I do not think locating geothermal potential regions is an uni-variant decision. There are three main layers which should be used in order to detect these sites with low uncertainty. The first one is geothermal indicator minerals such as sinter. The presence of sinter is of particular relevance in geothermal exploration. Now in order to address this issue, there are thousands of approaches for classification using Hyperspectral data (from spectral analysis to artificial intelligence classifiers). The second layer is land surface temperature. It is typical to use ASTER data which has really high resolution and useful bands in order to estimate emissivity. You should mitigate atmospheric and topographic effects too. The thermal insertia is another influential factor to consider that thermal images should be available at the times of maximum and minimum temperatures on the same data in order to minimize this effect. Regional tectonic and geology is the last layer.

Since, my thesis might have become exactly this topic, I researched on many papers and the summary was what I mentioned above.

The most appropriate place for studying this topic is definitely University of Nevada:

Great Basin Center for Geothermal Energy and the Arthur Brant Laboratory for Exploration Geophysics, University of Nevada, Reno, 89557 USA. (Nevada has the second largest geothermal potential in U.S)

I do not think locating geothermal potential regions is an uni-variant decision. There are three main layers which should be used in order to detect these sites with low uncertainty. The first one is geothermal indicator minerals such as sinter. The presence of sinter is of particular relevance in geothermal exploration. Now in order to address this issue, there are thousands of approaches for classification using Hyperspectral data (from spectral analysis to artificial intelligence classifiers). The second layer is land surface temperature. It is typical to use ASTER data which has really high resolution and useful bands in order to estimate emissivity. You should mitigate atmospheric and topographic effects too. The thermal insertia is another influential factor to consider that thermal images should be available at the times of maximum and minimum temperatures on the same data in order to minimize this effect. Regional tectonic and geology is the last layer.

Since, my thesis might have become exactly this topic, I researched on many papers and the summary was what I mentioned above.

The most appropriate place for studying this topic is definitely University of Nevada:

Great Basin Center for Geothermal Energy and the Arthur Brant Laboratory for Exploration Geophysics, University of Nevada, Reno, 89557 USA. (Nevada has the second largest geothermal potential in U.S)

To my knowledge, there are two methods in general using the background ratiations. Passive techniques such as IR imaging based on hyper-sensitive etchellon spectrometry to measure TIR. Another approach is based on active techniques.The investigation on the underground effluents into atmospheres using DIAL and LIBS-Raman lidars. There are several articles available may be helpful to review recent developments:

* P.Parvin et al, "Novel Techniques for Safer Operation of Present Nuclear Power Plants After Fukushima Disaster", Recent Patents in Mechanical Engineering , 6,1,58-74 (2013).

* P.Parvin and GH. Shayeganrad, "DIAL–phoswich hybrid system for remote sensing of radioactive plumes in order to evaluate external dose rate ", Progress in Nuclear Energy, 51(2013),320-287.

* Hasan Kariminezhad, Parviz Parvin, Fazel Borna, Ali Bavali ," SF6 Leak Derection Using TEA-CO2 DIAL for High Voltage Installations " ,Optics and Lasers in Engineering , 48(4):491 -499 (2010)..

Why don`t you consider Geophysics, specially EM methods.

Well, I would say this is just getting started. In geothermal remote sensing the most important point is anomalies. I still have issues with its accuracy, but it definitely gives general idea about potentials at early stages of the exploration, and useful for decision makers to keep hopes high, interesting practical developments have been made in Kyushu University and NZ, plz let me know if you need more info. I will try to find links. Good Luck

Satellite, Winter, Infra-red photography

salem M salem

Aster data is one of the effective methods for geothermal exploration especially the hydrothermally mineral bearing alteration zones.

Geophysical surveys can add value to the geothermal exploration processes. Magnetic data can provide estimation of the depth to the bottom of the magnetic crust (Curie isotherm), Potential field data can provide mapping of the structures which is one of the important factor in the geothermal field. On the other hand, EM and resistivity surveys can provide valuable information concerning the groundwater potentiality and flow at the geothermal field.

The method of application of remote sensing data is reduced to two stages:

1. Structural interpretation of any satellite data (Landsat, IRS, Spot? World View2, Rapid Eye, etc.) Selection depends on the scope of research and the required spatial resolution space images. Allocated fractured (lineament) zones and their intersection nodes as possible migration path thermal waters to the surface.

2. Analysis of thermal fields, which were obtained by processing data from satellites with thermal sensors (NOAA, TERRA (MODIS, ASTER), Landsat). Spatial resolution NOAA, TERRA (MODIS) in TIR range 1km, ASTER 90 m, Landsat original: L4-5 120 m, L7 60m, L8 100 m. USGS (http://earthexplorer.usgs.gov/) is restated Landsat 30 meters per pixel. The choice is yours.

An analysis of thermal fields identify thermal anomalies that correlate with the results of the structural decoding. Further, forecasted land allocated for searches hydrotherms

Additionally, depending on the geological conditions of the area, the reflectance spectra are analyzed multispectral satellite data for the search of hydrothermally altered rocks using spectral libraries. (Best ASTER)

All processing of spatial data necessarily involves the atmospheric correction and consideration of the effect of vegetation (NDVI vegetation indices are used, and the like).

This is only the first stage of searching, then the complex includes geophysical methods and drilling

Dear all,

Thanks for your contribution! There are some really great suggestions

The best success in my experience has been applying structural interpretation and using known alteration areas to train classification routines and then field checking. The work we have done with the thermal bands even at night has not been effective except where the areas are so hot that they correspond to known fumaroles, large hot pools, or crater activity. The solar impact on the ground temperature is often strong enough to bury other anomalies in noise associated with vegetation, shallow or surface water, and slope aspect. Measuring temperature a couple of meters down using probes is better but can still have problematic noise. I have also only had limited success using band ratios or mineral ID. This is probably due to the relatively limited exposure of alteration associated with an active system compared to better success shown in mineral exploration where the mineralization is much better exposed. We once tested a comparison between advanced ASTER principal components and mineral ID processing with field spectral calibration in northern Chile and found that it was only as good as using air photos and then field checking.

In geothermal exploration and reservoir characterization, one of the objective is to map overlying clay cap. Clay cap is much more conductive than geothermal reservoir and therefore electromagnetic (EM) methods (e.g., magnetotellurics methods) can be used. There are several publications on this.

The variety of responses seem to reflect:

1. different definitions of remote sensing, with most assuming that it means remote imaging from satellites or aircraft but some including any method that does not physically penetrate the surface, such as the MT resistivity imaging mentioned by Kumar and others;

2. different experiences with satellite imaging by those who do research on the subject and those who have followed up with exploration drilling, which has generally disappointed the hopes of those hoping for direct correlation with thermal IR or indirect correlation through mineral identification, as outlined by Glenn Melosh.

Although I routinely apply the MT resistivity method in geothermal exploration, I suspect the initial query was directed at remote imaging.

An aspect of remote sensing (i.e. imaging) often glossed by researchers is that resolution in terms of pixel size has often produced greater practical benefit than improved spectral resolution.

Examples

Almost every geothermal geoscience project benefits from having 50 cm images like the 4 band images from Worldview2 or GeoEye overlaid on a 30 m digital elevation model, whereas the practical success of the nominally more capable 15 m SWIR imaging from ASTER may be limited until higher resolution systems provide better separation of vegetation and mineral signals.

Although I generally agree with Glenn Melosh's points with respect to detecting diffuse heat loss from geothermal reservoirs using currently available satellite imaging, there remains hope that relatively low cost aircraft TIR systems resolving pixel sizes of a few 10s of cm (much better than the many 10s of m available for satellite TIR) might detect previously undiscovered zones of focused heat loss that unambiguously exceed the background variation associated with vegetation, aspect and so on. The FLIR system flown by UA-Fairbanks at Pilgrim Hot Springs was arguably a success, albeit imaging an easy target, hot springs among permafrost.

There is a good example of the value of high spatial resolution thermal images in a fumarole area in the attached paper (Figure 7) as William Cumming suggested. Although the location of the thermal area was already well known (as are most high temperature features), the detailed image of thermal emission provided useful information on possible permeability patterns The lack of vegetation and other surface moisture in this area allows a noise free image in this case.