Resistivity Results

GPH 492 Spring 2013 Schurz, NV

Field MapBox 1

Box 2Box 3

Model Types

Q-type: Decreasing apparentresistivity with depth

H-type: Layer 2 apparent resistivity is less than layer 1 and layer 3

K-type: Layer 2 apparent resistivity is greater than layer 2 and layer 3

A-type: Increasing apparent resistivity with depth

Plot of Apparent Resistivity vs. A-Spacing

0.35 3.50 35.0050

500

Box 1

Location 1 western red square 1 on fault fault-parallelLocation 1 western red square 1 on fault fault-normalLocation 2 western red square 1 NE of fault fault-parallelLocation 2 western red square 1 NE of fault fault-normalLocation 3 western red square 1 SW of fault fault-parallelLocation 3 western red square 1 SW of fault fault-normal

a-spacing, m

rho,

ohm

-m

0.35 3.50 35.0050

500

Box 2

Location 4 middle red square on fault fault-parallel

Location 4 middle red square 1 on fault fault-normal

Location 5 middle red square 1 NE of fault fault-parallel

Location 5 western red square 1 NE of fault fault-normal

Location 6 western red square 1 NE of fault fault-parallel

Location 6 western red square 1 SW of fault fault-normal

a-spacing, m

rho,

ohm

-m

Plot of Apparent Resistivity vs. A-Spacing

Box 2

• Most profiles yield shallow high resistivity layer at the surface of less than 2 m

• Low resistivity layer at depth ranges from 4.5 to 40 m

• Range of imaginary component values is 0.01 to 0.33 ohms

• Depth of confidence of arrays: 20 meters

Box 3, all arrays parallel to fault trace

-all arrays (except 8 and 10) showed a thin low resistivity layer at a shallow depth-Depth of the 1st layer varied from ½ - 2 m, with one plot reaching 6.4 m, resistivity varied from 161 – 319 ohm-m.-All arrays were H or K-type models, 2 arrays could not be modeled with a RMS values less than 100.-The depth of confidence was between 1-3 m, this is probably too shallow to see a fault

0 50 100 150 200 250 300 350 400 450 5000

100

200

300

400

500

600

Box 3. 3.16 m A-spacing resistivity (ohm-m) vs loca-tion, southwest to northeast (m)

L11 - L14L7 - L11

meters northeasting

Resis

tivity

(ohm

-m)

Box 3 Imaginary Component error

Sources of error

• Metal spiked rod electrodes not completely grounded

• Electrodes not placed at exact A-spacing values

• Sand and Clay layers in Box 3• Open line in array; electrodes moved

perpendicular from array

Conclusions

• We believe we found a low-resistivity anomaly at depth indicating possible location of fault in Box 1

• Box 2 and 3 did not exhibit similar anomaly as in Box 1

• May have missed the fault trace in Box 2