Publication Date:
2022-05-04
Description:
In northern Italy in 1997, two earthquakes of magnitudes 5.7 and
6 (separated by nine hours) marked the beginning of a sequence
that lasted more than 30 days, with thousands of aftershocks
including four additional events with magnitudes between 5 and
6. This normal-faulting sequence is not well explained with
models of elastic stress transfer1,2, particularly the persistence of
hanging-wall seismicity3 that included two events with magnitudes
greater than 5. Here we show that this sequence may have
been driven by a fluid pressure pulse generated from the coseismic
release of a known deep source4 of trapped high-pressure
carbon dioxide (CO2). We find a strong correlation between the
high-pressure front and the aftershock hypocentres over a twoweek
period, using precise hypocentre locations5 and a simple
model of nonlinear diffusion. The triggering amplitude (10–
20MPa) of the pressure pulse overwhelms the typical (0.1–
0.2MPa) range from stress changes in the usual stress triggering
models1,6. We propose that aftershocks of large earthquakes in
such geologic environments may be driven by the coseismic
release of trapped, high-pressure fluids propagating through
damaged zones created by the mainshock. This may provide a
link between earthquakes, aftershocks, crust/mantle degassing
and earthquake-triggered large-scale fluid flow.
Description:
Published
Description:
724-727
Description:
reserved
Keywords:
aftershock
;
CO2
;
04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
Format:
425100 bytes
Format:
application/pdf
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