CRUST 5.1 a global crustal model at 5 x 5 degrees updates: ------- the version CRUST 5.1 is an updated version of CRUST 5.0. We do not recommend to use the old version since it has substantial bugs in some places (e.g. shelves, Bay of Bengal, Eurasia, U.S., some transitional areas). if you find any further inconsistencies, please let us know (maybe before a meeting is coming up???). We hope this model is of use in a large community and it will grow with every feedback. short description: ----------------- The global crustal model uses a type key to assign crustal structure at a 5 x 5 deg scale. Data were gathered from seismic experiments and averaged globally for similar geological and tectonic settings (such as Archean, early Proterozoic, rifts etc.). These averages were used to assigned structure to regions without seismic information (e.g. most of Africa, South America). Ice and sediment thicknesses where gathered from published maps. Bathymetry and topography is that of ETOPO5. The global model is composed of 139 key 1d-profiles (the crustal types) where one of these profiles is assigned to each 5 x 5 degree cell. Each individual profile is a 7 layer 1D-model with 1) ice, 2) water, 3) soft sediments, 4) hard sediments, 5) upper crust, 6) middle crust and 7) lower crust. Parameters VP, VS and rho are given explicitly for these 7 layers as well as the mantle below the Moho. the files: --------- the model consists of three files: a) CNevelvatio.txt: this is bathymetry and topography b) CNtype.txt: this is the global model c) CNtype_key.txt: this is the file with the profiles a) and b) are given tile by tile from -180 to 180 deg longitude and 90 - -90 deg latitude. The first number is for the tiles with midpoint 87.5N, -177.5E, the second one is 87.5N -172.5E, aso, and the last one is the one with 87.5S, 177.5E. suggested reading routine: ------------------------- readCNt7.f and readCN7vr.f are FORTRAN code which reads the model and give out maps of topography of the boundaries (readCNt7.f) and the seismic velocities and density (readCN7vr.f). The output maps are 72x36 numbers now going from 0 to 360 deg E (first number is at 87.5N, 2.5E). The reading routines should also give out some other maps such as global topography in km, sediment thickness, ice thickness, total crustal thickness (where bathymetry is included). REMEMBER: Water and ice layer are flipped after this routine so that water now is layer 1 and ice layer 2. There will be 8 boundary maps, the first (map.t0) is top of water, while all the others define the bottom of the layers: map.t1: bottom of water map.t2: bottom of ice map.t3: bottom of soft sediments map.t4: bottom of hard sediments map.t5: bottom of upper crust map.t6: bottom of middle crust map.t7: bottom of lower crust=MOHO. These maps are all real topography, i.e. the depth with respect to sea level, not with respect to the actual surface. Therefore, map.t7 and map.thick (actual crustal thickness) are not the same! A routine which returns the model at a given location (interactive input) is getCNpoint.f. On a UNIX machine, don't forget to compile the code: e.g. for getCNpoint f77 getCNpoint.f -o getCNpoint IMPORTANT NOTE ON THICKNESS OF THE WATER LAYER: ----------------------------------------------- the water thicknesses given in c) are only crude estimates and are not to be used in the model! Routine readCNt7.f replaces the water thickness with the true bathymetry (averaged to 5x5 degrees). Routine getCNpoint returns the elevation/bathymetry. The version after Feb23,98 replaces the water thickness in the 7-layer column by this value automatically (earlier versions returned the crude estimates). The crustal thickness is the thickness of the crustl without the water layer. -------------------------------------------------------------------- Further description can be found in: Mooney, Laske and Masters, Crust 5.1: a global crustal model at 5x5 degrees, JGR, 103, 727-747, 1998. A reprint can be requested: mooney@andreas.wr.usgs.gov (glaske@ucsd.edu, gmasters@ucsd.edu) new web site: ------------ the crustal model is on the web: http://mahi.ucsd.edu/Gabi/crust.html http://quake.wr.usgs.gov/study/CrustalStructure/ if you use the anonymous ftp from there, simple save the files onto your machine (don't print them into a file!). new on public demand: -------------------- there is a little fortran routine called map2gmt. This routine asks for the name of one of the map. files. (e.g. map.t1). The output file is a .gmt file (e.g. map.t1.gmt). This file can be used in GMT (xyz2grd) to plot the maps. Gabi Laske