Abstract
Aftershock cascades play an important role in forecasting seismicity in
natural and human-made situations. While their behavior including the
spatial aftershock zone has been the focus of many studies in tectonic
settings, this is not the case when fluid flows are involved. Using
high-quality seismic catalogs, we probe earthquake-earthquake triggering
in three settings influenced by fluids: \emph{i}) A
natural swarm (Long Valley Caldera, California),
\emph{ii}) \emph{suspected} swarms in
the Yuha Desert (California), and \emph{iii}) induced
seismicity in Oklahoma and southern Kansas. All settings exhibit
significant aftershock behavior highlighting the importance of secondary
processes. The spatial aftershock zones scale with mainshock magnitude
as expected based on the rupture length. While
\emph{i}) and \emph{iii}) show a rapid
decay beyond their rupture length, \emph{ii}) exhibits
long-range behavior suggesting that fluid migration might not be the
dominant mechanism. We also find that aftershock productivity might
allow to distinguish between natural swarms and induced seismicity.