Multispectral Imaging

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Exploration Technique: Multispectral Imaging

Exploration Technique Information
Exploration Group: Remote Sensing Techniques
Exploration Sub Group: Passive Sensors
Parent Exploration Technique: Passive Sensors
Information Provided by Technique
Lithology: relative mineral maps
Stratigraphic/Structural: aerial photographs can show structures
Hydrological: delineate locations of surface water features
Thermal: vegetation maps can show plants stressed due to nearby thermal activity
Cost Information
Low-End Estimate (USD): 10.001,000 centUSD
0.01 kUSD
1.0e-5 MUSD
1.0e-8 TUSD
/ sq. mile
Median Estimate (USD): 370.2337,023 centUSD
0.37 kUSD
3.7023e-4 MUSD
3.7023e-7 TUSD
/ sq. mile
High-End Estimate (USD): 1,312.50131,250 centUSD
1.313 kUSD
0.00131 MUSD
1.3125e-6 TUSD
/ sq. mile
Time Required
Low-End Estimate: 1.50 days0.00411 years
36 hours
0.214 weeks
0.0493 months
/ job
Median Estimate: 29.20 days0.0799 years
700.8 hours
4.171 weeks
0.959 months
/ job
High-End Estimate: 135 days0.37 years
3,240 hours
19.286 weeks
4.435 months
/ job
Additional Info
Cost/Time Dependency: Size, Terrain Complexity, Vegetation, Resolution
Multispectral Imaging:
Multispectral surveys image the earth in an average of ten wide bands over a wide spectral range. Multispectral sensors measure the electromagnetic spectrum in discrete, discontinuous bands (unlike the continuous hyperspectral image). Multispectral sensors are capable of relative material delineation. The thermal wavelength range of the multispectral survey senses heat energy from the Earth's surface. It can be used to sense surface temperature, including anomalies associated with active geothermal or volcanic systems. Both multispectral and hyperspectral remote sensing observations are available. This range can also be used to map mineralogy associate with common rock-forming silicates.
Other definitions:Wikipedia Reegle

Multispectral thermal infrared (also referred to as Thermal Infrared Imagery or Thermal Infrared Spectrometry) sensors image in an average of ten, wide bands, and are capable of relative material delineation. Common sources of multispectral data are NASA’s satellite-based LANDSAT and ASTER imagers, both of which produced public-sector multispectral data at low, government-subsidized prices. The ASTER imager utilizes 14 bands that cover portions of the visible (green, yellow, and red), near infrared (NIR), short wavelength infrared (SWIR), and long wavelength infrared (LWIR) ranges of the electromagnetic spectrum (~0.520-11.650 microns) at 15 to 90 m resolution.[1] The current iteration of the LANDSAT satellite (LANDSAT 8) images the electromagnetic spectrum of the earth’s land surface in the visible (blue, green, and red), NIR, SWIR, and LWIR ranges.[2] The infrared portion of the spectrum is measured on 6 of 11 bands, which collectively cover wavelengths from 0.433 - 12.50 microns at 15 to 100 m resolution. Previous generations of the LANDSAT imager collected data in 7-bands covering the visible, NIR, and SWIR portions of the spectrum. Multispectral data can also be collected via fixed wing aircraft at higher resolutions using a Thermal Infrared Multspectral Scanner (TIMS). A typical TIMS system images the LWIR portion of the spectrum within the 8.2-12.2 micron range split across 6 bands.[3]

Processed data from these instruments are used for the characterization of rocks, minerals, soils, vegetation, and surface coatings.[3] Rock types can be differentiated by their free silica, carbonate, clay, and sulfate contents. Multispectral surveys can also provide information about alteration and weathering, as well as an understanding of surface emissivity, porosity, grain size, and roughness. Determinations of water surface and forest canopy temperatures can also be derived from the data. As an example, multispectral images from NASA’s LANDSAT satellite have historically been used to create maps of the surface, delineating clay from iron-oxides.[4]

Use in Geothermal Exploration
Historically, multispectral imaging has been used to create surface maps. Multispectral data have also been used in geothermal exploration to detect and map relative mineral determinations, shallow subsurface thermal anomalies, and abnormalities in vegetation.

Relative Mineral Maps
Although absolute mineral determinations are not possible using multispectral data, mineral types associated with hydrothermal activity can be mapped to show a generalized alteration distribution of features that potential relate to active or fossil geothermal systems. Association of alteration mineral types with identified structures adds confidence to these interpretations. For example, the detection of clay minerals along a fault trace could represent the effects of weathering and/or hydrothermal alteration. In contrast, the detection of pervasive silicification along a similar feature could indicate the presence of an active or fossil hydrothermal system.
Vegetation Maps
Vegetation maps typically only of mildly interest in geothermal exploration, although multispectral images can be used to map the health of local vegetation. In some areas, geothermal activity can cause vegetation stress – in these cases, vegetation maps can be used to define areas affected by hydrothermal activity. This is common along faults acting as conduits in active hydrothermal systems, because heat, changes in groundwater pH, or presence of gasses such as CO2 and H2S can cause plant stress. Substantial CO2 degassing in magmatic environments can cause wholesale vegetation kills, which are also visible using satellite and aerial imaging.

Related Techniques
Multispectral thermal infrared imaging has been eclipsed recently by the advancement of hyperspectral imaging, which offers greater spectral fidelity. For comparative purposes, hyperspectral sensors image the earth in many hundreds of narrow bands (typically over a hundred) in the visible, NIR, and SWIR wavelength range (~0.35 - 2.5 microns). While hyperspectral datasets are large and computationally intensive to process, they are capable of absolute surface material identification (e.g. kaolinite vs. alunite or hematite vs. goethite). Though many in the industry still appreciate LANDSAT and ASTER multispectral images, remote sensing-based maps created from hyperspectral data for use in geothermal exploration are categorically more accurate, more precise and richer in information than multispectral datasets.[4]

Data Access and Acquisition
Multispectral data from NASA’s LANDSAT and ASTER satellites are freely available to the public at no cost.
Best Practices
Relative mineral determinations should always be verified in the field to ensure that distributions determined using multispectral data are accurate. Increasingly, multispectral imaging as a hydrothermal exploration technique has been replaced by Hyperspectral Imaging.
Potential Pitfalls
While multispectral thermal infrared data are capable of providing estimates of relative land surface temperature, there are many variables that must be considered.[5] Atmospheric properties, emissivity, soil moisture, and several other parameters can all affect the accuracy of temperature determinations.

  1. ASTER Homepage
  2. Landsat Data Continuity Mission Brochure
  3. 3.0 3.1 TIMS Instrument Description
  4. 4.0 4.1 Katherine Young,Timothy Reber,Kermit Witherbee. 2012. Hydrothermal Exploration Best Practices and Geothermal Knowledge Exchange on Openei. In: Proceedings of the Thirty-Seventh Workshop on Geothermal Reservoir Engineering. Thirty-Seventh Workshop on Geothermal Reservoir Engineering; 2012/01/30; Stanford, CA. Stanford, CA: Stanford University, Stanford Geothermal Program; p.
  5. TIR (ASTER) Geothermal Anomalies

Page Area Activity Start Date Activity End Date Reference Material
Multispectral Imaging (Jones, Et Al., 2010) Unspecified

Multispectral Imaging (Laney, 2005) Unspecified

Multispectral Imaging (Lewicki & Oldenburg) Unspecified

Multispectral Imaging (Lewicki & Oldenburg, 2004) Unspecified

Multispectral Imaging (Lewicki & Oldenburg, 2005) Unspecified

Multispectral Imaging (Monaster And Coolbaugh, 2007) Unspecified

Multispectral Imaging (Pieri & Abrams, 2004) Unspecified

Multispectral Imaging At Alum Area (DOE GTP) Alum Geothermal Area

Multispectral Imaging At Brady Hot Springs Area (Laney, 2005) Brady Hot Springs Area

Multispectral Imaging At Buffalo Valley Hot Springs Area (Laney, 2005) Buffalo Valley Hot Springs Area

Multispectral Imaging At Buffalo Valley Hot Springs Area (Littlefield & Calvin, 2009) Buffalo Valley Hot Springs Area

Multispectral Imaging At Columbus Salt Marsh Area (Shevenell, Et Al., 2008) Columbus Salt Marsh Area

Multispectral Imaging At Coso Geothermal Area (1990) Coso Geothermal Area 1990 1990

Multispectral Imaging At Cove Fort Area (Laney, 2005) Cove Fort Geothermal Area

Multispectral Imaging At Dixie Meadows Area (Martin, Et Al., 2004) Dixie Meadows Geothermal Area

Multispectral Imaging At Dixie Meadows Area (Pickles, Et Al., 2003) Dixie Meadows Geothermal Area

Multispectral Imaging At Dixie Valley Geothermal Area (Pal & Nash, 2003) Dixie Valley Geothermal Area

Multispectral Imaging At Fish Lake Valley Area (Deymonaz, Et Al., 2008) Fish Lake Valley Area

Multispectral Imaging At Fort Bliss Area (DOE GTP) Fort Bliss Area

Multispectral Imaging At Glass Buttes Area (DOE GTP) Glass Buttes Area

Multispectral Imaging At Long Valley Caldera Geothermal Area (Pickles, Et Al., 2001) Long Valley Caldera Geothermal Area 2001

Multispectral Imaging At Maui Area (DOE GTP) Maui Area

Multispectral Imaging At Pilgrim Hot Springs Area (Prakash, Et Al., 2010) Pilgrim Hot Springs Area

Multispectral Imaging At Rangely Oilfield Area (Pickles & Cover, 2004) Rangely Oilfield Geothermal Area

Multispectral Imaging At Rhodes Marsh Area (Kratt, Et Al., 2006) Rhodes Marsh Area

Multispectral Imaging At Rhodes Marsh Area (Shevenell, Et Al., 2008) Rhodes Marsh Area

Multispectral Imaging At Salton Sea Area (Reath, Et Al., 2010) Salton Sea Area

Multispectral Imaging At Silver Peak Area (DOE GTP) Silver Peak Area

Multispectral Imaging At Silver Peak Area (Laney, 2005) Silver Peak Area

Multispectral Imaging At Teels Marsh Area (Kratt, Et Al., 2006) Teels Marsh Area

Multispectral Imaging At Teels Marsh Area (Shevenell, Et Al., 2008) Teels Marsh Area

Multispectral Imaging At The Needles Area (Kratt, Et Al., 2005) The Needles Area

Multispectral Imaging At The Needles Area (Laney, 2005) The Needles Area

Multispectral Imaging At Yellowstone Region (Hellman & Ramsey, 2004) Yellowstone Caldera Geothermal Region

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