Podcast
Questions and Answers
What is the primary difference between active seismic and passive seismic?
What is the primary difference between active seismic and passive seismic?
Which statement accurately describes gravity surveys?
Which statement accurately describes gravity surveys?
What is the primary purpose of ground penetrating radar (GPR)?
What is the primary purpose of ground penetrating radar (GPR)?
How are well samples obtained in drilling operations?
How are well samples obtained in drilling operations?
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What aspect of seismic wave behavior provides information about subsurface materials?
What aspect of seismic wave behavior provides information about subsurface materials?
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What advantage do gravity and magnetic surveys offer?
What advantage do gravity and magnetic surveys offer?
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Which scenario demonstrates a limitation of ground penetrating radar (GPR)?
Which scenario demonstrates a limitation of ground penetrating radar (GPR)?
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Which of the following is NOT a use of magnetic surveys?
Which of the following is NOT a use of magnetic surveys?
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What is subsurface geology primarily concerned with?
What is subsurface geology primarily concerned with?
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What is the purpose of geotechnical reports?
What is the purpose of geotechnical reports?
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Which method is primarily used to obtain subsurface information?
Which method is primarily used to obtain subsurface information?
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What role do seismic surveys play in subsurface studies?
What role do seismic surveys play in subsurface studies?
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Which study is referred to when focusing on groundwater aquifers?
Which study is referred to when focusing on groundwater aquifers?
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What type of report is necessary for deep subsurface exploration?
What type of report is necessary for deep subsurface exploration?
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What information can drilling boreholes provide?
What information can drilling boreholes provide?
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What is a significant limitation of subsurface information collection methods?
What is a significant limitation of subsurface information collection methods?
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Study Notes
Subsurface Geology
- Subsurface geology studies the physical properties and location of rocks and soil below the surface.
- Shallow subsurface studies are called geotechnical reports, crucial for safe building construction and groundwater exploration in areas with geologic hazards.
- Deep subsurface studies are exploration reports, necessary for petroleum prospecting and development.
- Subsurface geologists use data to create resource maps, interpret geologic maps, understand structures like faults and folds, and make 3D models of geological settings.
Petroleum Exploration
- Subsurface geological methods are increasingly important in petroleum exploration and production.
- Growing demand for subsurface understanding leads to more specialists in this field.
Groundwater
- Subsurface studies are crucial for understanding and protecting groundwater aquifers to maintain water supplies.
- These studies help understand water flow, aquifer storage, and contaminant entry.
Subsurface Data Collection Methods
- Boreholes: Primary method for subsurface information. Drilling brings rock samples for on-site and laboratory study; tests can be done in open boreholes. Data includes material properties, rock variations, fault locations, and water/bedrock depths.
- Seismic Surveys: Analyze seismic waves reflected or refracted from subsurface layers. Active seismic uses generated waves (e.g., hammer, air-gun, or explosives); passive seismic uses natural waves. Surveys can be conducted on land or water, with varied depths (tens of feet to kilometers). Wave speed reveals layer composition and arrangement.
- Gravity and Magnetics: Often used together for subsurface characterization. Gravity surveys identify density differences in rock formations (useful for bedrock depth and basin basement depth). Magnetic surveys identify magnetic contrasts in rocks (useful for fault, fold, and magnetic mineral mapping). Ground or airborne surveys are possible, with ground data offering higher resolution. Combined analysis is needed.
- Ground Penetrating Radar (GPR): Images the subsurface using radar pulses. Similar to radio waves bouncing off an aircraft, radar signals bounce off subsurface layers, showing faults, contacts, and objects. Depth and resolution vary based on frequency and soil conditions. Typically depths are less than 100 feet.
- Well Cuttings: Samples produced from drilling operations. Samples at regular intervals establish a lithologic record and are plotted on a strip sample log.
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Description
This quiz explores the principles of subsurface geology, including its importance in construction, groundwater protection, and petroleum exploration. Understanding the physical properties and location of rocks and soil is crucial in various applications, particularly in creating resource maps and interpreting geological structures. Test your knowledge on key concepts and methodologies used in subsurface studies.
