Shot/Receiver (SR) Setup

The first step in 3D analysis is to set up spatial (X and Y) configuration of shot/receiver (SR) patterns into each of the acquired multichannel field records (i.e., SR setup).  Encoding these X-Y coordinates during field acquisition is almost prohibitive because most of engineering seismographs do not provide such options.  There are two ways to accomplish the SR setup in ParkSEIS. One is to use a Cartesian coordinate system adopted during the field operation and therefore logged in the field notes. This information can be prepared in a text file (*.txt) by using a simple format; for example, channel#, X, Y for receivers and record#, X, Y for shot points.  Another is to use GPS coordinates saved for all shot and receiver locations (e.g., *.gpx).

ParkSEIS-3D provides a highly convenient graphical-user-interface (GUI) for shot/receiver (SR) setup, which can be accomplished simply by importing two files prepared for receivers and shot points in the form of either Cartesian (*.txt) or GPS (*.gpx) format as illustrated in the first image below. The 3D grid can also be created from multiple 2D and/or 1D surveys as illustrated below. Multiple 2D velocity (Vs) cross sections can be imported by specifying surficial trajectories either by using mouse or by importing location files (*.txt or *.gpx) as illustrated in the second image below. Multiple 1D profiles can also be added in the same way.

From Dedicated 3D Survey

First, multiple field files (records) are imported by clicking "Import SEG-2 Files" button in the left-side panel. Then, click "Import Receiver Array" button that enables to select a Cartesian coordinate file (*.txt) or a GPS coordinate file (*.gpx). In the latter case, a reference point (e.g., 1st channel) will have to be specified on the map, and then all others will be accordingly makred on the map by calculating the relative coordinates. Click "Import Shot Array" to import a file for all shot points. The same procedure used in receiver setup will be used (e.g., *.txt or *.gpx) to complete the shot-point setup. Click "RUN SR SETUP" button to start encoding the appropriate SR coordinates into each of the imported field files and save all of them as one output file [*(3DSR).dat].

From Multiple 2D/1D Surveys

Click "Import 2D Cross Section" button to select a velocity (Vs) cross section file [*(2DVs).txt]. Then, using mouse, draw a line on the map to specify the line location and orientation. Or, you can choose a separate file (e.g., *.txt or *.gpx) fro this purpose that will replace the manual specification by using mouse. To add a 1D velocity (Vs) profile, click "Import 1D Profile" button and select a file [*(1DVs).lyr]. The location can be specified either manually (using mouse) or through an imported file (*.txt or *.gpx).

When all specifications are complete, save them as a project file (*.PJT), and then select "GRID" tab in the right-side panel where options are available to make a 3D velocity (Vs) grid data file (*.G3D) that can be displayed in the "Display 3D" tab.