MLOC Plotting Topography

This section deals with plotting topography and/or bathymetry in the map-like plots produced by mloc. Map-like plots include the base plot and its derivatives (selected event plots, ellipse plots, seismicity plots), the direct calibration raypath plot, and the empirical path anomaly plot.

As of v10.5.0 of mloc the only global digital elevation model (DEM) available for plotting topography/bathymetry is ETOPO1. Access to this DEM is different under GMT6 than it is under GMT5, as discussed in the Data Files section.

Calling

Plotting of topography is optional; the default is off. To plot topography in all suitable plots the command dem1 is used.

Color Palette

The default color palette (and the only one supplied in the standard mloc distribution) is topo.cpt. The command cptf can be used to change the color palette if alternative color palettes have been added to /tables/gmt/cpt/. Any of the standard color palettes supplied with a GMT installation can be used for plotting topography in mloc.

High Resolution Topography

The resolution of the global DEM models is adequate for most clusters but in some cases it is desirable to be able to plot topography at higher resolution for the plots that cover a limited area (i.e., the base plot and derivatives). This can be done using the dem2 command, but it requires the user to provide the necessary grid file. A convenient source for such data files is GMTSAR, from which SRTM topography (at 90 m resolution) and ASTER G-DEM topography (at 30 m) can be downloaded in GMT format. The requested region cannot exceed four degrees in latitude or longitude. To keep file size as small as possible, select a region slightly larger than the limits of the base plot.

mloc will make a temporary color palette for the high-resolution plots, based on the default color palette or one selected with the command cptf.

High-resolution grid files can be stored in the cluster directory but since they are rather large (a few tens of MB) and the same file would need to be stored for each series of runs, I recommend storing them in /tables/gmt/dem.