Delineation and Fine-Scale Structure of Active Fault Zones during the
2014-2023 unrest at the Campi Flegrei Caldera (Southern Italy) from
High-Precision Earthquake Locations
Abstract
In the past two decades, the central portion of Campi Flegrei caldera
has experienced ground uplift of up to 15 mm/month, and a consequent
increase in the rate, magnitudes and extent of seismicity, especially in
the past two years. We use a new method for multi-scale precise
earthquake location to relocate the 2014-2023 seismicity and map in
detail currently activated fault zones. We relate the geometry, extent,
and depth of these zones with available structural reconstructions of
the caldera. The current seismicity is mainly driven by the
time-varying, ground-uplift induced stress concentration on
pre-existing, weaker fault zones, not only related to the inner caldera,
dome resurgence but also to ancient volcano-tectonic collapses and magma
emplacement processes. The extent of imaged fault segments suggests they
can accommodate ruptures up to magnitude 5.0, significantly increasing
estimates of seismic hazard in the area.