Geophysical surveying and remote sensing

Geophysical Surveying

Introduction to geophysical surveying: Involves non-destructive techniques used to investigate subsurface features. It can reveal geological structures, mineral deposits, or archaeological remains without any drilling, digging or probing.
Seismic Surveys: Used to investigate the structure of the Earth’s crust. Vibrations are set off on the surface and their reflections from different layer boundaries are recorded.
Gravity Surveys: These measure the variations in the Earth’s gravitational field, which can provide information about the density of subsurface rocks.
Magnetic Surveys: Record variations in the Earth’s magnetic field. This data can provide information about the magnetic properties and distribution of rocks.
Electrical Resistivity Surveys: Measure resistance to the flow of electricity. This information identifies differences in the subsurface rock or soil types.
Ground-Penetrating Radar (GPR): Works by sending a pulse of high frequency radio waves into the ground and analysing the echoes returned.
Interpretation of data: Evaluation of these survey results to understand the underground geological conditions is a critical skill, one guided by principles in physics and mathematics.

Remote Sensing

Remote sensing basics: Refers to methods of collecting data or information about an object or phenomenon without coming in physical contact with it. Often involves the use of satellite- or aircraft-based devices.
Satellite Imagery: Images taken by satellites can provide an overall large-scale view of an area. This can reveal features such as tectonic boundaries, geological structures, or even impact craters.
Thermal Imaging: Emits infrared waves that can detect variations in temperature. Can be used to identify volcanic activity or groundwater flows.
Lidar (light detection and ranging): Uses light in the form of a pulsed laser to measure distances. Can be used to produce high-resolution maps of the topography and features of the Earth’s surface.
Spectroscopy: Studies the interaction between matter and electromagnetic radiation. In geology, it is used to identify minerals and types of vegetation.
Photogrammetry: The science of measuring physical objects from photographs from either the ground or the air.
GIS (Geographic Information System): A system used for capturing, storing, checking, and displaying data related to positions on Earth’s surface. It can manipulate geophysical data to create three-dimensional images, maps and other visual products.
Data interpretation: Understanding and drawing conclusions from remote sensing data is one of the most important aspects of geological investigation. It depends on understanding of geography, geology, physics, as well as technical details of the sensors and platforms.