What are the best geological surveying tools for mapping underground structures?

No doubt seismic methods are most reliable methods for monitoring subsurface features from few meters to kilometres. It’s cost effective and environment friendly than conventional drilling methods.

It is the most powerful means to understand underground structure, I have known. It is helpful for underground water, oil or other resources. And it is helpful for any underground foundations.

True, lseismic reflection is an effective method for underground investigations. However a balance should be striken between cost and benefit. So many times the cost surpurses the benefits associated. Thanks to emerging technologies. Electroseismics is proving to be highly effective and hence a need for more research and development of the method.

For deeper subsurface mapping, Seismic Reflection and Refraction methods are commonly employed. These techniques can image structures hundreds to thousands of meters deep, effectively identifying stratigraphy, faults, and resource deposits. However, they require substantial data processing, making them costly and complex to deploy.

Seismic data acquistion is a technique employed to delineate subsurface structures by transmitting seismic waves into the ground and analyzing the returning reflections. Sources such as dynamite charges or vibroseis trucks, seismic waves are generated and captured by geophones and nodes. By measuring the two-way travel time of these reflected waves, geophysicists can infer the depth, stratigraphy, and morphology of underground geological formations, aiding in the exploration of hydrocarbon reservoirs and other subsurface resources.

GPR, an effective method for the above mentioned investigations.Effective for near surface investigations and mostly give us unique results. The method is affected by ground conditions, eg moisture levels of the ground will affect the penetration depth. Alternative methods which map to depth and least affected by ground conditions like magnetotellurics do exist. The tellurics method may miss the few early depths. Problem of the method no unique results, so results rely on the power of the interpreter. The two methods complements each other well. Tellurics results can be calibrated by GPR results using the two methods common depth of investigations results.

Ground Penetrating Radar (GPR) is highly effective for shallow subsurface mapping. It provides high-resolution imaging, making it suitable for detecting non-metallic objects, material changes, and voids. However, its penetration depth is limited to about 30 meters, and its effectiveness diminishes in clay-rich or highly conductive soils.

In mineral exploration, magnetic gradiometry helps identify magnetic anomalies associated with ore deposits. Different minerals can exhibit varying magnetic properties, allowing geologists to map potential mineralization zones. Geophysicists use magnetic gradiometry to map geological structures, such as faults, folds, and igneous intrusions, which can affect mineralization and hydrocarbon accumulations. It provides insights into the subsurface geological framework.

Electrical Resistivity Tomography (ERT) is versatile for shallow to moderately deep investigations. It excels in mapping groundwater, contamination plumes, and voids, performing well in various soil conditions. Nonetheless, interpreting ERT data can be challenging, and its resolution decreases with depth.

This is an old technique that is the basis for the first wireline logging tools. It's as useful now as it was in the early 20th century. The depth of investigation is controlled by the emitter-to-receiver spacing making it very useful, even in the 21st century.

All methods of exploration are important and useful in respect of individual mineral commodities and their need/demand.Hence it is very important for mining stakeholders to review which kind of minerals are to be explored. Therefore suitable probing/ exploration methods could be utilised.

Our company has been doing Air-FTG surveys for over 20yrs and has delivered fantastic value to our clients with our gravity gradiometry surveys, helping to map out subsurface structures.

Gravimetry is particularly useful for identifying large-scale geological structures like oil reservoirs and mineral deposits. While it offers the advantage of detecting significant subsurface density variations, it provides low resolution and requires extensive data processing and interpretation.

Borehole studies are costly methods but provide better insitu information. But it has its own technical as well as administrative issues.

in my opinion ,well logs can be used for correlations in the future , locating faults, lithological tops , fluidos, providing affective and very useful information for stopping wells.

There are multiple sources to map under ground structure of earth which includes Seismic survey, Electrical resistivity, Gravity resistivity, GPR, etc

Besides all enumerated tools underground structure exact composition and depth are deciphered with help of seismic tomography.Nuerous works are available by Aucken and Esben.Tgese tool are justifying the temp and comp structure of subsurface of Cirebiundary and Mantke crust interface too.Its shor of depth penetratiin can be adjusted to underground water layer too.TMT sounding and accelorometre deployment besides Magnetometer wave transition also depict inside structure and composition

All of the above geophysical techniques will not give you real observable structural geology. If you combine the output from these systems with my EagleEye system then you do get real structural geology. This is the greatest advantage you can get with any geoscience system. EagleEye can even interrogate underground photos to give structural geology. See my website geotreks.com.au or my LinkedIn posts to see how powerful EagleEye is. Cheers Bob

I have used a spectrum of tools, each one has its limitation. You need to understand the task, define what outcome and accuracy you want then decide the best method of mapping.

O melhor método para identificar infraestruturas soterradas, ou mesmo qualquer uma ou outra fei??o, será o método que melhor descriminar o contraste entre o alvo pretendido e a envolvente. A decis?o e escolha do método deverá depender do conhecimento específico do alvo pretendido (características físicas), do conhecimento geológico das estruturas e unidades geológicas envolventes, das limita??es do método geofísico a escolher, e também importante, a defini??o da geometria de aquisi??o, profundidade de investiga??o, resolu??o horizontal e vertical a dada profundidade, em fun??o das dimens?es do objecto que se quer mapear.

As an enthusiastic scientist I have used the not so well documented methods of electroseismics and magnetotellurics for high profile geotechnical projects. Electroseimics was used for structural mapping, magnetotellurics was used for shafts and tunnels detecting. The results were amazing, but not without good data manipulation techniques and interpretation skills.