MeltExtrusion
Initialization
Extruded material is defined using material types called "ExtrudedGabbroicMagma" (extruded lava) and "SolidifiedBasalt" (solidified lava). These two material types must be defined in the material model for the extrusion model to work. See Material Types for more information about material types.
The volume of extruded volcanic material is calculated as the product of the extrusion volume factor and the total incremental volume of magma produced within the mantle in a given migration domain.
The flow distance of individual lava flows is controlled by the residual lava thickness, total volume of the flow and surface relief. Lava flows will advance only after the residual lava thickness has been reached and a downward slope is present.
The characteristic volume of lava per flow is equal to the product of the characteristic flow length and the residual lava thickness, which have different values for subaerial and submarine flows. The total number of lava flows per time step is calculated as the total volume of magma produced in a particular migration domain divided by the characteristic volume of lava per flow. The flow distance of a given lava flow is directly proportional to the characteristic flow length and inversely proportional to the residual lava thickness.
The location of extrusion at the surface is controlled by the extrusion window. The center of the extrusion window is determined by x-coordinate of the shallowest partially molten mantle marker. If width_eruption_domain_fixed is zero then the width of the extrusion window is defined by the minimum and maximum x-coordinates of the partially molten or molten gabbroic material. With this model, extrusion is spatially related to gabbroic magma chambers and gabbroic magma mush zones (gabbro glacier). If width_eruption_domain_fixed is greater than zero, the width of the extrusion window is equal to the value of width_eruption_domain_fixed.
Two models are available for eruption location of a laval flow at the surface within the extrusion window:
- Probabilistic:
- The eruption location is chosen either randomly (
iuse_random_eruption_location = 1) or from a normal distribution (iuse_normal_eruption_location = 1) within the extrusion window.
- The eruption location is chosen either randomly (
- Static (
iuse_random_eruption_location = 0):- With this option the eruption location is fixed at the midpoint of the extrusion window.
The parameters porosity_initial_lava_flow and decay_depth_lava_flow are used to decompact extruded gabbroic magma to account for vesicles. Note that compaction during burial is not controlled by these parameters and is instead controlled by the material type.
EarthBox.MeltModel.Extrusion.initialize! — Function
initialize!(model::ModelData; kwargs...)::NothingInitialize melt extrusion model parameters.
Arguments
model::ModelData: The model data container containing the model parameters and arrays.
Keyword Arguments
iuse_extrusion::Int64- Integer flag that activates melt extrusion model: 0 off; 1 on
iuse_random_eruption_location::Int64- Integer flag that activates random eruption location: 0 off; 1 on
iuse_normal_eruption_location::Int64- Integer flag that activates normal distribution for eruption location: 0 off; 1 on
iuse_eruption_interval::Int64- Integer flag that activates eruption interval: 0 off; 1 on
extrusion_volume_factor::Float64- Minimum value for the extrusion volume factor. The volume of lava produced at the surface of the model is calculated as the product of the extrusion volume factor and the total volume of magma produced during a time step. The extrusion volume factor changes as a function of the characteristic magmatic crust height. The characteristic magmatic crust height is the height of new crust that would be formed if all the melt in the mantle was extracted and emplaced at the top of the model in a column with a width equal to the full extension velocity times the time step. This minimum value is used when the magmatic crust height is below the minimum characteristic magmatic crust height. A linear model is used to define the extrusion volume factor when the calculated magmatic crust height is between the minimum and maximum characteristic magmatic crust height.
extrusion_volume_factor_max::Float64- Maximum value for the extrusion volume factor. This maximum value is reached when the characteristic magmatic crust height is equal to the maximum characteristic magmatic crust height.
characteristic_magmatic_crust_height_min::Float64- Minimum reference value for the characteristic magmatic crust height in meters. When the calculated characteristic magmatic crust height is below this value the extrusion volume factor is set to the minimum value (i.e.
extrusion_volume_factor).
- Minimum reference value for the characteristic magmatic crust height in meters. When the calculated characteristic magmatic crust height is below this value the extrusion volume factor is set to the minimum value (i.e.
characteristic_magmatic_crust_height_max::Float64- Maximum reference value for the characteristic magmatic crust height in meters. When the calculated characteristic magmatic crust height is above this value the extrusion volume factor is set to the maximum value (i.e.
extrusion_volume_factor_max).
- Maximum reference value for the characteristic magmatic crust height in meters. When the calculated characteristic magmatic crust height is above this value the extrusion volume factor is set to the maximum value (i.e.
width_eruption_domain_fixed::Float64- Fixed width of the eruption domain in meters. If this is set to zero, the width of the eruption domain is determined by the width of the gabbroic molten zone including normal and layered gabbro.
width_eruption_domain_fixed_max::Float64- Maximum width of the eruption domain. If this is set to zero, the width of the eruption domain is determined by the width of the gabbroic molten zone including normal and layered gabbro.
residual_lava_thickness_subaerial::Float64- Residual lava thickness for subaerial eruptions in meters
characteristic_flow_length_submarine::Float64- Characteristic flow length for submarine eruptions in meters.
characteristic_flow_length_subaerial::Float64- Characteristic flow length for subaerial eruptions in meters. Flow distance of basaltic flows on land may be hundreds of kilometers (e.g. Ginkgo flow of the Frenchman Springs Member of the Columbia River Basalts has a flow length of 500 km).
residual_lava_thickness_submarine::Float64- Residual lava thickness for submarine eruptions in meters
decimation_factor::Int64- Topography grid decimation factor for 1D lava flow model grid
initial_magma_flush_steps::Int64- Number of time steps for initial magma flush
magma_flush_factor::Float64- Factor that determines the amount of magma to flush for flush during magma flush time steps
porosity_initial_lava_flow::Float64- Initial porosity of lava flow in fraction used to decompact extruded gabbroic magma to account for vesicles. This parameter is not used to compact lava flows during burial. Instead, compaction properties associated with the material type are used. This allows for the decompaction of lava flows during eruption to account for porosity from vesicles and the preservation of thickness during burial due to chemical compaction and rigidity of the basalt matrix.
decay_depth_lava_flow::Float64- Depth at which the porosity of lava flow decays to zero in meters. This parameter is used to compact lava flows during burial. Instead, compaction properties associated with the material type are used. This allows for the decompaction of lava flows during eruption to account for porosity from vesicles and the preservation of thickness during burial due to chemical compaction and rigidity of the basalt matrix.
eruption_interval_yr::Float64- Eruption interval in years