pygmt.Figure.meca

Figure.meca(spec, scale, convention=None, component='full', longitude=None, latitude=None, depth=None, plot_longitude=None, plot_latitude=None, event_name=None, no_clip=False, projection=None, region=None, verbose=False, panel=False, transparency=None, **kwargs)

Plot focal mechanisms.

The following focal mechanism conventions are supported:

Supported focal mechanism conventions.

Convention

Description

Focal parameters

Remark

"aki"

Aki and Richard

strike, dip, rake, magnitude

angles in degrees

"gcmt"

global centroid moment tensor
strike1, dip1, rake1,
strike2, dip2, rake2,
mantissa, exponent
angles in degrees;
seismic moment is
\(mantissa * 10 ^ {exponent}\)
in dyn cm

"mt"

seismic moment tensor
mrr, mtt, mff,
mrt, mrf, mtf,
exponent
moment components
in \(10 ^ {exponent}\) dyn cm

"partial"

partial focal mechanism
strike1, dip1, strike2,
fault_type, magnitude
angles in degrees;
fault_type means +1/-1 for
normal/reverse fault

"principal_axis"

principal axis
t_value, t_azimuth, t_plunge,
n_value, n_azimuth, n_plunge,
p_value, p_azimuth, p_plunge,
exponent
values in \(10 ^ {exponent}\) dyn cm;
azimuths and plunges in degrees

Full GMT docs at https://docs.generic-mapping-tools.org/6.6/supplements/seis/meca.html.

Aliases:

  • A = offset

  • B = frame

  • C = cmap

  • E = extensionfill

  • Fr = labelbox

  • G = compressionfill

  • L = outline

  • T = nodal

  • W = pen

  • p = perspective

  • J = projection

  • N = no_clip

  • R = region

  • S = scale/convention/component

  • V = verbose

  • c = panel

  • t = transparency

Parameters:

  • spec (str, 1-D numpy array, 2-D numpy array, dict, or pandas.DataFrame) –

    Data that contain focal mechanism parameters.

    spec can be specified in either of the following types:

    • str: a file name containing focal mechanism parameters as columns. The meaning of each column is:

      • Columns 1 and 2: event longitude and latitude

      • Column 3: event depth (in kilometers)

      • Columns 4 to 3+n: focal mechanism parameters. The number of columns n depends on the choice of convention (see the table above for the supported conventions).

      • Columns 4+n and 5+n: longitude and latitude at which to place the beachball. 0 0 plots the beachball at the longitude and latitude given in the columns 1 and 2. [optional; requires offset=True].

      • Last Column: text string to appear near the beachball [optional].

    • 1-D np.array: focal mechanism parameters of a single event. The meanings of columns are the same as above.

    • 2-D np.array: focal mechanism parameters of multiple events. The meanings of columns are the same as above.

    • dict or pandas.DataFrame: The dict keys or pandas.DataFrame column names determine the focal mechanism convention. For the different conventions, the combination of keys / column names as given in the table above are required.

      A dict may contain values for a single focal mechanism or lists of values for multiple focal mechanisms.

      Both dict and pandas.DataFrame may optionally contain the keys / column names: latitude, longitude, depth, plot_longitude, plot_latitude, and/or event_name.

    If spec is either a str or a 1-D or 2-D numpy array, the convention parameter is required to interpret the columns. If spec is a dict or a pandas.DataFrame, convention is not needed and ignored if specified.

  • scale (float or str) – scale[+aangle][+ffont][+jjustify][+l][+m][+odx[/dy]][+sreference]. Adjust scaling of the radius of the beachball, which is proportional to the magnitude. By default, scale defines the size for magnitude = 5 (i.e., scalar seismic moment M0 = 4.0E23 dyn cm). If +l is used the radius will be proportional to the seismic moment instead. Use +s and give a reference to change the reference magnitude (or moment), and use +m to plot all beachballs with the same size. A text string can be specified to appear near the beachball (corresponding to column or parameter event_name). Append +aangle to change the angle of the text string; append +ffont to change its font (size,fontname,color); append +jjustify to change the text location relative to the beachball [Default is "TC", i.e., Top Center]; append +o to offset the text string by dx/dy.

  • convention (Optional[Literal['aki', 'gcmt', 'mt', 'partial', 'principal_axis']], default: None) – Specify the focal mechanism convention of the input data. Ignored if spec is a dict or pandas.DataFrame. See the table above for the supported conventions.

  • component (Literal['full', 'dc', 'deviatoric'], default: 'full') –

    The component of the seismic moment tensor to plot. Valid values are:

    • "full": the full seismic moment tensor

    • "dc": the closest double couple defined from the moment tensor (zero trace and zero determinant)

    • "deviatoric": deviatoric part of the moment tensor (zero trace)

  • longitude/latitude/depth – Longitude(s), latitude(s), and depth(s) of the event(s). The length of each must match the number of events. These parameters are only used if spec is a dictionary or a pandas.DataFrame, and they override any existing longitude, latitude, or depth values in spec.

  • plot_longitude/plot_latitude – Longitude(s) and latitude(s) at which to place the beachball(s). The length of each must match the number of events. These parameters are only used if spec is a dictionary or a pandas.DataFrame, and they override any existing plot_longitude or plot_latitude values in spec.

  • event_name (str | Sequence[str] | None, default: None) – Text string(s), such as event name(s), to appear near the beachball(s). The length must match the number of events. This parameter is only used if spec is a dictionary or a pandas.DataFrame, and it overrides any existing event_name labels in spec.

  • labelbox (bool or str) – [fill]. Draw a box behind the label if given via event_name. Use fill to give a fill color [Default is "white"].

  • offset (bool or str) – [+ppen][+ssize]. Offset beachball(s) to the longitude(s) and latitude(s) specified in the last two columns of the input file or array, or by plot_longitude and plot_latitude if provided. A line from the beachball to the initial location is drawn. Use +ssize to plot a small circle at the initial location and to set the diameter of this circle [Default is no circle]. Use +ppen to set the pen attributes for this feature [Default is set via pen]. The fill of the circle is set via compressionfill or cmap, i.e., corresponds to the fill of the compressive quadrants.

  • compressionfill (str) – Set color or pattern for filling compressive quadrants [Default is "black"]. This setting also applies to the fill of the circle defined via offset.

  • extensionfill (str) – Set color or pattern for filling extensive quadrants [Default is "white"].

  • pen (str) – Set (default) pen attributes for all lines related to the beachball [Default is "0.25p,black,solid"]. This setting applies to outline, nodal, and offset, unless overruled by arguments passed to those parameters. Draws the circumference of the beachball.

  • outline (bool or str) – [pen]. Draw circumference and nodal planes of the beachball. Use pen to set the pen attributes for this feature [Default is set via pen].

  • nodal (bool, int, or str) –

    [nplane][/pen]. Plot the nodal planes and outline the bubble which is transparent. If nplane is

    • 0 or True: both nodal planes are plotted [Default].

    • 1: only the first nodal plane is plotted.

    • 2: only the second nodal plane is plotted.

    Use /pen to set the pen attributes for this feature [Default is set via pen]. For double couple mechanisms, nodal renders the beachball transparent by drawing only the nodal planes and the circumference. For non-double couple mechanisms, nodal=0 overlays best double couple transparently.

  • cmap (str) – File name of a CPT file or a series of comma-separated colors (e.g., color1,color2,color3) to build a linear continuous CPT from those colors automatically. The color of the compressive quadrants is determined by the z-value (i.e., event depth or the third column for an input file). This setting also applies to the fill of the circle defined via offset.

  • no_clip (bool, default: False) – Do not skip symbols that fall outside the frame boundaries [Default is False, i.e., plot symbols inside the frame boundaries only].

  • projection (str | None, default: None) – projcode[projparams/]width|scale. Select map projection.

  • region (str or list) – xmin/xmax/ymin/ymax[+r][+uunit]. Specify the region of interest.

  • frame (bool, str, or list) – Set map boundary frame and axes attributes.

  • verbose (bool or str) – Select verbosity level [Full usage].

  • panel (int | tuple[int, int] | bool, default: False) –

    Select a specific subplot panel. Only allowed when used in Figure.subplot mode.

    • True to advance to the next panel in the selected order.

    • index to specify the index of the desired panel.

    • (row, col) to specify the row and column of the desired panel.

    The panel order is determined by the Figure.subplot method. row, col and index all start at 0.

  • perspective (list or str) – [x|y|z]azim[/elev[/zlevel]][+wlon0/lat0[/z0]][+vx0/y0]. Select perspective view and set the azimuth and elevation angle of the viewpoint [Default is [180, 90]]. Full documentation is at https://docs.generic-mapping-tools.org/6.6/gmt.html#perspective-full.

  • transparency (float) – Set transparency level, in [0-100] percent range [Default is 0, i.e., opaque]. Only visible when PDF or raster format output is selected. Only the PNG format selection adds a transparency layer in the image (for further processing).

Examples using pygmt.Figure.meca

Focal mechanisms

Focal mechanisms

Bit and hachure patterns

Bit and hachure patterns

Plotting focal mechanisms

Plotting focal mechanisms