Mini Res

byRob Turner, Bridget Bliss, Scott Briscoe

Outline

• Methods

• Locations

• Characteristic curves

• Cumulative resistivity inversion

• Typical fault signature

• Results

Methods

• 2 Primary methods• Schlumberger• Wenner • Differences- Schlumberger you only have to

move the voltmeter electrodes as opposed to moving all 4. The Wenner method is the most time consuming but yields the best data. In this method you move all 4 posts.

• We used the Wenner method.

Fernley Locations

Hazen Location

Wenner Method

Characteristic curves

• We created characteristic curves for the Hazen area and the Fernley area.

• The curves can be matched to the Schlumberger two-layer type curves to determine the relative resistivity of the lower layers compared to the upper layers.

Fernley Characteristic Curves

Hazen Characteristic Curves

Schlumberger Two-layer Type Curves

Fernley Inversion

Hazen Inversion

Typical fault signatureGouge Zone

Strike slip fault

Fernley EM Profile 1 Data vs. Elevation

4100

4200

4300

4400

4500

4600

4700

4800

4900

4,380,800 4,381,300 4,381,800 4,382,300 4,382,800 4,383,300

Northing

Fee

t

0

50

100

150

200

250

300

Ap

par

ent

Res

isti

vity

(o

hm

-m)

Elevation

EM

Fernley EM Profile 2 Data vs. Elevation

4100

4200

4300

4400

4500

4600

4700

4800

4380500 4381000 4381500 4382000 4382500 4383000

Northing

Ele

vati

on

0

50

100

150

200

250

Ap

par

ent

Res

isti

vity

(o

hm

-m)

Elevation

EM

Hazen Flats EM vs. Elevation

4040

4060

4080

4100

4120

4140

4160

4180

4200

4220

4240

4260

4375500 4376000 4376500 4377000 4377500 4378000 4378500 4379000 4379500

Northing

feet

0

50

100

150

200

250

300

350

400

450

Ap

par

ent

Res

isti

vity

(o

hm

-m)

Elevation

EM

Results

• Apparent resistivities obtained in this study are indicative of clays (1-100 ohm-m) or sands (1-1000 ohm-m)

• The Fernley data are more indicative of sands

• The Hazen data are more indicative of clays

• Anomalies may indicate groundwater, sedimentary structures or disturbed zones

Conclusions

• The data do not conclusively prove or disprove the presence of a fault

• Data integration is the key to accurately analyzing this data