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2 | 2 | Subducting plate |
3 | 3 | ========== |
4 | 4 |
|
5 | | -The subducting plate feature provides the user with the ability to add a subducting slab to the GWB world. To define a slab, the user must specify the `coordinates` where the slab intersects with the surface of the world, which for a subducting plate represents the location of the trench. In the Cartesian coordinate system, `coordinates` are represented by `[x, y]` points (in meters), and in the spherical coordinate system `coordinates` are represented by `[longitude, latitude]` points (in degrees). Additionally, because the trench is simply a line on the surface, the user must also specify the direction that the subducting plate dips from the trench via the `dip point`. The dip point is also represented as a surface point ([x, y] in cartesian, [longitude, latitude] in spherical). |
| 5 | +The subducting plate feature provides the user with the ability to add a subducting slab to the GWB world. To define a slab, the user must specify the `coordinates` where the slab intersects with the surface of the world, which for a subducting plate represents the location of the trench. In the Cartesian coordinate system, `coordinates` are represented by `[x, y]` points (in meters), and in the spherical coordinate system `coordinates` are represented by `[longitude, latitude]` points (in degrees). Additionally, because the trench is simply a line on the surface, the user must also specify the direction that the subducting plate dips from the trench via the `dip point`. The dip point is also represented as a surface point (`[x, y]` in Cartesian, `[longitude, latitude]` in spherical). |
6 | 6 |
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7 | 7 | ```{figure} ./map_view.png |
8 | 8 | :name: view_of_coordinates |
9 | | -:alt: Plume geometry. |
| 9 | +:alt: view of coordinates. |
10 | 10 | :align: center |
11 | 11 |
|
12 | | -Map-view of a world where a trench is defined with three `coordinates`, and contains a slab dipping to the left towards the user-specified `dip point`. |
| 12 | +Map-view of a world where a trench is defined with three `coordinates` (black points), and contains a slab dipping to the left towards the user-specified `dip point` (white point). The slab is coloured by the depth. |
13 | 13 | ``` |
14 | 14 |
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15 | 15 | To create a slab that does not change along-strike, the user can simply specify a number of `segments`. Segments are defined through a `length`, a `thickness`, and an `angle`. When the `angle` and the `thickness` are input as single values and not as arrays, the resulting segment is defined by a straight line segment, and dips away from the trench towards the `dip point` at the specified `angle`, with a uniform `thickness`. However, the segment can vary in `thickness` if the user specifies `thickness` as an array of two values, in which case the segment will still be represented as a staight line segment, but will linearly vary from the first thickness to the second thickness across the `length` of the segment. If the user also inputs `angle` as an array of two values, the segment will be represented as a piece of a circle, where the dip of the segment varies linearly from the first angle to the second angle across the `length` of the segment. Any given segment can vary in `thickness` and in `angle`, and when multiple segments are defined the termination point of a given segment acts as the starting point of the following segment. Combining segments in this way enables a user to define extremely complicated slab geometries down-dip of the trench `coordinates`. |
16 | 16 |
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17 | 17 | ```{figure} ./2D_cross_section.png |
18 | 18 | :name: view_of_segments |
19 | | -:alt: Plume geometry. |
| 19 | +:alt: view of segments. |
20 | 20 | :align: center |
21 | 21 |
|
22 | | -Cross section of a subducting plate feature showing how `segments` can create complicated slab geometries down-dip of the trench. |
| 22 | +Cross section of a subducting plate feature showing how `segments` can create complicated slab geometries down-dip of the trench. Black region represents where the slab is located. |
23 | 23 | ``` |
24 | 24 |
|
25 | | -Additional complexity can be introduced by specifying `sections`, which allow the user to vary the shape of the slab along-strike of the trench. If the trench is defined by $N$ surface `coordinates`, then $N$ `sections` can be specified, where each `section` is mapped to the corresponding `coordinates` of the trench. The `sections` are made up of $M$ `segments` ($M$ does not need to be equal to $N$), thereby creating $N$ unique curves along-strike of the trench, and these `sections` are interpolated along strike using a Bezier interpolation to form a complex 3-dimensional slab that varies along-strike and down-dip. |
| 25 | +Additional complexity can be introduced by specifying `sections`, which allow the user to vary the shape of the slab along-strike of the trench. If the trench is defined by $N$ surface `coordinates`, then _N_ `sections` can be specified, where each `section` is mapped to the corresponding `coordinates` of the trench. The `sections` are made up of _M_ `segments` (_M_ does not need to be equal to _N_, but each section MUST be composed of _M_ segments), thereby creating $N$ unique curves along-strike of the trench, and these `sections` are interpolated along strike using a Bezier interpolation to form a complex 3-dimensional slab that varies along-strike and down-dip. |
26 | 26 |
|
27 | 27 | ```{figure} ./downdip_sections.png |
28 | 28 | :name: view_of_sections |
29 | | -:alt: Plume geometry. |
| 29 | +:alt: view of sections. |
30 | 30 | :align: center |
31 | 31 |
|
32 | | -View of the subducting plate feature showing how `sections` can be used to add along-strike complexity to the slab. Each of the `sections` are made up of unique `segments`, which are then interpolated along-strike using a Bezier interpolation. |
| 32 | +View of the subducting plate feature showing how `sections` can be used to add along-strike complexity to the slab. Each of the `sections` are made up of unique `segments`, which are then interpolated along-strike using a Bezier interpolation. The slab is coloured by the depth. |
33 | 33 | ``` |
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