In recent decades, finite-element modelling (FEM) has become a very popular tool in volcanological studies and has even been used to describe complex system geometries by accounting for multiple reservoirs, topography, and heterogeneous distribution of host rock mechanical properties. In spite of this, the influence of geological information on numerical simulations is still poorly considered. In this work, 2D FEM of the Colima Volcanic Complex (Mexico) is provided by using the Linear Static Analysis (LISA) software in order to investigate the stress field conditions with increasingly detailed geological data. By integrating the published geophysical, volcanological, and petrological data, we modelled the stress field considering either one or two magma chambers connected to the surface via dykes or isolated (not connected) in the elastic host rocks (considered homogeneous and non-homogeneous). We also introduced tectonic disturbance, considering the effects of direct faults bordering the Colima Rift and imposing an extensional far-field stress of 5 MPa. We ran the model using the gravity in calculations. Our results suggest that an appropriate set of geological data is of pivotal importance for obtaining reliable numerical outputs, which can be considered a proxy for natural systems. Beside and beyond the importance of geological data in FEM simulations, the model runs using the complex feeding system geometry and tectonics show how the present-day Colima volcanic system can be considered in equilibrium from a stress state point of view, in agreement with the long-lasting open conduit dynamics that have lasted since 1913.

Magmatism and tectonism are strongly related to regional and local stress fields, affecting both the orientation of faults and the location of volcanic vents

The Pleistocene–Holocene CVC is one of the most prominent volcanic edifices within the Trans-Mexican Volcanic Belt (TMVB) (

The eruptive history of the CVC started in the northeast area with the formation of the Cantaro volcano at ca. 1–1.5 Ma, followed by Nevado de Colima starting at ca. 0.53 Ma, which is composed of voluminous andesitic lava domes and deposits associated with caldera-forming eruptions and partial sector collapses

Seismic tomography

In this study, we used the commercial 8.0 version of LISA (

Element types used in LISA considering the final conduit feeding system configuration and the E–W cross section (

The stress field of the CVC plumbing system is simulated considering an E–W cross section, parallel to the extension associated with the active CR

Rock mass and mechanical properties of the geological units used in FEM from

Four units forming the CVC system were defined from the available geological data (Table 2): (i) a basement (Unit B) of Cretaceous limestones and intrusive rocks forming the bedrock underlying the CVC; (ii) graben fill deposits (Unit GF): Quaternary alluvial, colluvial, and lacustrine deposits filling the graben; (iii) Fuego de Colima deposits (Unit FC) of andesitic lavas and pyroclastic deposits forming the Paleofuego–Fuego de Colima edifices; and (iv) volcaniclastic deposits (Unit VD) covering the southern flank of the CVC

Results of the sensitivity analysis carried out on the Young modulus variations within each rock layer of the domain considering different configurations (stratified substratum model – nodes: 4426; single magma chamber model – nodes: 4426; dual magma chamber model – nodes: 4161; dual magma chamber model with conduits – nodes: 3737). For each geological unit (B, FC, GF, VD), the relative global variation in

Spatial variation (%) of the

In our 2D model, we assumed the CVC is composed of two magma chambers connected by dykes and to the surface by a conduit (Fig. 1d). The shape of the magma chambers and dykes is represented by elliptical cross sections with the major (

In this section we report the sensitivity analysis carried out to quantify the approximation of the Young modulus variation in FEM outputs and a description of the model outputs when adding complexity to the input geological–geophysical data.

Using the single magma chamber model as a reference case, we quantified the influence of Young modulus variation in each geological unit. Taking into account the mechanical properties of rocks (Table 2) as reference values, we compared the stress state of the computational domain on changing the Young modulus by (

E–W gravitational modelling of the CVC domain. The scale of the mesh is expressed in units of design (1 UD

In our case, the vector space

In Fig. 4 we report gravity-loaded models with homogeneous lithology composed of andesitic lavas (Fig. 4a) and non-homogeneous lithology composed of carbonates (Unit B) and alluvial, volcaniclastic, and pyroclastic deposits (Units GF and VD; Fig. 4b). It is important to stress that the

E–W gravitational modelling of the CVC domain with a non-homogeneous stratigraphy. The magnitude and pattern of the principal stresses are reported for

In Figs. 5 and 6 we show three cross-sectional profiles describing the feeding system starting from a single magma chamber to two chambers, then adding the conduits, and finally considering the full complexity by adding the effects of far-field stress and CR faults. Figure 5a describes the

E–W gravitational modelling of the CVC domain with a non-homogeneous stratigraphy accounting for a dual magma chamber system connected by dykes via the surface (deep magma chamber,

In order to explore the influence of the extensional far-field stress on stress patterns (Fig. 1a), we ran simulations applying 5 MPa (a typical low value for rift zones;

The effect of faults bordering the CR on the final feeding system configuration is simulated through two damage zones by degrading their elastic properties. Adding these elements does not significantly alter the stress distribution observed in Fig. 7v and vi but only provides a slight reduction in both

E–W gravitational modelling of the CVC domain with a non-homogeneous stratigraphy considering the extensional field stress. The magnitude and pattern of the principal stresses are shown for the single magma chamber model

The study highlights some important features of crustal stress distribution in terms of changing the geological and geophysical constraints used as input conditions

The results from the most complete FEM runs highlight an almost homogeneous stress distribution in the CVC area. This means the dual magma chamber model and the application of far-field stress provide a stable geometry, which limits the stress changes to a few megapascals (MPa). The majority of stress variations are located at the tips of the magma chambers, as expected for pressurized or under-pressurized cavities in the lithosphere

The presented study highlights the importance of using complete and detailed geological and geophysical data when dealing with FEM of volcanic areas. The different geological detail used in the model runs showed how the stress pattern critically depends on the geometry of the volcano feeding system, with huge differences in having a single or double magma chamber system and, in particular, whether or not the magma chamber(s) are connected to the surface by feeder dykes and conduits. The geometry of the feeding system is prevalent in model outputs with respect to varying rock properties (i.e. Young modulus) of 1 order of magnitude. In the case of CVC, the use of subsurface homogeneous or stratified lithology does not influence the FEM outputs much, with the subsurface geology of the computational domain being dominated by carbonates (Unit B). Beside and beyond the results obtained by analysing the influence of detailed geological and geophysical data, the presented modelling confirms the close-to-equilibrium state of the volcano, which is the expected stress distribution induced by a feeding system directly connected to the surface. The complete emptying of the upper conduit and part of the shallow magma chamber has in the past led to sub-Plinian and Plinian eruptions. This process permits the restoration of the stress arch and maintains a stable subsurface stress configuration. It follows that large-magnitude, caldera-forming eruptions are possible only if the bigger deep magma chamber is also involved and significantly emptied during an eruption.

The LISA code is available at

SM, RS, AC, GN, and GG conceived the study. SM and RS wrote the bulk of the paper with the input of all the co-authors. SM and GL compiled the numerical simulations and formulated the adopted methodology. MP and SM carried out the sensitivity analysis. RS, AC, SM, GN, GG, LC, GL, MP, and AG worked on the interpretation of the results.

The authors declare that they have no conflict of interest.

Silvia Massaro thanks LISA customer service for the support received.

The research leading to these results has received funding from the GEMex Project (to G. Norini), funded by the European Union's Horizon 2020 research and innovation programme under grant agreement no. 727550.

This paper was edited by Joachim Gottsmann and reviewed by Adelina Geyer and Virginie Pinel.