.) The numbers of sites globally are listed first in the
column; the world map (Figure 1) shows these sites by technology and magnitude. The numbers in parentheses
are the numbers of sites, as a subset of the global totals, in which seismic events in the United States have been
caused by or likely related to energy development. In addition to energy technologies that are the topic of this
report, the list also shows induced seismicity due to surface water reservoirs (dams) and other activities related
to mining.
a
Event locations are plotted on global and U.S. maps in Figures 1 and 2.
Global (United States only)
Wastewater injection
11 (9)
Oil and gas extraction (withdrawal)
38 (20)
Secondary recovery (water flooding)
27 (18)
Geothermal energy
26 (4)
Hydraulic fracturing (shale gas)
2 (1)
Surface water reservoirs
44 (6)
Other (e.g., coal and solution mining)
8 (3
)
Total
156
Note that the figures include locations where a spatial association between seismicity and human activity
has suggested a causal relationship, but where a causal relationship has not been positively established. Indeed,
establishing such a causal relationship often requires a significant amount of scientific effort and fieldwork in
the form of temporary seismometer arrays, particularly for the remote locations at which underground activities
are conducted.
a
Mining operations can cause seismic events, in addition to the explosions that are used to fracture rock for excavation.
These seismic events may occur at shallow depths as a result of changes in crustal stress, both by removal of mining ore and by
redistribution of crustal stress from fracturing sound rock. Such events are not considered further in this report.
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