Geophysics Department TU Clausthal

deutsch english Applied Geophysics : Geoelectrics


Electric Sounding


Applet    ( in separate window, ca. 370 x 120 Pixel )

DEMO-Version     PARAM-Version      ( see below : Applet Versions )


The applet calculates
apparent resistivity curves of geoelectrical resistivity sounding measurements
for layered subsurface models,
interactively adjustable to fit field observations.

In a separate window
model, resistivity curve and field observations are dispayed in a log-log scale.

At present, filters are implemeted for Schlumberger, Wenner and Dipole-Dipole (inline) field configurations.


Literature / Filter Coefficients

GOSH, D.P. :
The application of linear filter theory to the direct interpretation of geoelectrical resistivity sounding measurements.
Geophys. Prosp., 19(1971)2, p. 192.
KOEFOED, O. :
Geosounding Principles, 1 - Resistivity sounding measurements.
Elsevier Scientific Publishing Comp., 1979, 276 p.
NYMAN, D.C. and M. LANDISMAN :
VES dipole-dipole filter coefficients.
Geophysics, 42(1977)5, p. 1037.
O'NEILL, D.J. and N.P. MERRICK :
A digital linear filter for resistivity sounding with a geralized electrode array.
Geophys. Prosp., 32(1984)1, p. 105.
and (most useful to me)
WELLER, A. :
Geoelektrische Sondierungen - direkte und inverse Aufgabe.
Dissertation, Bergakademie Freiberg, 1989.
Prof. Dr. Andreas Weller, Institut fuer Geophysik der TU Clausthal )


Applet Versions

DEMO version :
Example data / models coded in program only, no local I/O

PARAM version :
Own field observations / models as applet parameters, no local I/O

FULL version :
Local I/O of own field observations / models included
( The utility policytool allows to enable an applet to access to the local disc,
for the appletviewer of JDK1.3.1_17 I was successful, for JDK1.5.0 read access only ? )

The "sand box" restrictions of Applets, especially in browsers as Netscape, Explorer etc.,
do not apply to applications running in a Java Runtime Environmet ( JRE ).
see Download

Top of Page    Mod / Dat Window    Graphics Window    Download


HOWTO


Applet / Dialogue window :
( Screenshot )

CONFIG : SCHLUMBERRGER / ...
selects a field configuration.

SAVE / REST MODEL
opens a window for I/O and listing of model parameters.

SAVE / REST DATA
opens a window for I/O and listing of field observations.

RESET ( Applet )
closes all windows and clears all model parameters and field observations,
EXIT ( Application ) :
exits the application.

GRAPHIC :

SHOW
shows a graphic display ( logi / log ) of selectable content :

MODEL
= layer boundaries and resistivities ( magenta ),
CURVE
= calculated apparent resistivity ( green ),
DATA
= field observations ( blue ),
DIFF
= ( CURVE - DATA ) x 10 ( cyan ),

ERMS
displays the r.m.s. error and the number of observations included.

AUTO SCALE
enables automatic scaling of the display window.

HELP
displays possible mouse interactions, dependent on the actual cursor position.
( Adjustment of display range, model parameters and field observations )

Top of Page    HowTo    Graphics Window    Download


Model window :
( Screenshot )

Data window :
( Screenshot )

In both windows :

Choice : CLEAR TEXT AREA, LIST ...

HIDE
closes the window.

Model window :

If LOAD MOD ... loads an example model,
approximate parameter values describe a starting model, to be adjusted to fit the corresponding example observations,
if HELP is activated,
the exact values ( used to calculate the synthetic observations ) are loaded.

Data window :

The example observations for SCHLUMBERGER und DIPOLE - DIPOLE are composed from
three overlapping segments, corresponding to different separations of the potential electrodes, and
shifted by a factor F-Step > 1 against the preceeding segment.

Example observations loaded LOAD DATA ...
contain approx. values F-Step, to be adjusted interactively,
if HELP is activated,
exact values are used.

Top of Page    HowTo    Mod / Dat Window    Download


Graphic window :
( Screenshot )

The "scrollbars" ( gray, above and left ) allow to adjust
legth and position of the horizontal and vertical display range ( marked white ).

In the model display ( magenta )
layer boundaries and resistivities can be adjusted,
boundaries can be removed or inserted.

In the display of field observations ( blue )
data segments can be shifted along the horizontal ( resistivity ) axes to fit the preceeding segment,
observations can be included in / excluded from the r.m.s. error calculation, setting their weight to 1 / 0.

The text field RAW INP ( lower left ) selects
the display of raw input data ( all shifts removed )
and disables shifting of segments.

HELPApplet / Dialog window ) displays
hints to possible mouse interactions in a text field ( yellow ).

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Download

Class files are available for :

the DEMO / PARAM version ( Applet )
incl. html-files, containing example PARAM tags for models and field obsevations
as a
zip file and as a .tar.gz file,

the FULL version ( Applet + Application )
incl. example files for model parameters and field observations
as a zip file and as a .tar.gz file.

The Java Runtime Environment ( JRE ) to run the Application
is available for several platforms at Sun Microsystems, Inc.

More applets at : the author's Homepage


Rev. 23-jan-2007

Comments to Fritz Keller
( ned gschempfd isch globd gnueg )

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