GPR Velocity

The GPR Velocity for concrete, clay, sand, limestone, loam, ice, and granite is not always well defined. The table of GPR velocities, dielectric constants, and conductivity values is a culmination of resources comparing values reported by government agencies and sources easily accessed by the public. The chart is intended to provide a comparison of how the GPR velocity of a material can range between sources.

GPR Velocity Table Selection

GPR velocity selection shown on a Sensors & Software DVL400 with a Utility SmartCart

It is not unexpected that different sources report different values of GPR velocity for like materials because clay, sand, concrete, and other materials listed in the table are dependent on a material’s conductivity and relative permittivity (dielectric properties (K)). Values of conductivity and relative permittivity are often a function of a material’s density, porosity, moisture content or saturation, pore fluid conductivity, and temperature. In addition, the relative permittivity of a material can vary with the frequency of the transmitted electromagnetic pulse passing through the material. Thus, the GPR velocity of a material can vary with different frequency antennas.

GPR Velocity Table and Analysis of Velocity,
Dielectric Constants, Attenuation, and Conductivity Values for
Materials From Various Sources

 (Multiple entries reflect different references. Values
are obtained from internet sites and other sources open to the public. This chart does not
validate if the GPR velocity, dielectric constants, attenuation, or
conductivity values are good representations of the material described.)

MATERIAL

DIELECTRIC
CONSTANT K

CONDUCTIVITY
(mS/m)

GPR VELOCITY
(m/ns)

GPR VELOCITY
(ft/ns)

ATTENUATION
(dB/m)

Air

1

0

0.3

0.98

Air

0.31

1.00

Air

1

0

0.3

0.98

Air

1

0

0.3

0.98

0

Air

1

0

0.3

0.98

0

Air

1

0

Asphalt

3 to 5

0.173 to
0.134

0.57 to
0.44

Asphalt

0.14

0.44

Asphalt (dry)

3

.001 to
.01

Asphalt (wet)

9

.01 to .1

Basalt (Wet)

0.11

0.33

Bauxite (Dry)

0.06

0.20

Clay (Dry)

0.15

0.50

Clay (saturated freshwater)

8 to 12

.09 to
0.11

0.28 to
0.35

Clay (wet)

8 to 12

100 to
1000

0.106 to
0.087

0.35 to
0.29

Clay (Wet)

0.06

0.19

Clay (wet)

10

100 to
1000

Clayey Soil (dry)

2.4

0.27

Clayey Soil (wet)

15

50

Clays

5 to 40

2 to 1000

0.06

0.2

1 to 300

Clays

5 to 40

2 to 1000

0.06

0.2

1 to 300

Coal

4 to 5

0.15 to
0.134

0.49 to
0.44

Coal

0.14

0.50

Concrete

5 to 10

0.134 to
0.095

0.44 to
0.31

Concrete (Dry)

0.13

0.44

Concrete (dry)

7

.001 to
.01

Concrete (Wet)

0.09

0.29

Concrete (wet)

15

0.01 to
0.1

Dolomite

6 to 8

0.122 to
0.106

0.40 to
0.35

Dry Salt

0.13

0.40

Dry Salt

5 to 6

0.01 to 1

0.13

0.43

Dry Salt

5 to 6

0.01 to 1

0.13

0.43

.01 to 1

Dry, sandy, flat coastal land

10

2

0.095

0.31

Dry, sandy, flat coastal land

10

0.09

0.31

Granite

4 to 6

0.01 to 1

0.13

0.43

0.01 to 1

Granite

4 to 6

0.01 to 1

0.13

0.43

0.01 to 1

Granite (dry)

5

0.00001

0.134

0.44

Granite (Dry)

0.14

0.44

Granite (Wet)

0.12

0.40

Granite (wet)

7

1

Ice

0.15

0.50

Ice

3 to 4

0.01

0.16

0.52

Ice

3 to 4

0.01

0.16

0.52

0.01

Ice

4

1

Ice Fresh Water

4

0.1 to 10

0.15

0.49

Limestone

4 to 8

0.5 to 2

0.12

0.39

0.4 to 1

Limestone

4 to 8

0.5 to 2

0.12

0.39

0.4 to 1

Limestone (dry)

7 to 9

0.000001

0.113 to
0.1

0.37 to
.33

Limestone (Dry)

0.13

0.44

Limestone (dry)

7

0.11

0.37

Limestone (Wet)

0.11

0.36

Limestone (wet)

8

25

Loamy Soil (dry)

2.5

0.11

Loamy Soil (wet)

19

21

Loamy/Clayey Soils (Dry)

0.19

0.67

Mineral/Sandy Soils (Dry)

0.13

0.40

Mixed soil components saturated

5 to 15

0.08 to
0.13

0.25 to
0.44

Organic Soils

0.04

0.13

Peats

0.04

0.13

Permafrost

4 to 8

0.01 to
10

0.15 to
0.106

0.49 to
0.35

Permafrost

6

0.01 to
10

Permafrost Frozen Soil

0.13

0.40

Potash Ore

0.13

0.44

PVC, Epoxy, Polyesters, vinyls, rubber

3

0.173

0.57

Quartz

4

0.15

0.49

Rock (dry)

5

0.00001

Sand & Gravel (Dry)

0.13

0.44

Sand & Gravel Frozen

0.14

0.44

Sand (dry)

4 to 6

0.0001 to
1

0.15 to
0.12

0.49 to
0.39

Sand (Dry)

0.15

0.50

Sand (Dry)

3 to 5

0.01

0.15

0.49

0.01

Sand (Dry)

3 to 5

0.01

0.15

0.49

0.01

Sand (dry)

4.5

0.0001 to
1

Sand (dry)

4 to 6

0.12 to
0.15

0.40 to
0.49

Sand (dry) Quartz

1.8 to 6

0.12 to
0.22

0.40 to
0.73

Sand (saturated freshwater)

30

0.05

0.18

Sand (wet)

25

0.1 to 1

0.055

0.18

Sand (Wet)

0.08

0.27

Sand (Wet)

20 to 30

0.1 to
1.0

0.06

0.2

0.03 to
0.3

Sand (wet)

25

0.1 to 10

Sand (wet) Quartz, and kaolinite, illite and smectite clays,
saturated freshwater

9 to 67

0.04 to
0.10

0.12 to
0.33

Sand and mixed soil components, dry

2 to 6

0.12 to
0.21

0.40 to
0.69

Sand Saturated

0.06

0.20

Sand Saturated

20 to 30

0.1 to
1.0

0.06

0.2

0.03 to
0.3

Sandstone (Wet)

0.13

0.40

Sandstone (wet)

6

40

Sandy Soil (dry)

2.6

0.14

Sandy Soil (wet)

25

6.9

Sandy Soils (Wet)

0.06

0.21

Sea Ice

4 to 12

0.15 to
0.087

0.49 to
0.29

Sea Water

70

400

0.033

0.11

Sea Water

80

3000

0.01

0.03

1000

Sea Water

80

3000

0.01

0.03

1000

Sea Water

81

4000

Sea Water

81

0.03

0.11

Shale

5 to 15

1 to 100

0.09

0.3

1 to 100

Shale (wet)

7

100

Shales

5 to 15

1 to 100

0.09

0.3

1 to 100

Silt (saturated)

10

0.09

0.31

Silt (wet)

10

1 to 10

0.095

0.31

Silt (wet)

10

1 to 100

Silts

5 to 30

1 to 100

0.07

0.23

1 to 100

Silts

5 to 30

1 to 100

0.07

0.23

1 to 100

Snow

0.25

0.80

Snow

1.4

0.001 to
0.01

Syenite Porphyry

0.13

0.40

Tills

0.09

0.31

Travertine

0.11

0.36

Volcanic Ash

0.09

0.29

Water

0.03

0.11

Water Distilled

80

0.01

0.033

0.11

0.002

Water Distilled

80

0.01

0.033

0.11

0.002

Water Fresh

81

0.10 to
30

0.033

0.11

Water Fresh

81

0.03

0.11

Water Fresh

80

0.5

0.033

0.11

0.1

Water Fresh

80

0.5

0.033

0.11

0.1

Water Fresh

80

0.5

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