Publication Date:
2021-05-12
Description:
Slip rate is a critical parameter for describing geologic and earthquake rates of known active faults. Although
faults are inherently three-dimensional surfaces, the paucity of data allows for estimating only the slip rate at
the ground surface and often only few values for an entire fault. These values are frequently assumed as proxies
or as some average of slip rate at depth. Evidence of geological offset and single earthquake displacement, as well
as mechanical requirements, show that fault slip varies significantly with depth. Slip rate should thus vary in a
presumably similar way, yet these variations are rarely considered.
In this work, we tackle the determination of slip rate depth distributions by applying the finite element method
on a 2D vertical section, with stratification and faults, across the central Apennines, Italy. In a first step, we perform
a plane-stress analysis assuming visco-elasto-plastic rheology and then search throughout a large range of
values to minimize the RMS deviation between the model and the interseismic GPS velocities. Using a parametric
analysis, we assess the accuracy of the best model and the sensitivity of its parameters. In a second step, we
unlock the faults and let the model simulate 10 kyr of deformation to estimate the fault long-term slip rates.
The overall average slip rate at depth is approximately 1.1 mm/yr for normal faults and 0.2 mm/yr for thrust
faults. A maximum value of about 2 mm/yr characterizes the Avezzano fault that caused the 1915, Mw 7.0 earthquake.
The slip rate depth distribution varies significantly from fault to fault and even between neighbouring
faults, with maxima and minima located at different depths. We found uniform distributions only occasionally.
We suggest that these findings can strongly influence the forecasting of cumulative earthquake depth distributions
based on long-term fault slip rates.
Description:
Project “Abruzzo” (code: RBAP10ZC8K_
003) funded by the Italian Ministry of Education, University and Research
(MIUR).
Description:
Published
Description:
1T. Geodinamica e interno della Terra
Description:
2T. Tettonica attiva
Description:
3T. Pericolosità sismica e contributo alla definizione del rischio
Description:
JCR Journal
Description:
restricted
Keywords:
slip rate
;
numerical model
;
fault
;
rheology
;
central Italy
;
active tectonics
;
04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations
;
04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology
;
04. Solid Earth::04.04. Geology::04.04.09. Structural geology
;
04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution
;
04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
;
04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics
;
04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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