Steps Toward a “Best Practices” Protocol - Induced Seismicity Potential in Energy Technologies - page 130

embodied in any best practices protocol for induced seismicity can be complicated by the
challenges of determining whether any seismicity felt in a region with injection wells is
induced or is due to natural, geologic causes (see Chapter 1). However, we suggest that the
benefit of the collective dialogue and establishing best practices in the event of a felt seismic
event is in itself constructive, with few or no negative consequences.
EXISTING INDUCED SEISMICITY CHECKLISTS AND PROTOCOLS
Induced seismicity does not fall squarely in the sole purview of any single govern-
ment agency and, in fact, requires input and cooperation among several local, state, and
federal entities, as well as operators, researchers, and the public (see Chapter 4). Because
of these shared interests and potential responsibilities, the committee suggests that the
agency with authority to issue a new injection permit or the authority to revise an existing
injection permit is the most appropriate agency to oversee decisions made with respect to
induced seismic events, whether before, during, or after an event has occurred. In many
cases this responsibility would fall to state agencies that permit injection wells. In areas that
are known by experience to be susceptible to induced seismicity, a best practices protocol
could be incorporated into the approval process for any proposed (new) injection permit. In
areas where induced seismicity occurs, but was not anticipated in a particular area, existing
injection permits relevant to that area could be revised to include a best practices protocol.
Two Checklists to Evaluate the Potential for Induced Seismicity and the
Probable Cause of Observed Events
Checklists can be convenient tools for government authorities and operators to discuss
and assess the potential to trigger seismic events through injection, and to aid in determin-
ing if a seismic event is or was induced. Two checklists, one to address each of these two
circumstances—the potential for induced seismicity and the determination of the cause
of a felt event—were developed nearly two decades ago by Davis and Frohlich (1993) to
address each of these circumstances (summarized in the sections that follow). Their work
recommends a list of ten “yes” or “no” questions to quantify “whether a proposed injection
project is likely to induce a nearby earthquake” and a list of seven similar questions to
quantify “whether an ongoing injection project has induced an earthquake.”
W ill i injection. i nduce e arthquakes : t en -p oint c hecklist
The ten-question checklist evaluates four factors related to possible earthquake hazards:
historical background seismicity, local geology, the regional state of stress, and the nature
of the proposed injection. Table 6.1, modified from Davis and Frohlich (1993), compares