By Dr. David W. Barber
Geoscience, the study of the Earth, its composition, structure, and processes, enables us to better understand its history, past, present, and future. The purpose of these studies include exploration, extraction and wise management of commercial resources, protection and preservation of the environment, and protection from and prevention of geologic hazards. These studies involve both the surface and subsurface of the Earth and require both direct and indirect measurements of the pertinent factors at work. The complexity of the issues encountered in earth science, the interconnectivity of natural and man-made processes, and the variable data sets involved in their study, provide geoscientists many intriguing but challenging problems to be solved and communicated effectively to their colleagues and to the public.
The basic tools of geoscientists start with their personal skills and aptitudes. Observational skills are especially valuable for the geoscientist who desires to engage in field studies or laboratory experiments that recreate the geologic process being studied. However, those skills also help in the interpretation and integration of the diverse data sets that occur frequently in practice. Critical thinking and problem solving skills are always valuable in geoscience studies, especially the ability to think “outside the box”. Because most studies involve interdisciplinary participation, interpersonal skills are very important to facilitate mutual interactions with colleagues and managers. Finally, communication skills help the geoscientist to write reports and research papers to disseminate the results of the study to the people who would benefit from them.
Field studies are the backbone of geoscience; “the present is the key to the past”, a basic tenet. Therefore, from the past through the present becomes the pathway to the future. Field studies begin at the surface where soils, rocks and water are exposed and can be sampled and measured directly and the processes that affect them can be studied as they occur naturally. Samples acquired in the field can be studied in more detail in the lab through making thin sections of the rock which can be studied with microscopes or by subjecting the samples to chemical and X-ray analysis to determine their composition. Results from an accessible field location can be extended to inaccessible areas through remote sensing aerial photography and satellite imagery. The better we understand the surface of the earth, the better we will understand its interior.
The study of the interior of the earth uses primarily indirect observations; the most direct measurements are provided by mining operations and the drilling of wells for water or petroleum reserves. By far the most data about the nature of the interior comes from borehole instruments that directly measure the properties of the formations and fluids encountered by the borehole. These measurements can be extended to undrilled areas by seismic profiles generated by geophysical surveys that utilize compressional and shear waves propagated through the subsurface and recorded by sensors on the surface. The seismic reflections can be analyzed through signal processing methods to provide a picture of the orientation and distribution of the rock formations encountered by the wellbore. These methods have been used to explore for and produce hydrocarbons from petroliferous basins around the world, but these wells are concentrated where profitable reserves have been located and are limited in the depth they have penetrated. Deep wells for scientific purposes alone are few and far between.
Most of our knowledge about the interior of the Earth has come from geophysical studies of earthquakes, especially the powerful, deep-seated ones that are generated by descending oceanic plates which produce seismic signals that travel through the interior and can be analyzed by the same signal processing methods that produce seismic profiles in the near surface arena. Sophisticated methods for measuring heat flow in the mantle are also available as well as gravity meters which measure small variations in the ever-changing gravity field of the earth. The earth’s magnetic field can be measured to find out how it is changing today, and coring methods in the oceanic crust have revealed that the magnetic field has switched polarity multiple times during the spreading apart of the Atlantic plate. The causes of these variations in the basic properties of the Earth through time are mysteries that remain to be discovered.
Two additional tools promise great benefits to the geoscientist; one has already been mentioned in passing and one has been indirectly referred to. Satellite imagery has increased in capacity and capability as more and more satellites are being positioned around the globe and their measuring ability continues to increase. They are being used to measure the behavior of ocean currents, rise and fall of land elevations and the small lateral movements of the crust prior to a major earthquake. Synchronous orbits allow a satellite to remain over the same area of the Earth to study in minute detail its behavior over time. From climate change to earthquake prediction, these satellites offer tremendous opportunities to study these phenomena with greater accuracy than ever before.
The second tool, computer technology, has enabled technological leaps in multiple fields of study but especially in geoscience. It has allowed the integration and interpretation of seismic signals from large arrays of sources and receivers to produce detailed 2D and 3D seismic profiles with great precision and provides a great tool to analyze, interpret and project large data sets created by geoscientific studies. In addition, the advances being made in artificial intelligence have allowed computers to model the possible causes of the anisotropic behavior observed in the inner core as earthquake waves pass through it. Computers today can effectively model the behavior of the Earth through finite element analysis, and their increase in computational power allows them to analyze more complex problems.
Technology continues to develop rapidly, even exponentially. With bore logging geologists can also use well log analysis software which helps enable the documentation of application log files for records and analytics.
As the number of tools available to the geoscientist has increased dramatically in the last 100 years, it is sure to increase still faster in the future. And we have just begun studying the other objects in our solar system!
