This chapter describes how to install (section 3.1.), operate (section 3.2.), and consult (section 3.3.) the Database of Potential Sources for Earthquakes Larger than 5.5 in Italy (hereinafter referred to as Database), and how to get the most out of its tools and information content.

The first section deals with the basic operations that have to be done to install the Database onto a computer and ensure that it runs correctly. The computer system requirements will also be specified. The second section illustrates all the application menus and commands, their basic features, and the tasks they perform. Full descriptions about how to use them are also given. Finally, the third section presents and comments several examples of actual Database records that will guide the user through the practice of interacting with it and familiarising with all its features.

The Database consists of several data tables and other files organised in an easy-to-understand hierarchical structure. It requires a properly working copy of MapInfo® 4.0 or higher already running on your computer. The Database can be run directly from the CD or copied onto the hard disk. This second option is strongly recommended for full and faster performance but it requires about 450 Mb of free disk space regardless of the platform of your choice. In either case, the Database can be run directly or through a specifically designed web interface. To run it directly simply click on the DISS.mbx icon within the folder database and wait for all the files to load properly. To run it through the web interface just click the Startup icon and follow the instructions. The web interface was designed and operates properly under Microsoft Explorer® 5 or higher version, both on Macintosh and PC. Some of the commands will not work properly under Netscape® regardless of the version used.

The full configuration of the Database consists of three main folders, named database, images and pages, and of the html file startup.html. The folder database contains everything that is needed to run the Database correctly, including empty folders used to store export files temporarily. The user may remove files that are no longer used, but notice that removing empty folders or modifying the overall structure of the Database will prevent it from operating properly.

To install the Database on your Macintosh simply drag and drop the folders database, images and pages and the html file startup.html from the CD into a new empty folder on your hard-disk (the name of this folder is arbitrary; we suggest "DISS 2.0"). The Macintosh version does not require any further modification of the files and the Database is immediately ready to operate.

Operating system: W9x or later running on a Pentium® or higher performance machine.

To install the Database on your PC simply drag and drop, or copy and paste, the folders database, images and pages and the html file startup.html from the CD into a new empty folder on your hard-disk (the name of this folder is arbitrary; we suggest "DISS 2.0"). Since all files on the CD are read-only, the user must modify their properties to allow the system to operate correctly. To do this click Start > Find > Files or Folders..., set name " *.* ", set find in "C:\(folder name)", check Search in the subfolder check-box, and click the Find button. Then select all files listed in the pick-list frame, right-click the selection and then click Properties from the pop-up menu. Unselect the read-only check-box and select the archive check-box. Click the OK button. This operation may take a while since over 4,000 files and folders are being selected and modified at once.

The File Menu contains commands that allow the user to manage the output options of the Database, to exit the MapBasic® application (DISS.mbx, § 2.1.2.) and enter a "normal" MapInfo® session, or to exit the entire procedure (fig. 3.2).

The active graphic window can be saved as an image in BMP or PICT format, respectively for PC and Macintosh platforms. A window will remind the user that the image will be saved as a file named Export.BMP or Export.PICT located in a folder named Quakes.

This command allows the user to close DISS.mbx, the MapBasic® application that manages the Database, and enter a standard MapInfo® session. All the tables that were automatically opened by the Database will remain open, and the user will be allowed to continue working with the standard MapInfo® toolbars and commands. Conversely, all menu items that correspond to typical Database functions (e.g., displaying Felt Reports, displaying Previous Fault Compilations) will disappear. To re-enter the Database, follow the File > Run MapBasic Program… path, specifying that the name of the program is DISS.mbx.

3.2.2.5. File > Exit MapInfo®

Use this command to exit both the Database and MapInfo®. Although a confirmation dialog window was not foreseen, the application will ask if you want to save changes made to any of the existing tables. If you do not intend to save any changes to the Database, click Discard All to eliminate temporary tables that the application may have created dynamically in response to a request for a specific function (e.g. View > Felt Reports, see § 3.2.3.9.).

This drop-down menu contains commands divided into five groups (fig. 3.3) that correspond to the different categories of seismological data and their complementary information embodied in the Database (see section 2.1. for a conceptual introduction to the Database and to the types of data contained in it). The menu allows the user to select items to be loaded into the screen map, following the typical multi-layer structure of GIS applications. As a whole, the first four groups can be regarded as the "cold body" of the Database. They deal with geographic/topographic information, administrative information, catalogues of historical and instrumental seismicity, and other pertinent information. The fifth group can be regarded as the "hot body" of the Database for it deals with information about the Seismogenic Sources and the Tectonic Lineaments.

This command allows the user to zoom and centre the whole Italian territory in the active window. It is used to restore the startup conditions after manipulations involving zooming and panning. The command will not remove, hide, or modify any layer that may have been added to the background.

This command prompts a lower level drop-down menu that allows the user to choose among four different representations of the Italian land-surface, three of which are obtained from a Digital Elevation Model (Carrozzo et al. [1981]; see § 2.2.5.3.1.): (1) Colour Shaded Relief, (2) B/W Shaded Relief, (3) Colour-Coded, (4) coastline only with no topography. Most of the European and Mediterranean countries are also displayed along with colour (for options 1 and 3) or B/W (for option 2) filled contours of the Mediterranean Sea bathymetry. No bathymetry is shown with the Outline Only option.

The user may select the preferred representation by clicking on one of the four items displayed in the drop-down menu:

Follow this path to operate with a coloured shaded-relief topographic base.

Follow this path to operate with a colour-coded topographic base.

Follow this path to operate with a grey-scale shaded relief topographic base.

Follow this path to operate without any topographic base for faster performance (only coastlines and national boundaries are displayed).

The Digital Topography layer includes both raster and vector images. It will stay in the background while you browse the Database unless the order of the layers is changed manually from the Layer Control dialog window. Notice that altering the order of the layers may obscure the content of other layers. All the layers that are added by the user from the other menus or menu items will be arranged on top of the previously loaded layers.

Three different options for the drainage network coverage can be displayed using this command. No additional information is supplied with these layers. All drainage is represented by thin blue lines (rivers) or solid blue regions (lakes).

Follow this path to clear the active drainage coverage.

Follow this path to display the main Italian rivers and the main Italian lakes.

Follow this path to display the main and intermediate Italian rivers and the main Italian lakes.

Follow this path to display the full hydrographic network and the main Italian lakes.

This command prompts the application to display one out of three classes of administrative boundaries. Clicking inside an outlined region with the Object Info tool (§ 3.2.4.8.) returns information on the corresponding administrative unit. The information supplied includes: full name, hierarchy level, "ISTAT code", and area (in km2). All administrative boundaries are shown as thin black lines.

This command allows the user to display Italian cities selected from four classes based on their administrative relevance. Clicking a city symbol with the Object Info tool (§ 3.2.4.8.) returns information on the city’s name, location (latitude, longitude), elevation above sea level, area (of the municipality, in km2) and population.

Use this command to display the catalogue of Italy's instrumental seismicity, which covers a 16 years time span from January 1985 to December 2000 and is taken from the official bulletin of the INGV seismometric network. Each earthquake is shown as a solid white circle. Clicking one of these symbols with the Object Info tool returns the essential parameters of the earthquake (see § 2.2.5.2.1. for further details).

This command allows the user to display one of the catalogues of Italy's historical seismicity available at the end of the year 2000 (see § 2.2.5.2.2.). The three catalogues can be displayed either separately or together, and the earthquakes are shown with squares of different colour according to the catalogue to which they belong (blue for the CFTI, purple for the NT, and red for the CPTI). Clicking one of these symbols with the Object Info tool returns the essential parameters of the earthquake.

Follow this path to display the earthquakes contained in the CFTI 3 Catalogue [Boschi et al., 2000].

Follow this path to display the earthquakes contained in the NT 4.1.1 Catalogue [Camassi and Stucchi, 1997].

Follow this path to display the earthquakes contained in the Catalogo Parametrico dei Terremoti Italiani [CPTI Working Group, 1999].

This command allows the user to select and display the distribution of intensities associated with a specific historical earthquake according to the NT 4.1.1/DOM 4.1 and the CFTI 3 catalogues. All the localities where any given earthquake was felt are pin-pointed with a little red flag labelled with a roman numeral indicating the intensity value that was assigned to it. Clicking the little flag with the Object Info tool (§ 3.2.4.8.) returns the full name and the geographic coordinates of the locality.

Follow this path to show the intensity distribution associated with earthquakes contained in the CFTI 3 catalogue [Boschi et al., 2000]. A window will open allowing the user to select the earthquake of interest from a pick-list. If the active window is not centred on the epicentral region of the chosen earthquake the application automatically moves and resizes it.

Follow this path to show the intensity distribution of earthquakes contained in the NT 4.1.1 catalogue [Camassi and Stucchi, 1997] that occurred prior to 1900 AD. A window will open allowing the earthquake of interest to be selected from a pick-list. If the active window is not centred on the epicentral region of the chosen earthquake the application automatically moves and resizes it.

Follow this path to show the intensity distribution of earthquakes contained in the NT 4.1.1 catalogue [Camassi and Stucchi, 1997] that occurred since 1900 AD. A window will open allowing the earthquake of interest to be selected from a pick-list. If the active window is not centred on the epicentral region of the chosen earthquake the application automatically moves and resizes it.

Follow this path to clear the currently displayed felt report and resume initial conditions in the active window.

This command allows the user to choose among a wide selection of maps representing fault compilations prepared and published by various investigators for different parts of Italy or, in a few cases, for the whole country. A pick-list is shown where the compilations are listed in geographical order, from North to South. The selected compilation is shown in its correct geographical position since all maps are georeferenced with the best accuracy allowed by their characteristics. The compilations are displayed above the topographic base but below all the other layers. This allows the user to overlay other layers of data, including the seismogenic sources, and compare them with the information shown in the compilation itself (see § 2.2.5.2.3. and 3.3.3.2. for further information). The complete list of the available Previous Fault Compilations is presented in Appendix III.

This command is highlighted only when a Previous Fault Compilation is displayed. Follow this path to access information about the compilation (Year of publication, Title, Author(s), Reference(s)).

This command can be used to display additional geophysical and/or seismological data. They include sets of complementary data that have been embedded into the Database to expand its capabilities. These datasets include the direction of minimum horizontal stress axes, a model of seismogenic zonation, the path of regional or local water divides, and others (see § 2.2.5.2.4. for further details). The dataset to be shown can be selected from a pick-list. When a set of additional data is displayed, the application highlights the command Hide Selected Additional Data that can be used to remove it from the active window. The complete list of the available Additional Data is presented in Appendix IV.

This command is highlighted only when a set of additional data is displayed. Follow this path to access information about the Additional Data (Year of publication or compilation, Description, Author(s), Reference(s)).

This command gives access to a lower level drop-down menu that deals with the main and original body of information embedded into the Database. The seismogenic sources are divided into six main categories (From Geologic/Geophysical Data; Historical-Well Constrained with Geological Background; Historical-Well Constrained, no Geological Background; Historical-Poorly Constrained with Geological Background; Historical-Poorly Constrained, no Geological Background; Deep), and can be displayed separately or simultaneously (see § 2.2.3. for further details and a description of each individual source type). To retrieve all the information available in the Database concerning each source the user must first select the source by clicking into its map symbol, then select an item from the Source Info drop-down menu (see § 3.2.5.). The essential source parameters may also be viewed through the Object Info tool (§ 3.2.4.8.).

Follow this path to display in a dynamic layer of the cartographic interface the seismogenic sources belonging to the Geologic/Geophysical category (see § 2.1.3., 2.2.3.1., and 3.3.2.1. for a comprehensive description of this source type). Each seismogenic source will be displayed as a yellow rectangle and a yellow line parallel to one side of it. The first represents the surface projection of the fault plane with its size and orientation; the second represents its cut-off. Coseismic fault scarps are represented as red barbed lines (with barbs on the down-thrown block).

Sources of this category are divided into two sub-sets that can be displayed separately or at the same time (see § 2.1.3., 2.2.3.2., 2.2.3.3., 3.3.2.2. and 3.3.2.3. for a comprehensive description of this source type). Since sources of this type derive exclusively from good quality intensity data using the method of Gasperini et al. [1999], their orientation is calculated but their plunge and dip are unknown. They are represented as oriented and scaled rectangular boxes.

Follow this path to display in a dynamic layer of the cartographic interface the seismogenic sources belonging to the Historical-Well Constrained with Geological Background category. Sources of this category are shown in blue to highlight them with respect to the remaining intensity-based sources.

Follow this path to display in a dynamic layer of the cartographic interface the seismogenic sources belonging to the Historical-Well Constrained, no Geological Background category. Sources of this category are shown in black.

Follow this path to display simultaneously the two previous source types.

Sources of this category are divided into two sub-sets that can be displayed separately or at the same time (see § 2.1.3., 2.2.3.4., 2.2.3.5., 3.3.2.2., and 3.3.2.3. for a comprehensive description of this source type). Sources of this type derive exclusively from intensity data using the method of Gasperini et al. [1999], but in this case the quality of the solution was not good enough to allow their representation as oriented rectangular boxes. For this reason they are shown as scaled circles.

Follow this path to display in a dynamic layer of the cartographic interface the seismogenic sources belonging to the Historical-Poorly Constrained with Geological Background category. Sources of this category are shown in blue to highlight them with respect to the remaining intensity-based sources.

Follow this path to display in a dynamic layer of the cartographic interface the seismogenic sources belonging to the Historical-Poorly Constrained, no Geological Background category. Sources of this category are shown in black.

Follow this path to display simultaneously the two previous source types.

Follow this path to display in a dynamic layer of the cartographic interface the seismogenic sources belonging to the Deep category (see § 2.1.3., 2.2.3.6., and 3.3.2.4. for a comprehensive description of this source type). Sources of this category are shown as open purple scaled hexagons.

Since there may exist multiple solutions for the same physical seismogenic sources (see § 2.2.3.7. for a discussion on this subject), use this command to display all and only the set of sources that is "preferred" by the compilers of the Database.

This command gives access to a lower level drop-down menu that allows the user to display the Tectonic Lineaments. These are linear tectonic features taken from published literature (see § 2.2.3.10.); they are shown as yellow dashed lines. To retrieve information about a lineament the user must first select it by clicking on its map symbol, then select an item from the Lineament Info drop-down menu (see § 3.2.6.).

Follow this path to show only the linear tectonic features that lie perpendicular to the general trend of the main seismogenic sources.

Follow this path to show all the other lineaments.

Follow this path to display simultaneously the two previous types of lineaments.

The Tools menu allows the user to access to the main tools and commands available for a typical working session with the Database (fig. 3.4). The same tools plus other specific MapInfo® tools are also displayed in the MapInfo® Standard Button Pads that are made available upon startup. For a detailed description of the tools of the Standard Button Pad see the MapInfo® User Guide.

This command allows a specific selection to be saved as a MapInfo® table file; when used a pop-up window appears showing the folder and the name of the saved file.

This command provides a closer view of a map. When used the cursor takes the shape of a lens with a plus sign within it. The user can either click the zoom-in cursor in an area to magnify it by a factor of two (this point will became the centre of the zoomed-in view), or drag the cursor over a rectangular area. This area will be enlarged to fit the active window. This command corresponds to the Zoom-in button of the Standard Button Pad.

This command provides a more distant view of a map. When used the cursor takes the shape of a lens with a minus sign within it. The user can either click the zoom-out cursor in an area to reduce it by a factor of two (this point will became the centre of the zoomed-out view), or drag the cursor over a rectangular area. The active window will be reduced to fit this area. This command corresponds to the Zoom-out button of the Standard Button Pad.

This command allows the user to set a specific scale for the active window manually. A Change View dialog window will open where the values of the window width (or the map scale) and the coordinates of the centre of the window can be typed in. This command corresponds to the Change View button of the Standard Button Pad.

This command allows the user to get back to the latest view of the currently active map window prior to any change in map scale or position of the map centre.

This command allows the user to reposition a map within its window. When used the cursor takes the shape of a hand. To move a map click on it, hold down the mouse button and drag the cursor in the desired direction; releasing the mouse button will cause the map to be redrawn at the new location. This command corresponds to the Grabber button of the Standard Button Pad.

This command allows the user to determine the distance between two points or the cumulative distance along a multi-segment path. When used the cursor takes the shape of a cross and a Ruler Window opens. The Ruler Window displays the distance that the ruler is currently measuring and the total of all the distances measured at each segment increment. Double-click to stop measuring. This command corresponds to the Ruler button of the Standard Button Pad.

This command allows the user to view the attributes associated with map objects. When used the cursor takes the shape of a cross. Click on any selectable object to open a window showing the list of attributes. This command corresponds to the Info Tool button of the Standard Button Pad.

This command allows the user to display a graphical scale at the lower left corner of the active window; the graduation changes according to the current level of magnification of the map.

Use this command to locate a seismogenic source belonging to either of the six source types by its full conventional name (SourceName). A dialog window will prompt the user to enter the conventional name of the source to be looked for. Click the OK button to start searching or the Cancel button to quit.

Use this command to locate a seismogenic source belonging to either of the six source types by its numerical identifier (IDSource). A dialog window will prompt the user to enter the identifier of the source to be looked for. Click the OK button to start searching or the Cancel button to quit.

Use this command to choose between two different coordinate systems. Selecting a different coordinate system will affect the indication of the "cursor location" (shown at the left-hand side of the Status Bar at the bottom of the active window) and all the coordinates of any of the objects displayed by the application.

Follow this path to choose the geographic coordinates of the ED50 (European Datum 1950) system.

Follow this path to choose the kilometric coordinates of the UTM Zone 32.

This command allows the user to show or hide the MapInfo® Standard Button Pads. The use of the Standard Button Pads is recommended to experienced users that want to access additional native MapInfo® functions directly from within the Database.

Use this drop-down menu to access the main body of information of the Database (fig. 3.5). To get information on a specific seismogenic source select it with the Select cursor and browse the Source Info menu; note that if no one of the seismogenic source is selected, none of the commands is highlighted (see § 2.2.3. for a detailed description of the source types and of the associated tables containing geometric and kinematic parameters and earthquake recurrence properties).

Through this command the user can display a window that supplies the main geometric and kinematic parameters of the source and informs about the evidence that was used by the compiler to constrain them. The title bar of the window contains the full source name (SourceName) and identifier (IDSource) (fig. 3.6).

Each of the buttons located to the right of the various fields of this window and marked by >> retrieves from the table Assign_References.tab the specific reference from which the information displayed was obtained (the software link that underlies this functionality is described in § 2.2.4.4. and 4.1.4.). Notice that this piece of information is optional: the default is "Compilers of this Database". New links become operational during the Maintenance operations (see section 4.5.).

Each of the buttons located to the right of the various fields of this window and marked by >> retrieves from the table Assign_References.tab the specific reference from which the information displayed was obtained (the software link that underlies this functionality is described in § 2.2.4.4. and 4.1.4.). Notice that this piece of information is optional: the default is "Compilers of this Database". New links become operational during the Maintenance operations (see section 4.5.).

Through this command the user can display a window that contains a full list of summaries of the papers dealing with the identification and characterisation of the selected source, with reference both to geologic evidence and to the associated seismicity (see § 2.2.5.1.). This section gives the reader the opportunity to evaluate the level at which the source has been studied by specialists and provides an overview of the main approaches that have been used to identify and characterise the source itself (fig. 3.8).

fig. 3.8 - View of the dialog box "Summaries of the main studies on the source"

Through this command the user can display a window that presents descriptions and comments concerning what the compiler has or has not found in the literature, the main debated points and the questions that remain open (see § 2.2.5.1.). Unlike the previous case, where previous work is simply presented and summarised objectively, this section is entirely based on personal judgement and as such it forms the "core" of the analysis and the starting point for further investigations (fig. 3.9).

This command opens a dialog window that allows the user to browse through a full list of references concerning the source. The total number of references available for the selected source appears on the title bar of the dialog box. The dialog window consists of two frames: the upper frame contains the name and identifier of the selected source and the identifier of the reference, while the lower frame shows the full reference. For each reference the following information is provided: author(s), year of publication, title, journal/book. The list can be browsed using the arrow buttons at the bottom of the window. Notice that the reference identifier (Code_referenceID, shown as Ref Code in the dialog box) allows any user to locate the paper in the INGV hard-copy archive. The full list of references available for the selected seismogenic source can also be saved as an ASCII file with the Save All button (a pop-up window will appear showing the full path-name of the file where the references are saved) (fig. 3.11).

Use this drop-down menu to access the information regarding the Tectonic Lineaments (see § 2.2.3.10. for a detailed description of the Tectonic Lineaments and of the associated tables) (fig. 3.12). To get information on a specific lineament select it with the cursor and browse the Lineament Info menu; note that if none of the lineaments is selected, none of the menu items is highlighted.

Through this command the user can open a window that supplies the name and reliability of the selected tectonic lineament.

The field Evidence reports the basic geologic evidence taken from the literature that support the existence, the location and the geologic time of activity of the tectonic lineament.

The field Notes lists a series of comments based on personal judgement by the compilers of the Database.

This command opens a dialog window that allows the user to browse through a full list of references concerning the lineament. The total number of references available for the selected lineament appears on the title bar of the dialog window. The dialog window consists of two frames: the upper frame contains the name and identifier of the selected source and the identifier of the reference, while the lower frame shows the full reference. For each reference the following information is provided: author(s), year publication, title, journal/book. The list can be browsed using the arrow buttons at the bottom of the window. Notice that the reference identifier (Code_referenceID, shown as Ref Code in the dialog box) allows any user to locate the paper in the INGV hard-copy archive. The full list of references available for the selected lineament can also be saved as an ASCII file with the Save All button (a pop-up window will appear showing the full path-name of the file where the references are saved).

This drop-down menu allows the user to create simple scenarios of the expected consequences of either a real or a hypothetical normal-depth (upper crustal) earthquake of given magnitude and epicentral location (fig. 3.13). The user can construct different maps showing cities and historical seismicity falling close to epicentral area, as well as the intensities expected at the nearest towns. Maps generated with the Scenarios tool can be saved as MapInfo® tables or printed to create ready-to-use reports. The shaking scenarios are calculated starting from two built-in empirical attenuation relationships (denominated best-case and worst-case) derived from more than 31.000 felt reports listed in the CFTI historical catalogue, version 2 [Boschi et al., 1997]. All scenarios created with commands from this menu can be complemented by any of the information contained in the Database (e.g., seismogenic sources to emphasise the spatial relationships between them and an earthquake that just occurred; administrative boundaries, to highlight the administrative bodies that will be affected by a specific event; etc.).

This command generates a map with a width of 40 km, scaled to fit the window, and centred on the earthquake epicentre. The epicentre is represented as a solid red diamond and is surrounded by three circles with radius of 2.5, 5, and 10 km respectively. The map displays also a graphic scale and a selection of drainage and administrative data. This map size is suitable for exploring details of the topography and settlement distribution of the epicentral region.

This command generates a map with a width of 150 km, scaled to fit the window, and centred on the earthquake epicentre. The epicentre is represented as a solid red diamond and is surrounded by three circles with radius of 5, 10, and 20 km respectively. The map displays also a graphic scale and a selection of drainage and administrative data. This map size is appropriate for a regional-scale appreciation of the effects of earthquakes of any size.

This command generates a map showing the worst-case scenario for the expected consequences of an earthquake of assigned epicentral location and magnitude. The map has a window width of 100 km and shows all the Small towns that would experience intensity III (Mercalli-Cancani-Sieberg scale) and above, labelled with roman numerals (fig. 3.14). The application then presents dialog boxes for printing and/or saving the map.

This command generates a map showing the best-case scenario for the expected consequences of an earthquake of assigned epicentral location and magnitude. The map has a window width of 100 km and shows all the Small towns that would experience intensity III (Mercalli-Cancani-Sieberg scale) and above, labelled with roman numerals. The application then presents dialog boxes for printing and/or saving the map.

This command creates a list of all small towns (Comuni) falling within 25 km of the epicentre. For each town the list includes the full name, the province, latitude and longitude, population, distance from the epicentre, and the intensity expected for the best-case and worst-case scenarios. The application then presents dialog boxes for printing and/or saving the map.

This command extracts all the historical earthquakes falling within 50 km of the epicentral location of a given earthquake from all those listed in the CPTI catalogue. The list can be printed or saved at the user’s convenience. It contains the main geographical and seismological parameters of the earthquakes, such as origin time, nearest locality, epicentral coordinates, maximum intensity, magnitude, number of available intensity reports, source radius, ID, and acronym of the historical catalogue where the earthquake is listed.

This command performs the same task as that of the previous command (see § 3.2.7.6.), but in this case the earthquakes are taken from the CFTI 3 catalogue.

This command performs the same task as that of the previous two commands (see § 3.2.7.6.), but in this case the earthquakes are taken from the NT 4.1.1 catalogue.

This command extracts all the instrumental earthquakes falling within 50 km of the epicentral location of a given earthquake from all those contained in the INGV instrumental bulletin. The resulting earthquake list contains the main seismological parameters. Similarly to all previous cases, the list can be printed or saved at the user’s convenience.

This command clears any previously created scenarios and returns to the standard interface of the Database.

Any user can update the Database by entering new seismogenic sources, modifying the existing ones or adding new background information (see Chapter 4 for details on how to enter new information in the structural and support tables). To update the graphic information after having modified or updated a table and to display correctly the newly-entered information the user has to run an appropriate command chosen from those listed in the Maintenance menu (fig. 3.15).

Use this command after having modified any of the tables that contain historical seismicity (CFTI_q.tab, CPTI_q.tab, and NT_q.tab).

Use this command after having modified the catalogue of instrumental earthquakes (inst_q.tab).

Use this command after having modified any of the tables containing seismogenic sources (SourceGeol.tab, SourceHistA.tab, SourceHistARev.tab, SourceHistB.tab, SourceHistBRev.tab, SourceDeep.tab). This command generates a new SourcePreferred.tab automatically.

Use this command to generate geographical grid tables (e.g.: Grid_010.tab, Grid_025.tab, Grid_050.tab, Grid_100.tab, etc.).

Use this command after having modified the table Tectonic_Lineaments.tab that contains all Tectonic Lineaments. This command updates the tables GenericTectLineaments.tab and TransverseTectLineaments.tab automatically.

Building on previous chapters and sections, this section provides the reader with an effective way to get acquainted with the compound content of the Database and its structure. This task is pursued by guiding the reader through the lines of travel which will better instruct the potential user on how to consult the records of seismogenic sources and the background information that lies behind them.

The following § 3.3.2. gives an overview of several sample records pertaining to the six different categories in which the seismogenic sources are grouped, while § 3.3.3. illustrates a series of examples of the several ways in which an individual seismogenic source record can be analysed within its geologic and seismotectonic context.

To get the most out of this guided tour the user should have already installed the necessary software and correctly copied onto his/her computer all folders and files that form the Database. It is also necessary that the user be already familiar with menu-bars and tools of the Database cartographic interface and with its commands and procedures. The user is also suggested to follow this section with the Database running on the computer and to try to bring forward the content of the Database that is currently illustrated and commented. Refer to Chapter 2 for details concerning the structure of the Database, and to sections 3.1., 3.2. to check the operational procedures.

This section illustrates the content of several records that are considered good representatives of the six categories of seismogenic sources contained in the Database. The six categories (see details about the definition of various categories in § 2.2.3.) are illustrated and commented in four subsections concerning respectively:

a. sources that were derived from geological and/or geophysical investigations (§ 3.3.2.1.);

b. sources that were derived from well constrained and from poorly constrained historical data and for which background geological information is given (§ 3.3.2.2.);

c. sources that were derived from well constrained and from poorly constrained historical data without any background geological information (§ 3.3.2.3.);

d. sources that were derived from historical data which are suspected to be deeper than usual (§ 3.3.2.4.).

For each example in the following sections only the information that can be drawn from the series of items listed in the Source Info down-drop menu will be illustrated. The user is reminded that each seismogenic source included in the Database has been identified and described by the compiler on the basis of the available scientific material, either published or unpublished, and of his/her own judgement. Emphasis will be placed on discriminating which parts of the source record reflect the compiler's expert judgement and which reflect scientific results achieved through investigations carried out independently by other scientists. References pertaining to the illustrated source records are to be found in the reference lists stored in the disk Database.

Seismological information about the Messina Straits source may be obtained from the Seismic Behaviour window, which begins by informing that the most recent earthquake produced by this source is the 28 December 1908 event (fig. 3.17). The expected magnitude for the source is Mw 7.0, which corresponds to the estimated magnitude of the 1908 event. Not coincidentally, this earthquake size is also the size needed to rupture the entire area encompassed by this source in a single event. The expected magnitude for other sources may come from different observations depending on whether the source is correlated with a historical or instrumentally recorded earthquake or is not correlated with any earthquake. The reported magnitude can be either an Me, if derived from intensity data, or an Mw, if measured or derived from empirical relationships between fault size and moment-magnitude.

The Seismic Behaviour window informs that the Irpinia North source is correlated with the 23 July 1930 earthquake (fig. 3.22). Only 70 years have passed since the earthquake occurred, and this alone suggests that a strong earthquake is not likely to be generated by the same source in the near future. However, a strong earthquake occurred in 1980 in southern Irpinia (see Irpinia South source, ID 7) on a different, although quite near, seismogenic source. The expected magnitude for the Irpinia North source is Ma 6.7, which is the estimated magnitude taken from the CPTI Working Group [1999] catalogue. Notice that Ma is an average magnitude obtained by combining with appropriate weights a purely macroseismic magnitude (that is, based on epicentral intensity only), an instrumental magnitude and a magnitude obtained from intensity data using the approach proposed by Gasperini et al. [1999].

The Seismic Behaviour window informs that the Calabria (1783, Mar 28) source is correlated with the 28 March 1783 earthquake (fig. 3.26). Although 217 years have elapsed since 1783, this source is not to likely to generate a new large earthquake soon if one considers that the average recurrence interval of large Italian earthquake sources is generally longer than a millennium. However, the correct characterisation of a source like this is fundamental for understanding the modes of seismic release in the region and assessing the current seismogenic potential. The expected magnitude for the Calabria (1783, Mar 28) source is Ma 6.9, which corresponds to the estimated magnitude taken from the CPTI Working Group [1999] catalogue. Notice that Ma is an average magnitude obtained by combining with appropriate weights a purely macroseismic magnitude (that is, based on epicentral intensity only), an instrumental magnitude and a magnitude obtained from intensity data using the approach proposed by Gasperini et al. [1999].

The expected magnitude for the Cagliese (1781, Jun 03) source is Ma 6.2, which corresponds to the estimated magnitude taken from the CPTI Working Group [1999] catalogue. Notice that Ma is an average magnitude obtained by combining with appropriate weights a purely macroseismic magnitude (that is, based on epicentral intensity only), an instrumental magnitude and a magnitude obtained from intensity data using the approach proposed by Gasperini et al. [1999]. Since the area over which a deep earthquake is felt is generally larger than that of a shallow earthquake, the magnitude estimation for this type of earthquake-derived sources should be considered less accurate than that obtained for other events.

This section describes some of the several ways of exploring how the Database records interact with each other and how a seismogenic source can be investigated in the light of the other data stored in the Database. A few examples will be illustrated below to suggest the user how to use all the possibilities offered by the relational structure of the Database and by its tools. It is recommended that the seismogenic source records be displayed through the Integrated Source Dataset (§ 3.2.3.14.), which represent the compilers’ preferred set of sources (§ 2.2.3.7.), although the user may prefer to view one or more of the layers available under the Seismogenic Source menu (§ 3.2.3.14.). All complementary data can be retrieved by displaying a layer from the menu View (§ 3.2.3.) and/or the menu Scenario (§ 3.2.7.).

An example that may focus attention onto such practice is represented by the Boiano Basin (ID 4), Tammaro Basin (ID 5), and Ufita Valley (ID 6) seismogenic sources, located in the southern Apennines (fig. 3.30). These three sources align along the NW-SE direction, dip toward the northeast and are rather regularly spaced. All three sources have about the same size, suggesting that an earthquake of similar size could be associated with each one of them. In addition, all three sources are characterised by a normal faulting mechanism. All in all, these characteristics suggest that the three sources belong to the same regularly segmented fault system. It is also worth noticing that all three sources have produced a large earthquake in historical times, respectively (North to South) on 26 July 1805 (Ma 6.6), on 6 May 1688 (Ma 6.7), and on 29 November 1732 (Ma 6.6).

The previous section described the possible interrelations among adjacent seismogenic sources. When a seismogenic source is established, either on the basis of geological and geophysical data or using earthquake intensity data, all the available information about its characterisation is included and commented in its exclusive record in the Database. Significant inferences can then be made simply by comparing the spatial properties of adjacent sources. However, new insight about any seismogenic source may come from observations made at a larger scale than that at which an individual source is represented. These observations might not necessarily be mentioned in the source record. This section will briefly elucidate this concept through a few examples.

A stimulating and informative way of acquiring the maximum possible knowledge from the Database is to have a specific seismogenic source plotted against a map or georeferenced table that was prepared outside the framework and objectives of the Database itself. The map or the data are normally taken from the literature in the form of a Previous Fault Compilation (§ 2.2.5.2.3. and 3.2.3.10.), but may also have been added by the compilers as a layer of Additional Geophysical/Seismological Data (§ 2.2.5.2.4.). To get a more complete picture, one or more of the other available layers under the menu View may be added to the overlay at the user's convenience, the only limitation being the readability of the final map. This exercise may suggest answers to several compelling questions, from the most obvious to the most stimulating ones, such as: had the seismogenic source under inspection ever been identified/mapped by other investigators? If so, does the faults/source look about the same? If not, why? Do other faults/sources exist in the region surrounding the seismogenic source at hand, which are not included in the Database? What are the spatial relationships between a specific source and the local topography/drainage/water divide? How far/close does a specific recent earthquake fall from the closest seismogenic source? Clearly, given the number of informative layers supplied with the Database and given the possibility of plotting along new data as they become available (e.g., a new earthquake sequence), the number of possible questions is clearly limited only by the user’s imagination.

A map produced following this reasoning is shown in figure 3.31. The Fucino Basin seismogenic source, ID 2, along with its own Associated Faults, is plotted against a cropped section of the Neotectonic Map of Italy at the scale 1:1,500,000 [Ambrosetti et al., 1987] (the grey scale geocoded bitmap in the background), representing a large portion of the central Apennines. At least three main differences can be readily noticed:

fig. 3.31 - Fucino Basin source, ID 2, plotted over the Neotectonic Map of Italy [Ambrosetti et al., 1987]

Figure 3.33 displays the Best-case Scenario... (§ 3.2.7.4.) for an earthquake whose location (Latitude North 43.81°; Longitude East 12.90°) and magnitude (Mw 6.1) are compatible with the full activation of the Fano Ardizio seismogenic source. The epicentre is located at mid-length directly above the lower fault-edge. The magnitude equals the expected value reported in the Seismic Behaviour window for this source. The map shows that in case of such an earthquake cities within 10 km of the epicentre would suffer a level of damage up to intensity VIII-IX. Intensity VI would be recorded at distances of 25 km to 35 km. This scenario looks somewhat worse than the actual distribution of intensities observed following the 1930 earthquake in Senigallia. This is mainly due to the higher magnitude used for the scenario (Mw 6.1) compared to the magnitude observed in 1930 (Ma 5.9). It is also worth noticing that the intensity distribution shown in the scenario is generally much more regular than that of the actual earthquake. This is a result of the simplified attenuation law used for generating the scenarios, which assumes circular decay of intensity and does not take into account possible local amplification/attenuation effects resulting from the local geology, from earthquake directivity, or from the geometry and kinematics of the source.

Every seismogenic source in the Database is associated with an earthquake that already occurred or is likely to occur. Conversely, not all known earthquakes of magnitude larger than 5.5 have been assigned to an identified and fully characterised seismogenic source. A comprehensive analysis of any earthquake-prone area would require not only the identification of all potential sources of large earthquakes, but also an evaluation of the main characteristics of the minor seismicity.

The Database offers an opportunity to explore in a very easy and effective way the relationships between the largest earthquake associated with a given seismogenic source and the other major/minor earthquakes in its surroundings. This task can be accomplished by generating an overlay of a catalogue of historical earthquakes (§ 3.2.3.8.) and of one of the layers containing seismogenic source (§ 3.2.3.14.).

Figure 3.34 shows an overlay created by displaying the historical earthquakes contained in the Catalogo Parametrico dei Terremoti Italiani [CPTI Working Group, 1999] and the seismogenic sources of the category From Geologic/Geophysical Data. The figure focuses on the central Apennines. The Norcia Basin source, ID 16, is associated with the 14 January 1703 earthquake, but over 50 generally smaller historical earthquakes may be counted within a distance of 20 km from the source centre. This suggests that the region where the Norcia Basin source is located has a quite complex seismic history. However, it is possible to notice that the majority of these smaller earthquakes locate near the southwestern edge of the source, while only few earthquakes appear on the northeastern side, and that the largest events align along a NW-SE direction. The exercise might suggest (1) that sources that have been assigned a certain size might in fact be smaller, (2) that some of the minor seismicity might occur next to the slip patches associated with the largest earthquakes, and (3) that some of the seismogenic sources presented in the Database occur in areas that are characterised by a more complex structure than presently hypothesised.

fig. 3.34 - Norcia Basin source, ID 16, and the historical earthquakes that occurred in its surroundings according to the CPTI catalogue [CPTI Working Group, 1999]