Modelling ground displacement and gravity changes

Modelling ground displacement and gravity changes
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Description

Campi Flegrei model This example demonstrates MUFITS capabilities for modelling the gravity changes and ground displacement. These options are applied in the 2-D axisymmetric study of magmatic gas flows during an unrest event at Campi Flegrei. This is a quite popular problem statement that formerly was considered by many authors. Here, we consider the problem statement most similar to that presented in Rinaldi et al. (2011). The problem includes an axisymmetric domain for modelling flows up to the depth of 1.5 km below the Solfatara crater. The influence of magma degassing is simulated with a point source of hot fluid placed at the depth of 1.5 km. We use the CO₂-H₂O mixture as a proxy for magmatic fluid. First, we simulate a dormant behaviour of the hydrothermal system over 4000 yr until a quasi-steady-state is reached. During that period, the flow rate of magmatic fluid is moderate. Then, an unrest event is simulated by increasing the flow rate over 20 months. Finally, the point source reverts to the dormant state and further 100 months are simulated. The unrest event results in the surface uplift and gravity changes that are simulated by the built-in capabilities of MUFITS.

Associated files

File	Version	Description
CAMPI-FLEGREI-2D.RUN	2020.B	Input file for the axisymmetric reservoir model of Campi Flegrei (shallow zone).
HM-STUDY.RUN	2020.B	Input file for a history matching study. This is the input file for Utilities program. The example demonstraites how the influx of magmatic fluid during the unrest event can be determined for a given observations of the gravity changes and ground displacement at Solfatara. The 3 files below are also needed to run this history matching study.
CAMPI-FLEGREI-2D.TEMPLATE	2020.B	The template of the RUN-file for modelling the hydrothermal activity at Campi Flegrei. The declaration $D#RATE is placed instead of a numerical value for the degassing rate. This parameter is varied by Utilities program to match the observations. The objective function is specified in the POST section of the template.
GRAVMTZ-OBS.TXT	2020.B	The include file containing the observations of the gravity changes over 120 month. The first column is time, and the second column is the gravity change at Solfatara.
UZ-OBS.TXT	2020.B	The include file containing the observations of the vertical ground displacement over 120 month. The first column is time, and the second column is the displacement at Solfatara.