Supplementary information to : “ Radon emanation and electric potential
variations associated with transient deformation in the vicinity of reservoir
lakes ”, by M. Trique, P. Richon, F. Perrier, J.P. Avouac & J.C. Sabroux.
Table listing the lack of correlation or the correlation between the rainfall or snow
melting periods and the negative electric transient signals (amplitude > 5mV) or between
the rainfall and snow events and the radon anomalies (amplitude > 2000 Bq.m-3). If a
correlation is observed, the time delay between the meteorological event and the geophysical
anomaly is also indicated. We note that only the snow fall periods are not taken into account
for electric potential variations, since they do not directly provide water in the subsurface.
Meteorological events
Date
Type
16/11/95
21/11/95
16/12/95
22/12/95
09/01/96
06/02/96
21/02/96
25/02/96
21/03/96
03/04/96
05/04/96
27/04/96
07/05/96
15/05/96
18/05/96
23/05/96
31/05/96
07/06/96
19/06/96
30/06/96
22/07/96
26/07/96
31/07/96
04/08/96
09/08/96
18/08/96
17/09/96
30/09/96
15/10/96
20/10/96
27/10/96
17/11/96
04/12/96
Electrical transient signals
duration Time
Time
duration
(day)
correlation delay
(day)
(day)
Snow fall
2
X
Snow melt
6
No
Rainfall
3
Yes (2)
11
8
Snow fall
10
No
Snow melting 15
No
Snow fall
8
No
Snow fall
1
No
Snow melting 22
Yes (3)
26
24
Snow fall
1
No
Snow fall
1
No
Snow melting 23
No
Rainfall
7
No
Rainfall
6
No
Rainfall
2
No
Rainfall
4
No
Rainfall
6
No
Rainfall
3
No
Rainfall
5
No
Rainfall
8
No
Rainfall
9
Yes (4)
6
5
Rainfall
3
No
Rainfall
5
No
Rainfall
3
X
Rainfall
4
X
Rainfall
5
X
Rainfall
10
X
Rainfall
7
X
Rainfall
2
Yes (6)
19
33
Snow fall
2
No
Snow melting 2
No
Rainfall
3
No
Snow fall
13
no
Snow melting 7
no
-
1
Radon signals
Time
time
correlation delay
(day)
yes (1)
0
No
No
yes (2)
4
No
No
No
No
yes (3)
3
No
No
No
No
No
No
No
No
No
No
yes (4)
6
No
No
No
yes (5)
2
No
No
No
No
yes (6)
5
No
No
No
No
-
Duration
(day)
16
22
77
12
30
35
-
13/12/96
11/02/97
27/02/97
01/03/97
10/03/97
26/03/97
26/04/97
02/05/97
06/05/97
10/05/97
17/05/97
31/05/97
07/06/07
10/06/97
18/06/97
13/07/97
16/07/97
23/07/97
04/08/97
15/08/97
24/08/97
01/09/97
05/10/97
09/10/97
02/11/97
18/11/97
26/11/97
Snow fall
Snow fall
Snow fall
Snow melting
Snow fall
Snow melting
Snow fall
Snow melting
Snow fall
Snow melting
Rainfall
Rainfall
Rainfall
Rainfall
Rainfall
Rainfall
Rainfall
Rainfall
Rainfall
Rainfall
Rainfall
Rainfall
Rainfall
Rainfall
Rainfall
Rainfall
Rainfall
1
5
1
18
2
30
1
2
4
12
10
6
2
7
18
2
5
4
4
5
7
2
3
5
14
6
3
01/12/97
10/12/97
18/01/98
29/01/98
04/03/98
15/03/98
Snow fall
Snow fall
Snow fall
Snow melting
Snow fall
Snow melting
1
3
3
16
5
19
no
no
no
Yes (8)
no
yes
no
no
no
no
no
no
no
no
Yes (10)
yes
no
no
no
no
no
no
no
Yes (11)
yes
no
Yes (12)
yes
no
no
no
Yes (13)
no
no
4
23
2
1
4
8
14
45
19
-
17
2
15
3
13
5
X
7
12
-
yes (7)
No
No
yes (8)
No
No
No
yes (9)
No
No
No
No
No
No
yes (10)
No
No
No
No
No
No
No
X
Yes (11)
No
No
No
5
0
0
1
X
-
15
30
9
23
at least 10
-
No
yes (12)
No
yes (13)
No
No
4
21
-
38
44
-
N.B. : the symbol X signifies the lack of measurement, and the number (x) designates the
number of the anomaly reported in the figures of the present paper.
Table listing the lack of correlation or the correlation between the positive second
derivative applied on the lake level with a time period of 14 days and the negative
electric transient signals (amplitude > 5mV) or the radon anomalies (amplitude > 2000
Bq.m-3). If a correlation is observed, the time delay between the periods of accelerated
straining and the geophysical anomaly is also indicated.
Positive second derivative of the Electrical transient signals
lake level with T=14 days
Date
Type
Time
Time
Duration
Duration (day)
correlation delay
(day)
(day)
18/11/95 13
X
22/12/95 24
Yes (2)
5
8
10/03/96 94
Yes (3)
10
23
2
Radon signals
Time
correlation
yes (1)
yes (2)
Yes (3)
time
delay
(day)
-2
4
12
Duration
(day)
16
22
77
10/07/96
10/08/96
13/10/96
19/12/96
13/01/97
15/02/97
04/03/97
06/04/97
03/05/97
22/09/97
21/10/97
13/11/97
18/12/97
20/02/98
13
20
51
10
16
13
18
20
33
9
5
13
30
22
Yes (4)
X
Yes (6)
No
No
No
Yes (8)
yes
no
No
Yes (11)
yes
Yes (12)
Yes (13)
-3
6
0
2
-8
-1
-8
-2
5
33
17
5
13
5
X
12
Yes (4)
Yes (5)
Yes (6)
Yes (7)
No
No
Yes (8)
No
yes (9)
No
Yes
No
yes (12)
yes (13)
-3
1
7
-1
-4
-1
X
-4
0
12
30
35
15
30
9
at least 10
38
44
We can therefore evaluate the proportion of meteorological events or accelerated straining
periods, which could be correlated to the radon and electrical signals. These results can be
compared with the values obtained given random time series of radon or electrical signals. To
perform this evaluation, we fixed a maximum time delay of 10 days between the
meteorological events and the observed signals. Because the discrete second derivative, as
defined in the paper, could not reflect the instantaneous accelerated loading of the medium,
we allow the time delay between the accelerated loading and the radon or electrical signals to
range between -10 and 10 days. The results are presented in the following diagram.
3
Electrical signals
100
90
80
70
60
% 50
40
30
20
10
0
Observations
Random time serie
Meteorological
events
Accelerated
straining
Radon signals
100
90
80
70
60
% 50
40
30
20
10
0
Observations
Random time serie
Meteorological
events
Accelerated
straining
The correlation ratio between the meteorological events and the real electrical and radon
signals is similar to the same correlation ratio given random signals. This reflects the lack of
trivial and direct relation between the meteorology and the radon and electrical signals.
Moreover, the correlation ratio between the accelerated loading and the real electrical and
radon signals is significantly higher than the same correlation ratio given random signals.
Consequently, the radon and electric signals appear to be related to the periods of accelerated
straining, that means to the mechanical behaviour of rocks, although the meteorological origin
can not be undoubtedly rejected.
4