Low Level Services

Low Level Services are distinguished from High Level Services by the fact that they perform relatively simple data transformations. On the contrary, High Level Services perform specific analyses and methods, utilizing data in order ti produce more sophisticated results, not just simple data elaboration. The Low Level Services, shown it the list, are described in this section:

• Mseed2Ascii
• MiniSEED to ASCII translation
• Seed response calculation
• Seismogram picking tool
• Catalog Filter
• Coordinates Transformation
• Magnitude Conversion
• FilterOverMmin
• FilterWithinTime

Description of Low-Level Services:

• Mseed2Ascii

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• MiniSEED to ASCII translation

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• Seed response calculation

This service uses .seed files (entered from change input icon, Figure 1) as input to extract from them the timeseries corresponding  to a selected response unit. The User may select among "Displacement", "Velocity" and "Acceleration" from the tab next to "Response Unit" field as shown in Figure 1, and then click in the "Run" button (Blue button in Figure 1). 

Figure 1.

A new file has been now created and can be accessed by clicking on one of the two links shown in red frames in Figure 2:

Figure 2.

After this selection the window shown in Figure 3 appears in the screen. A interactive geographical map with the locations of the seismic network station depicted is demonstrated (see map views chapter). Moreover, the waveforms from the signals recorded by those stations (3 channels - E, N, Z) are available corresponding to the response unit (Displacement, Velocity, Acceleration) previously selected by the User (see Waveform Viewer chapter for waveform processing). The User can now use these waveform data for further analysis by selecting one of the available applications (actions) as shown in Figure 3.

Figure 3.

• Seismogram picking tool

Seismogram picking tool takes as input seed files. The service interface is identical to the one shown in Figure 3. Here the User can pick phases or points from the given waveforms (see Waveform Viewer Chapter). Ones the picks have been chosen the User may proceed to further analysis by clicking the blue "Run: button (Figure 4.). The number of picked phases are counted by the system. The User can now recall the output file (.xml, shown into the red frame, at the bottom of Figure 4), for any Waveform-based (Source Parameter Estimation) application (i.e. Moment Tensor Inversion, Earthquake Spectra, Source Location)  

Figure 4.

• Catalog Filter

This is a service for filtering seismic catalogs. The product is a new catalog filtered upon the User's parameters setting. The input file is a seismic catalog that can be uploaded from "Change Input" tab (shown in the yellow frame of Figure 5). Next, the User may perform various filtering according to the values of the attributes assigned in the catalog. The User may choose on of these attributes (as ID, ML, Lat etc, displayed in Figure 5) and provide the values he/she wishes, selecting among 'Select all values' (option "1", Figure 5), 'Select Range' (option "2", Figure 5) and 'Select list of values' (option "3", Figure 5).

Figure 5.

Alternatively, the User may apply interactively spatial filtering by clicking in the "Select events from map" tab (depicted by the red box in Figure 5). This is an interactive option providing to the User the possibility to select data, spatially constrained by a predefined shape (numbers 1-4 in Figure 6):

1) No draw option.

2) Draw a polygon.The User may select data into a polygon drawn after clicking in different points of the map. To close the polygon, the User has to double click on the last point, such that this point will be connected with the first one.

3) Draw a rectangle. To select data into a rectangular the User has to click at a point on the map and move the cursor at any direction. A second left mouse button click will restrict the selected area in its current state

4) Draw a circle (option demonstrated in Figure 6). To select data into a circular the User has to click at a point on the map and move the cursor at any direction. A second left mouse button click will restrict the selected area in its current state. Note that the first click on the map corresponds to the circle's center.

Figure 6.

As soon as the filtering criteria have been defined, the User shall click on the "Run" button (blue button at the bottom of Figure 5). The User may also select the "Preview Selection on map" tab in order to view an illustration of the events from the original catalog (red circles) and the events included in the filtered catalog (green circles). A new catalog (catalog.mat) has been created and it is available for the User for any further processing. In addition the system provides all the information and services that are valid for the original catalogs (see AH Episodes Chapter, for details).

• Coordinates Transformation

This Application is performed in order to transform the epicentral loation of the seismic events to a selected Cartesian Coordinate System (Note that epicentral location data available in IS-EPOS is given in geographical coordinates). The available types of coordinate systems are shown in Figure 7. Once the User makes the selection and clicks on the "Run" button, a new catalog is created, which contains all the data previously available in the original catalog, plus the seismic events epicentral location in the selected Cartesian system. The new catalog is stored in the system and is available for any further processing. In addition the system provides all the information and services that are valid for the original catalogs (see AH Episodes Chapter, for details). 

Figure 7.

• Magnitude Conversion

Magnitude Conversion is a service used for establishing linear relationships between different magnitude scales, which can be later used for conversion of magnitudes from one scale to another. The input file is the seismic catalog that can be uploaded from "Change Input" tab (shown in upper right part of Figure 8). The Service can be performed only in datasets where more than one magnitude scale is assigned for the seismic events (e.g. ML and Mw). The other parameters that the user has to set/choose are also shown in Figure 8:

Figure 8.

• Choose first vector to compare: The user may choose among the different magnitude scales provided by the catalog.
• Choose second vector to compare: The user may choose among the different magnitude scales provided by the catalog.
• Regression Method: Three different regression methods are available - General Orthogonal Regression, Standard Least Squares and Inverted Least Squares.
• Error Variance Ratio: A float number should be assigned here (default is 1). Note that this option is only valid for General Orthogonal Regression method.

The outputs of the service are:

•  A report with the results of the regression process and some statistics (Figure 8)
• Vectors of the first, second magnitude vectors selected, together with the vector with the new (converted) magnitudes obtained by the regression.
• A figure with one magnitude scale plotted versus the other one (scatter plot) and the linear regression curve (Figure 9). Zooming option is enabled for this figure.

Figure 9.

• FilterOverMmin

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• FilterWithinTime

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