Refraction Survey

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Exploration Technique: Refraction Survey

Exploration Technique Information
Exploration Group: Geophysical Techniques
Exploration Sub Group: Seismic Techniques
Parent Exploration Technique: Active Seismic Techniques
Information Provided by Technique
Lithology: Rock unit density influences elastic wave velocities.
Stratigraphic/Structural: Can provide information on crustal thickness, depth to basement.
Hydrological:
Thermal:
Cost Information
Low-End Estimate (USD): 6,206.80620,680 centUSD
6.207 kUSD
0.00621 MUSD
6.2068e-6 TUSD
/ mile
Median Estimate (USD): 10,877.331,087,733 centUSD
10.877 kUSD
0.0109 MUSD
1.087733e-5 TUSD
/ mile
High-End Estimate (USD): 25,000.002,500,000 centUSD
25 kUSD
0.025 MUSD
2.5e-5 TUSD
/ mile
Time Required
Low-End Estimate: 12.73 days0.0349 years
305.52 hours
1.819 weeks
0.418 months
/ 10 mile
Median Estimate: 36.18 days0.0991 years
868.32 hours
5.169 weeks
1.189 months
/ 10 mile
High-End Estimate: 115.27 days0.316 years
2,766.48 hours
16.467 weeks
3.787 months
/ 10 mile
Additional Info
Cost/Time Dependency: Energy Source Needed, Source and Receiver spacing, Terrain, Size
Dictionary.png
Refraction Survey:
Seismic refraction surveys image the structure of the subsurface through the measurement of p-wave first arrivals from refracted elastic waves.
Other definitions:Wikipedia Reegle






 
Use in Geothermal Exploration
Seismic refraction may be applied toward geothermal exploration through the generation of crustal thickness maps on a regional scale. Crustal thickness is significant because heat flow may be higher in regions with thinner crust. Gaining an understanding of regional crustal thickness, in conjunction with other data sets such as gravity, temperature gradient data, fault location or strain rate data, enables an understanding of the factors related to the occurrence of a geothermal system. [1]

The image below is a crustal thickness map of the Great Basin, compiled from three long-range seismic refraction surveys. The North Walker Lane and Idaho-California-Nevada transects are shown as small black triangles on the figure. The colored circles indicate other data sets which were integrated into the crustal thickness map. In this particular example, both active and passive sources were utilized: the Barrick GoldStrike 232 blast, and the M 2.8 Paso Robles, CA earthquake. The scale ranges from ~20-55 km depth with blue representing thicker crust and red showing thinner crust.[1]

Great Basin crustal thickness map interpreted from seismic refraction data. [1]

 
Field Procedures
See Active Seismic Techniques, Passive Seismic Techniques

The field procedures for a seismic refraction survey are similar to a seismic reflection survey; the main difference is that a refraction survey requires a greater source-receiver distance to measure the refracted wave.
 
Environmental Mitigation Measures
 
Physical Properties
See Seismic Techniques

The figure below shows a simplified representation of the ray path geometry of a refraction survey.[2]

Schematic of seismic refraction geometry.[2]

 
Data Access and Acquisition
See Active Seismic Techniques, Passive Seismic Techniques

Seismic refraction configures the source/receiver array such that the seismic wave travel is along the target of the survey. In general, the p-wave first arrivals are recorded with a refraction survey. The frequency of the refracted signals is lower than in a reflection survey because of the greater source-receiver distance. [3]
 
Best Practices
See Active Seismic Techniques, Passive Seismic Techniques

• Refraction profiles should be five to ten times the length of the required depth of investigation in order to treat refracted events as first arrivals. [3]
 
Potential Pitfalls
• Imaging to depths greater than a few kilometers with a refraction survey may be problematic because the profile length for the geophone array must be at least five times the desired depth of investigation. [4]

• Areas which host geothermal systems are generally geologically complex and this complexity may create complications for a refraction survey. [4]









Page Area Activity Start Date Activity End Date Reference Material
Refraction Survey (Laney, 2005) Unspecified


Refraction Survey At Central Nevada Seismic Zone Region (Heimgartner, Et Al., 2005) Central Nevada Seismic Zone Geothermal Region


Refraction Survey At Chena Geothermal Area (Wescott & Turner, 1982) Chena Geothermal Area 1979 1980


Refraction Survey At Coso Geothermal Area (1989) Coso Geothermal Area 1989 1989


Refraction Survey At Hot Sulphur Springs Area (Laney, 2005) Hot Sulphur Springs Area


Refraction Survey At Kilauea East Rift Geothermal Area (Broyles, Et Al., 1979) Kilauea East Rift Geothermal Area 1976 1977


Refraction Survey At Kilauea East Rift Geothermal Area (Leslie, Et Al., 2004) Kilauea East Rift Geothermal Area 1998 1998


Refraction Survey At Kilauea East Rift Geothermal Area (Thomas, 1986) Kilauea East Rift Geothermal Area 1978 1987


Refraction Survey At Kilauea Summit Area (Chouet & Aki, 1981) Kilauea Summit Area


Refraction Survey At Mt Princeton Hot Springs Geothermal Area (Lamb, Et Al., 2012) Mt Princeton Hot Springs Geothermal Area 2012 2012


Refraction Survey At New River Area (DOE GTP) New River Area


Refraction Survey At North Brawley Geothermal Area (Fruis & Kohler, 1984) North Brawley Geothermal Area 1979 1979


Refraction Survey At Northern Basin & Range Region (Heimgartner, Et Al., 2005) Northern Basin and Range Geothermal Region


Refraction Survey At Nw Basin & Range Region (Laney, 2005) Northwest Basin and Range Geothermal Region


Refraction Survey At Roosevelt Hot Springs Geothermal Area (Ward, Et Al., 1978) Roosevelt Hot Springs Geothermal Area 1978 1978


Refraction Survey At Rye Patch Area (Feighner, Et Al., 1999) Rye Patch Area


Refraction Survey At Rye Patch Area (Laney, 2005) Rye Patch Area


Refraction Survey At San Emidio Desert Area (DOE GTP) San Emidio Desert Area


Refraction Survey At Snake River Plain Region (DOE GTP) Snake River Plain Geothermal Region


Refraction Survey At Walker-Lane Transitional Zone Region (Heimgartner, Et Al., 2005) Walker-Lane Transition Zone Geothermal Region


Refraction Survey At Walker-Lane Transitional Zone Region (Laney, 2005) Walker-Lane Transition Zone Geothermal Region


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