The characteristics of geoelectric fields at Kakioka, Kanoya, and Memambetsu inferred from voltage measurements during 2000 to 2011

Earth, Planets and Space

Table 1 Details of the geoelectric voltage observations at Kakioka from 1932 to the present

	Start date	Coordinate	Length (m)	Electrode
	Start date	Coordinate	Length (m)	Type	Size (m × m)	Number/site	Depth (m)
N-S line	1 August 1932	M	100	Cu	0.7 × 0.7	2	3
	1 August 1933	M	1,120	Cu	1 × 1	2
	5 May 1937	M	1,040	Cu	1 × 1	2
	10 January 1944	M	895	Cu	1 × 1	2
	1 August 1948	M	900	C	0.3 × 0.05	2
	1 February 1988	G	180	Pb-PbCl₂	0.2 × 0.05	1	4 to 1.5
	1 September 1990	G	300	Pb-PbCl₂	0.2 × 0.05	1	~3
	1 July 1991	G	180	Pb-PbCl₂	0.2 × 0.05	1	~3
	1 September 1992	G	180	Cu	1 × 0.5	1	~3
E-W line	1 August 1932	M	100	Cu	0.7 × 0.7	2	3
	1 August 1933	M	1,500	Cu	1 × 1	2
	1 March 1983	M	1,200	Cu	1.4 × 0.4 (W)	2	~3
	1 February 1988	G	190	Pb-PbCl₂	0.2 × 0.05	1	4 to 1.5
	1 January 1993	G	190	Cu	1 × 0.5	1	~3

The terms ‘N-S line’ and ‘E-W line’ denote the north–south and east–west measurement lines along which the geoelectric voltages are observed, respectively. M and G in the ‘Coordinate’ column denote the geomagnetic and geographic coordinate systems, respectively, which are used for electrode alignment. The electrode type is represented by either Cu (copper plate), C (carbon rod) or Pb-PbCl₂ (pod with a Pb wire covered with PbCl₂). The number per site for each electrode states how many plates or rods are combined to form an electrode at the end of the measurement line. ‘W’ in the ‘Size’ column indicates that the listed electrode size is for the electrode at the western end, which was replaced in 1983.