LIST OF FIGURES
Figure 1: Upon starting the GIS database system, the topography for the Middle East and North Africa is displayed by default on the display window next to the main menu
Figure 2: Projection and set map extent menus. Map projections can be set first by clicking on "Set map projection ..." from the main menu (see Figure 1). Then a new projection can be set up by simply clicking on one of the available four projection buttons. The default projection is Mercator. To set a new map area first the "Set map limits ..." button is activated (see Figure 1). Then, a new menu allows the user to change map limits to either one of the three geographic areas (Middle East and North Africa, Middle East, North Africa) or to choose a specific latitude and longitude coordinates by typing the values.
Figure 3: From the data set portion of the main menu (see Figure 1), geographic features can be accessed. This menu opens from "Geographic Data Sets ..." and allows the user to display the available layers of geographic information. In this figure, land and oceans have been shaded and coast lines, country borders and rivers have been displayed. In order to georeference the map, a latitude-longitude grid can be displayed from "Latitude Longitude Grid ...".6
Figure 4: Example metadata file for geographic data. By simply clicking on "metadata ...", a new menu opens. Metadata for each separate different layer or for all geographic data sets can be displayed . In this figure, the metadata from "About all of them ..." is displayed as an example.
Figure 5: The geophysical data sets are accessible through a separate menu: "Geophysical Data Sets ..." (see Figure 1). This menu allows to display seismicity, seismic station locations and crustal scale cross section interpretations. This figure shows how to display the events from the ISC catalog and the resulting map.
Figure 6: Seismic events which have the CMT focal mechanism solutions can be displayed as simple points by just checking "CMT Catalog" box. The focal mechanisms can also be displayed with a menu from "Plot focal mechanisms ...". This menu allows plotting fixed size beach balls, or allows to plot them with variable sizes depending on the magnitude. It also allows to select an area or a particular event for plotting with an offset. This figure shows the entire data set for the Middle East and North Africa with zero offset.
Figure 7: This figure shows how only one event can be selected and its focal mechanism is displayed with an offset from the epicenter. The information icon "i" allows to obtain all available information for any event by clicking on the icon and then on the event. In this example information was requested for the same event whose focal mechanism is displayed.
Figure 8: Seismic station locations are also under the geophysical data set menu. In this figure the short period stations and the broad band stations have been selected for display. They are shown with different symbols which are described in the legend.
Figure 9: Other types of data included under geophysical data sets are the crustal scale cross section locations and their interpretations. All available published interpretation of seismic or gravity data were digitized and they are stored in the database system. Their location can be displayed by checking the "Display profile locations" check box. Cross sections can be displayed by opening the "display crustal x-sections ..." menu and selecting either profile 1 or 2 or 3.
Figure 10: Saudi Arabian refraction profile interpretation and two gravity modeling results are shown in this figure.
Figure 11: The geological data set can easily be displayed with the help of some simple menus. This figure shows how to display the tectonic map of the Middle East and a legend for it.
Figure 12: From the geological data sets, the mine locations for Algeria, Libya, Iran and Iraq can be displayed together with a legend. Information about each mine site can be obtained by selecting the "i" icon and the clicking on a mine location.
Figure 13: Images and grids can be accessed from the "Images/Grids ..." menu which opens from the main menu. The Moho grid has been selected and displayed as an example. A color bar can be easily added to the display as shown in this figure. The "add color scale ..." menu allows the user to specify the minimum value, the desired interval, and the units (km or mgals) for the color bar.
Figure 14: Other data like Bouguer and Free-air gravity values have been girdded directly from points and contours. This figure shows the available Bouguer gravity data coverage.
Figure 15: Map showing the point and contour data used in obtaining the gridded Bouguer gravity map shown in Figure 14.
Figure 16: Metadata are also available for the coverages used to generate the Bouguer gravity grid. These metadata are available through the "metadata for the coverages ..." menu. As an example, the information for the Egypt contours is displayed in this figure.
Figure 17: The "Images/Grids ..." also launches the "Profile maker ...". This menu allows the user to extract a cross section of one or more grids. This figure shows the profile maker menu and how grids are selected. In this example, two arbitrary points have been entered interactively from the screen with the mouse, and topography, Moho, and basement have been selected. The cross section location can be seen on the location map above, and the corresponding cross section below it. Note that the line connecting the profile and points is a great circle path.
Figure 18: A mosaic of five Landsat TM images covering the entire Dead Sea fault system has been displayed over topography represented as a hill shaded image.
Figure 19: A user with ArcPlot knowledge can display his/her own data sets. This menu opens from "Run ArcPlot commands ..." from the main menu (see Figure 1). Any data included in this widow will be redisplayed when zooming in or out until the user clears these commands from this window.
Figure 20: Default line, point, or shade symbols can be changed from "Line/Marker/Shade Sets ..." menu available from the main menu (see Figure 1). This figure shows some scrolling marker (point) , line and shade sets. The point and text size, and the thickness of lines can also be changed.
Figure 21: Hardcopies in different formats can be generated. This figure shows the menu "Hardcopy ...". Once the output format is selected, an output directory and file name need to be entered. An extension to file names will be added.
Figure 22: Any menu session configuration can be saved. The "Save Algorithm ..." menu allows the user to specify output directory and name of the file storing a description of his/her work. This file can later be loaded from the "Load algorithm ..." menu.
Figure 23: Our new Web page is designed to give maximum flexibility to outside researchers in accessing our databases.
Figure 24: ArcInfo Web access is a significant part of our efforts. With this system a user who does not have access to ArcInfo can still reach all of our databases over the Internet.
Figure 25: The seismic events and stations used in this study are located in northwest Morocco. The triangles denote the 1 Hz seismic stations; the 8 phosphate mine explosions are located inside the oval; the squares mark the epicenters of the earthquakes; and "Makris" and "Wigger" are the refraction profiles from which velocity information was obtained.
Figure 26: (a) Velocity seismogram and spectrogram for explosion Xa recorded at station KSI. Notice the two time independent modulations. (b) A different source of similar size, Xb, recorded after traveling about the same path and distance as Xa. Note what may be a second Pg arrival and its interference effects by comparing with the recorded Xa data. (c) Signal from Xa at TNF after crossing the Middle -High Atlas junction. (d) Explosion Xb filtered by the same crustal structure. Propagation effects seem to dominate the signal in comparison with source effects.
Figure 27: (a) The 5-10 Hz Pg/Sg ratio test sorted by source. (b) The more precise 10- 15 Hz Pg/Sg ratio test. See text for information about source Qd, which is most likely an explosion.
Figure 28: Regional tectonic elements of Syria, the location of the refraction profile is shown with the thick line.
Figure 29: Example of refraction modeling. Travel-time plot shows observed arrivals along with modeled travel times of refracted arrivals through velocity model. Travel times reduced at 6 km/s. Numbers on velocity model indicate seismic velocity in km/s. 6 km/s layer represents basement.
Figure 30: The final model. Interfaces in the model not corresponding to velocity changes are shown as short dotted lines. Uncertain interfaces positions shown as long dashed lines.
Figure 31: Location of the three-component broadband stations used in our receiver function study. The models for each station that have reasonably good receiver functions are shown on the top and bottom of the map.
Figure 32: An example of six of the waveform fits from the receiver function inversions. The stacked receiver function from station BGIO was the poorest fit from the data that we inverted.
Figure 33: An example of the RMS error surface for the stacked receiver function from station KEG. The layer error surfaces were obtained by holding the other eight model parameters constant while the layer shear-wave velocity and thickness were allowed to vary.
Figure 34: A comparison of crustal models beneath station BGIO based on linearized-least-squares inversion (top) and our grid search inversion (bottom).