On September 26, 2019, an Mw 6.5 earthquake occurred 23 km northeast of Ambon City, Indonesia, fo... more On September 26, 2019, an Mw 6.5 earthquake occurred 23 km northeast of Ambon City, Indonesia, followed by numerous aftershock series related to a complex fault network reactivation in the Ambon and Seram region. Using moment tensor inversion, we identify the kinematics of fault reactivation based on the focal mechanism solution of 20 aftershocks with Mw > 3.2 and analyze the earthquake sequence from both focal mechanism solutions and spatiotemporal seismicity. The MTs solution of aftershocks revealed three different characteristics of fault reactivation: (i) a 35 km long N-S oriented main fault characterized by dextral strike-slip (ii) a NE-SW reverse fault segment with a ~ 55° northeastward dip located in southwest Seram, and (iii) two strike-slip segments (NNW-SSE and NNE-SSW trends) and an E-W normal fault in Ambon Island. Analysis of spatiotemporal seismicity with the MTs solution suggests that the Mw 6.5 Ambon aftershock sequences can be described as follows: (i) an Mw 6.5 ...
IOP Conference Series: Earth and Environmental Science, 2021
The island of Ambon lies on complex tectonics, part of Banda Arc which is driven by the Australia... more The island of Ambon lies on complex tectonics, part of Banda Arc which is driven by the Australia – Eurasia collision. Historical earthquake data show that an earthquake resulting the greatest tsunami in Indonesia had occurred at Ambon Island. On 26 September 2019, Ambon was shaken by an M 6.5 earthquake at a depth of 10 km (BMKG). In this study, we use ambient noise data from 11 temporary stations deployed by ITB and 4 permanent stations owned BMKG which are recorded from October until December 2019. Here, we purely use the vertical component of seismogram to retrieve the Empirical Green’s Function of Rayleigh waves. Cross-correlations were obtained from the daily data series and stacked the day-by-day cross-correlation data into one inter-station cross-correlation. The Empirical Green’s Function is seen at the band period 1-15 s. As a part of our study, we analyze the Green’s Function with frequency-time analysis (FTAN) to get Rayleigh wave group velocity. The group velocity of Ra...
On September 26, 2019, a significant, Mw 6.5, earthquake shook Ambon region, Indonesia, causing s... more On September 26, 2019, a significant, Mw 6.5, earthquake shook Ambon region, Indonesia, causing severe damage on the Island(s) of Ambon. Due to the complexity of the fault network and in-situ stress field it was, up to now, not possible to define the fault plane using data from the BMKG regional seismic network. In this study, we analyze the fault plane of the 2019 Ambon earthquake and the reactivation potential of the surrounding faults using local networks. Eleven stations were deployed to monitor the aftershocks from October 18 th to December 15 th , 2019 augmented with data of four regional stations. During the monitoring period, 1,778 events were identified comprised of 10,938 P-and 10,315 and S-wave arrival times. The locations of aftershock were determined in a stepwise approach, i.e. (i) initial location determination using a non-linear approach, (ii) updating the velocity model, and (iii) relative double-difference relocation. Slip inversion using teleseismic data was performed to infer of high strain relief of the mainshock and to compute its associated static stress transfer (ΔCFF). Based on aftershock distribution and finite fault modeling, we conclude that the Mw 6.5 Ambon earthquake occurred on a N-S oriented fault plane. Two clusters consisting of~60% of total events are located at both tips of the plane. Another cluster~30% was sharply aligned in a NE-SW trend, 10 km westward, starting by an Mw 5.2 event on November 2 nd , 2019. The b-value of the NE-SW events is~0.25 lower than the other clusters with a b-value of 0.85±0.14. ΔCFF imparted by the mainshock caused~0.5 Bar stress increase on the NE-SW fault. We concluded that the NE-SW trend was the reactivation of a preexisting fault crossing Ambon Island. The triggered large aftershock caused further significant damages to already weakened infrastructure and, thus, had the largest mapped damage area.
The purpose of this study was to use a combination of high spatial resolution airborne visible, n... more The purpose of this study was to use a combination of high spatial resolution airborne visible, near infrared, short wave infrared (VNIR/SWIR) and thermal infrared (TIR) image data to remotely identify and map exposed alteration minerals around both active and ancient hydrothermal systems, and the mineral by-products of weathered mine tailings. Three case study areas were evaluated: (1) Steamboat Springs, as an active geothermal system; (2) Geiger Grade and Virginia City, as ancient hydrothermal systems; and (3) Virginia City, as a historic mining district. Remote sensing data from the Airborne Visible Infrared Imaging Spectrometer (AVIRIS), as well as data from newly developed airborne imaging spectrometers: SpecTIR Corporation's airborne hyperspectral imager (HyperSpecTIR), the MODIS-ASTER airborne simulator (MASTER), and the Spatially Enhanced Broadband Array Spectrograph System (SEBASS) were acquired and processed into mineral maps based on the unique spectral signatures of image pixels. VNIR/SWIR and TIR field spectrometer data were collected for both calibration and validation of the remote data sets, and field sampling, laboratory spectral analyses and XRD analyses were made to corroborate the surface mineralogy identified by spectroscopic methods. In all of the case study areas the minerals mapped included sinter, quartz/chalcedony, albite, calcite, dolomite, hydrous sulfate minerals (tamarugite, alunogen, gypsum and hexahydrite), jarosite, hematite, goethite, alunite, pyrophyllite, kaolinite, montmorillonite/muscovite, and chlorite. The results were synthesized into single thematic mineral maps and indicate that the combination of multi-channel infrared remote sensing data is an effective technique for the unique identification and mapping of weathering and alteration minerals that are characteristic of active and fossil hydrothermal systems, as well as acid mine drainage potential. This study provides many examples of the advantages of high spatial and high spectral resolution measurements, and the utility of combining image data from multiple wavelength regions, and should be helpful in placing some limits on, and setting some goals for, the specifications of future airborne and space borne remote sensing systems for geological applications. The next advance in geologic remote sensing technology should combine the advantages of high spatial resolution, wide swath, high spectral resolution and high signal-to-noise ratio with measurements in both VNIR/SWIR and TIR spectral regions.
Fluid flow along normal faults has created much of the geothermal energy that is currently being ... more Fluid flow along normal faults has created much of the geothermal energy that is currently being exploited in the Basin & Range. We used remote sensing (HyMap, ASTER) data and field-based methods in the Humboldt Block of the northwest Basin & Range to map fault zones and the surface distribution of minerals associated with hydrothermal fluid flow. The Humboldt Block lies on the Battle Mountain High heat flow area (>100 m/V/m2), and has very high shallow water temperatures of around 200° F. This area has undergone large amounts of extension from Oligocene to the present, accommodated along large, range-bounding normal faults. The western flank of the Humboldt Range is bounded by a normal fault that trends N-NE, dips W, and brings into contact Mesozoic sedimentary and volcanic rocks with Quaternary deposits. The structural setting, high heat flow, and high shallow water temperatures suggest significant geothermal potential for the Humboldt Block. We carried out the remote sensing study in two stages. We created fault maps by overlaying ASTER data onto a DEM, and mapping lithologic changes and structurally controlled lineations that were distinct from expected topographic patterns. This revealed two distinct fault patterns: N-NE trending faults and NW-SE trending faults. We then used HyMap (hyperspectral) data to identify and map minerals associated with hydrothermal fluid flow and their relation to regional structure. Sinter was mapped in the Humboldt River Valley along two distinct N-NE trends. Kaolinite was mapped in the Humboldt Range along the range front fault, and NW-SE trends.
... in the Mid Chesapeake Bay Through Integration of Observations and Radiative Transfer Closure ... more ... in the Mid Chesapeake Bay Through Integration of Observations and Radiative Transfer Closure Maria Tzortziou, Charles L. Gallegos, Patrick J. Neale, Ajit Subramaniam, Jay R. Herman and Lawrence W. Harding, Jr. ... 1995, Harding et al. 2004, Gallegos and Bergstrom 2005). ...
In many environments, vegetation is known to reflect the mineralogy of the soils in which it grow... more In many environments, vegetation is known to reflect the mineralogy of the soils in which it grows. Similarly, regolith landforms, which are a function of underlying geology and localized geomorphological processes, affect vegetation community composition and structure. Eleven primary regolith landform units were mapped during fieldwork in the Goldfields region of Western Australia, and the overlying vegetation units were characterised in detail. The presence and abundance of gold in the landscape is closely associated with particular regolith landform units. Results revealed quantifiable differences in species composition and diversity, vegetative cover, vegetation frequency and observable differences in soils and leaf litter accumulation for each of the regolith units. Spectral analysis of all vegetation components was also undertaken using a laboratory spectrometer. Landsat TM and ASTER imagery were used to assess how well the various regolith landform units could be mapped through remote sensing of the vegetation. Very high classification accuracies of approximately 90% were achieved in mapping regolith units through the remotely sensed imagery used in the study. Despite high levels of vegetative cover over most units, spectral unmixing of scene components proved to be non-viable. Remote sensing of vegetation as a mapping surrogate for regolith materials in the Goldfields shows significant promise, as well as being environmentally benign and a far less costly and laborious means of determining where to direct gold exploration efforts.
The Multiple Instrument Distributed Aperture Sensor (MIDAS) is a diffraction-limited, wide-field ... more The Multiple Instrument Distributed Aperture Sensor (MIDAS) is a diffraction-limited, wide-field imaging spectrometer that utilizes distributed apertures and optical interferometer techniques to achieve simultaneous high spatial and spectral resolution. Here we describe the results of a science and technical feasibility study of MIDAS prototypes funded under the NASA High Capability Instrument Concepts and Technology (HCICT) program as a potential science payload for missions to the outer planets and their icy satellites. The high spatial resolution capabilities of MIDAS combined with nm spectral resolution will greatly advance our understanding of icy satellite surface composition in terms of minerals, organics, volatiles, and their mixtures. From 100 km mapping orbits, cm-scale imagery from MIDAS could revolutionize our understanding of the geology, dynamics, and history of icy moon surfaces. From higher orbits, MIDAS can engage in global, high resolution imaging spectroscopy with m-scale resolution for months at a time. Beyond traditional remote sensing, MIDAS is well suited to active techniques, including remote Raman, Fluorescence, and IR illumination investigations, in order to resolve surface composition and explore otherwise dim regions.
This paper discusses the applicability and results of simple remote sensing work conducted for ex... more This paper discusses the applicability and results of simple remote sensing work conducted for exploration for minerals in Nepal. The method of lineament intersection and its density value was used to delineate areas for detailed study as possible sites of mineralization. Lineaments from Landsat imagery, using color composite and black and white prints of different bands, were plotted on a map scale 1:500 000. The map was carefully compared with toposheet and other available geological maps and operational navigation charts to avoid any linear features that were not of geological origin. Lineaments were counted, measured and plotted in octants according to their direction, and a fracture density map of the country was prepared. on the basis of lineament intersection and density value, a map showing ``prospective sites'' for metal mineralization in Nepal was prepared. These possible sites were later compared with existing maps of geological, geophysical and geochemical anomalies. The result was encouraging because a considerable number of sites deduced by this remote sensing technique showed close resemblance with other anomalies identified by conventional methods. Taking into consideration the terrain and its difficult accessibility--requiring money and time to find anomalies for detailed study by any conventional method--it was decided that a second stage detailed study of some selected sites will be carried out based on remote sensing data. It is too early, however, to evaluate the real benefit of remote sensing techniques for mineral exploration in Nepal. It was found to be helpful in the sense that it provided the potential areas for detailed study and the answer to the questions ``where to look'' and ``how to look''--vital questions in any mineral exploration program of a developing country.
Remotely sensed mineralogy will likely play a large role in the selection of future Mars landed s... more Remotely sensed mineralogy will likely play a large role in the selection of future Mars landed science locations, and with the success of the OMEGA experiment on Mars Express (identification of sulfate, phyllosilicate minerals), the data from CRISM on MRO will also be important. One of the crucial challenges in this activity is how to identify promising targets from spatially coarse data for in situ investigation. We present an approach for systematic integration of data from remote sensing to rover scales. We incorporate data from the sample, to in situ, to regional remotely sensed data. We test the applicability of this approach to Mars using VNIR field- and remotely sensed spectra from Rio Tinto, Spain. The Rio Tinto has a diverse iron oxide and hydrous sulfate mineralogy in a very acidic environment and is considered a mineralogic and biologic analog for Mars, especially Terra Meridiani. We use remotely sensed Hymap data (8 m per pixel) to predict small areas with high mineral diversity, and then verify the identified locales through field work at the sample and in situ scales. We apply the Spectral Variance Index (SVI), a method which blends spatial and spectral components, to locate regions with increased mineral diversity. Remotely acquired data from the Hymap spectrometer (8 m per pixel) are binned into 25x25 pixel (or 200m x 200m) cells. We compute their mean and variance by wavelength and their expected spectral variance due to their albedo. Cells with a spectral variance significantly higher than their expected variance have more spectra variability than average, and thus are likely to have more mineralogic diversity. While this technique identifies areas of mineral diversity, it is less able to identify unique mineralogy. To catalog the mineralogy present at the Rio Tinto, we perform a Minimum Noise Function (MNF) followed by a Pixel Purity Index (PPI) function on the Hymap data. Pixels that are flagged by this process are unique in the scene and tend to represent pure mineralogy. Minerals thus identified include goethite, hematite, gypsum, hydrated Fe3+ sulfates including copiapite, hydrated Fe2+ sulfates including rozenite and melanterite, and various clay minerals. The SVI approach identifies areas of high mineralogic diversity in the Rio Tinto, and could also be applied to Mars orbital spectral datasets, such as OMEGA and CRISM. This exploration strategy for iron oxide and sulfate-rich environments over a range of spatial scales could allow us to pinpoint Rio Tinto-like deposits on Mars, a useful ability in the search for future landing sites of mineralogic and astrobiologic interest.
Remote sensing, the science of evaluating the earth and its systems from a distance, continues to... more Remote sensing, the science of evaluating the earth and its systems from a distance, continues to become more exact in its methods and more widely used and accepted as a tool for geological investigations. Nonetheless, methods of processing and analyzing remotely sensed data ...
The aim of the present study is to define the most suitable methodologies for ASTER data pre-proc... more The aim of the present study is to define the most suitable methodologies for ASTER data pre-processing and analysis in order to enhance peraluminous granitoid rocks in rugged and vegetated areas.The research started with raw image data pre-processing and continued with a comparison of satellite, field and laboratory data. The masking technique adopted to isolate rocky pixels was of fundamental importance to perform further analysis. An integration of density-sliced images and false colour composite images of Band Ratio, Relative Absorption Band Depth and Principal Component Analysis allowed us to generate a geological map that highlights a new granitoid body (Buraburi Granite) and the surrounding host rocks in the Dolpo region (western Nepal). The Buraburi Granite was mapped and sampled integrating remotely sensed ASTER data with analysis of rocks and minerals spectral signatures.The innovative approach that we have adopted considers the absorption features of particular lichen species (acidophilic). The results highlight the importance of considering acidophilic lichen means of detecting granitoid rocks. Furthermore, since peraluminous granitoids (i.e. Buraburi granite) have a considerable Al2O3 bulk rock content, the Muscovite Al–OH absorption peaks centred in the 6th ASTER band were also considered an important parameter for their detection.Field observations confirm the results of remote sensing analysis showing the intrusive relationship between the newly discovered 110 km2 granitoid body and the wall rocks of the Higher Himalayan Crystalline and the Tibetan Sedimentary Sequence.In conclusion, the proposed methods have great potential for granitoid mapping in vegetated and rough terrains, particularly those with climatic and geological conditions similar to the ones of the Southern Himalayan belt.► ASTER data has been successfully used in extreme terrain (rugged and vegetated). ► Rocky pixel extraction is fundamental for remote lithological discrimination. ► Acidophilic lichens spectra are a proxy for the remote detection of granitoid rocks. ► A previously unknown large granitoid body has been discovered.
The area under study covers an area of 640 km 2 , located in the southern part of Iranian Volcani... more The area under study covers an area of 640 km 2 , located in the southern part of Iranian Volcanic-Sedimentary Belt. ETM+ images have been used for alteration mapping. Satellit images can be used for enhancing the areas with hydroxyl and iron oxide minerals. However field checking has shown that this method is not able to enhance all the areas with hydrothermal alteration. At the same time many of the altered areas do not have good signature in the geophysical data. In order to recognize such areas integration of remote sensing and geophysical data can be helpful. The Darrehzar Cu deposit is chosen as a control area. The data analysis and integration of geophysical and remote sensing data is performed by using directed principal components. This technique is found to be useful for the delineation of hydrothermaly altered areas with more confidence.
Satellite remote sensing images can be interpreted to provide important information of large-scal... more Satellite remote sensing images can be interpreted to provide important information of large-scale natural resources, such as lands, oceans, mountains, rivers, forests and minerals for Earth observations. Recent advances of remote sensing technologies have improved the availability of satellite imagery in a wide range of applications including high dimensional remote sensing data sets (e.g. high spectral and high spatial resolution images). The information of high dimensional remote sensing images obtained by state-of-the-art sensor technologies can be identified more accurately than images acquired by conventional remote sensing techniques. However, due to its large volume of image data, it requires a huge amount of storages and computing time. In response, the computational complexity of data processing for high dimensional remote sensing data analysis will increase. Consequently, this paper proposes a novel classification algorithm based on semi-matroid structure, known as the parallel k-dimensional tree semi-matroid (PKTSM) classification, which adopts a new hybrid parallel approach to deal with high dimensional data sets. It is implemented by combining the message passing interface (MPI) library, the open multi-processing (OpenMP) application programming interface and the compute unified device architecture (CUDA) of graphics processing units (GPU) in a hybrid mode. The effectiveness of the proposed PKTSM is evaluated by using MODIS/ASTER airborne simulator (MASTER) images and airborne synthetic aperture radar (AIRSAR) images for land cover classification during the Pacrim II campaign. The experimental results demonstrated that the proposed hybrid PKTSM can significantly improve the performance in terms of both computational speed-up and classification accuracy.
On September 26, 2019, an Mw 6.5 earthquake occurred 23 km northeast of Ambon City, Indonesia, fo... more On September 26, 2019, an Mw 6.5 earthquake occurred 23 km northeast of Ambon City, Indonesia, followed by numerous aftershock series related to a complex fault network reactivation in the Ambon and Seram region. Using moment tensor inversion, we identify the kinematics of fault reactivation based on the focal mechanism solution of 20 aftershocks with Mw > 3.2 and analyze the earthquake sequence from both focal mechanism solutions and spatiotemporal seismicity. The MTs solution of aftershocks revealed three different characteristics of fault reactivation: (i) a 35 km long N-S oriented main fault characterized by dextral strike-slip (ii) a NE-SW reverse fault segment with a ~ 55° northeastward dip located in southwest Seram, and (iii) two strike-slip segments (NNW-SSE and NNE-SSW trends) and an E-W normal fault in Ambon Island. Analysis of spatiotemporal seismicity with the MTs solution suggests that the Mw 6.5 Ambon aftershock sequences can be described as follows: (i) an Mw 6.5 ...
IOP Conference Series: Earth and Environmental Science, 2021
The island of Ambon lies on complex tectonics, part of Banda Arc which is driven by the Australia... more The island of Ambon lies on complex tectonics, part of Banda Arc which is driven by the Australia – Eurasia collision. Historical earthquake data show that an earthquake resulting the greatest tsunami in Indonesia had occurred at Ambon Island. On 26 September 2019, Ambon was shaken by an M 6.5 earthquake at a depth of 10 km (BMKG). In this study, we use ambient noise data from 11 temporary stations deployed by ITB and 4 permanent stations owned BMKG which are recorded from October until December 2019. Here, we purely use the vertical component of seismogram to retrieve the Empirical Green’s Function of Rayleigh waves. Cross-correlations were obtained from the daily data series and stacked the day-by-day cross-correlation data into one inter-station cross-correlation. The Empirical Green’s Function is seen at the band period 1-15 s. As a part of our study, we analyze the Green’s Function with frequency-time analysis (FTAN) to get Rayleigh wave group velocity. The group velocity of Ra...
On September 26, 2019, a significant, Mw 6.5, earthquake shook Ambon region, Indonesia, causing s... more On September 26, 2019, a significant, Mw 6.5, earthquake shook Ambon region, Indonesia, causing severe damage on the Island(s) of Ambon. Due to the complexity of the fault network and in-situ stress field it was, up to now, not possible to define the fault plane using data from the BMKG regional seismic network. In this study, we analyze the fault plane of the 2019 Ambon earthquake and the reactivation potential of the surrounding faults using local networks. Eleven stations were deployed to monitor the aftershocks from October 18 th to December 15 th , 2019 augmented with data of four regional stations. During the monitoring period, 1,778 events were identified comprised of 10,938 P-and 10,315 and S-wave arrival times. The locations of aftershock were determined in a stepwise approach, i.e. (i) initial location determination using a non-linear approach, (ii) updating the velocity model, and (iii) relative double-difference relocation. Slip inversion using teleseismic data was performed to infer of high strain relief of the mainshock and to compute its associated static stress transfer (ΔCFF). Based on aftershock distribution and finite fault modeling, we conclude that the Mw 6.5 Ambon earthquake occurred on a N-S oriented fault plane. Two clusters consisting of~60% of total events are located at both tips of the plane. Another cluster~30% was sharply aligned in a NE-SW trend, 10 km westward, starting by an Mw 5.2 event on November 2 nd , 2019. The b-value of the NE-SW events is~0.25 lower than the other clusters with a b-value of 0.85±0.14. ΔCFF imparted by the mainshock caused~0.5 Bar stress increase on the NE-SW fault. We concluded that the NE-SW trend was the reactivation of a preexisting fault crossing Ambon Island. The triggered large aftershock caused further significant damages to already weakened infrastructure and, thus, had the largest mapped damage area.
The purpose of this study was to use a combination of high spatial resolution airborne visible, n... more The purpose of this study was to use a combination of high spatial resolution airborne visible, near infrared, short wave infrared (VNIR/SWIR) and thermal infrared (TIR) image data to remotely identify and map exposed alteration minerals around both active and ancient hydrothermal systems, and the mineral by-products of weathered mine tailings. Three case study areas were evaluated: (1) Steamboat Springs, as an active geothermal system; (2) Geiger Grade and Virginia City, as ancient hydrothermal systems; and (3) Virginia City, as a historic mining district. Remote sensing data from the Airborne Visible Infrared Imaging Spectrometer (AVIRIS), as well as data from newly developed airborne imaging spectrometers: SpecTIR Corporation's airborne hyperspectral imager (HyperSpecTIR), the MODIS-ASTER airborne simulator (MASTER), and the Spatially Enhanced Broadband Array Spectrograph System (SEBASS) were acquired and processed into mineral maps based on the unique spectral signatures of image pixels. VNIR/SWIR and TIR field spectrometer data were collected for both calibration and validation of the remote data sets, and field sampling, laboratory spectral analyses and XRD analyses were made to corroborate the surface mineralogy identified by spectroscopic methods. In all of the case study areas the minerals mapped included sinter, quartz/chalcedony, albite, calcite, dolomite, hydrous sulfate minerals (tamarugite, alunogen, gypsum and hexahydrite), jarosite, hematite, goethite, alunite, pyrophyllite, kaolinite, montmorillonite/muscovite, and chlorite. The results were synthesized into single thematic mineral maps and indicate that the combination of multi-channel infrared remote sensing data is an effective technique for the unique identification and mapping of weathering and alteration minerals that are characteristic of active and fossil hydrothermal systems, as well as acid mine drainage potential. This study provides many examples of the advantages of high spatial and high spectral resolution measurements, and the utility of combining image data from multiple wavelength regions, and should be helpful in placing some limits on, and setting some goals for, the specifications of future airborne and space borne remote sensing systems for geological applications. The next advance in geologic remote sensing technology should combine the advantages of high spatial resolution, wide swath, high spectral resolution and high signal-to-noise ratio with measurements in both VNIR/SWIR and TIR spectral regions.
Fluid flow along normal faults has created much of the geothermal energy that is currently being ... more Fluid flow along normal faults has created much of the geothermal energy that is currently being exploited in the Basin & Range. We used remote sensing (HyMap, ASTER) data and field-based methods in the Humboldt Block of the northwest Basin & Range to map fault zones and the surface distribution of minerals associated with hydrothermal fluid flow. The Humboldt Block lies on the Battle Mountain High heat flow area (>100 m/V/m2), and has very high shallow water temperatures of around 200° F. This area has undergone large amounts of extension from Oligocene to the present, accommodated along large, range-bounding normal faults. The western flank of the Humboldt Range is bounded by a normal fault that trends N-NE, dips W, and brings into contact Mesozoic sedimentary and volcanic rocks with Quaternary deposits. The structural setting, high heat flow, and high shallow water temperatures suggest significant geothermal potential for the Humboldt Block. We carried out the remote sensing study in two stages. We created fault maps by overlaying ASTER data onto a DEM, and mapping lithologic changes and structurally controlled lineations that were distinct from expected topographic patterns. This revealed two distinct fault patterns: N-NE trending faults and NW-SE trending faults. We then used HyMap (hyperspectral) data to identify and map minerals associated with hydrothermal fluid flow and their relation to regional structure. Sinter was mapped in the Humboldt River Valley along two distinct N-NE trends. Kaolinite was mapped in the Humboldt Range along the range front fault, and NW-SE trends.
... in the Mid Chesapeake Bay Through Integration of Observations and Radiative Transfer Closure ... more ... in the Mid Chesapeake Bay Through Integration of Observations and Radiative Transfer Closure Maria Tzortziou, Charles L. Gallegos, Patrick J. Neale, Ajit Subramaniam, Jay R. Herman and Lawrence W. Harding, Jr. ... 1995, Harding et al. 2004, Gallegos and Bergstrom 2005). ...
In many environments, vegetation is known to reflect the mineralogy of the soils in which it grow... more In many environments, vegetation is known to reflect the mineralogy of the soils in which it grows. Similarly, regolith landforms, which are a function of underlying geology and localized geomorphological processes, affect vegetation community composition and structure. Eleven primary regolith landform units were mapped during fieldwork in the Goldfields region of Western Australia, and the overlying vegetation units were characterised in detail. The presence and abundance of gold in the landscape is closely associated with particular regolith landform units. Results revealed quantifiable differences in species composition and diversity, vegetative cover, vegetation frequency and observable differences in soils and leaf litter accumulation for each of the regolith units. Spectral analysis of all vegetation components was also undertaken using a laboratory spectrometer. Landsat TM and ASTER imagery were used to assess how well the various regolith landform units could be mapped through remote sensing of the vegetation. Very high classification accuracies of approximately 90% were achieved in mapping regolith units through the remotely sensed imagery used in the study. Despite high levels of vegetative cover over most units, spectral unmixing of scene components proved to be non-viable. Remote sensing of vegetation as a mapping surrogate for regolith materials in the Goldfields shows significant promise, as well as being environmentally benign and a far less costly and laborious means of determining where to direct gold exploration efforts.
The Multiple Instrument Distributed Aperture Sensor (MIDAS) is a diffraction-limited, wide-field ... more The Multiple Instrument Distributed Aperture Sensor (MIDAS) is a diffraction-limited, wide-field imaging spectrometer that utilizes distributed apertures and optical interferometer techniques to achieve simultaneous high spatial and spectral resolution. Here we describe the results of a science and technical feasibility study of MIDAS prototypes funded under the NASA High Capability Instrument Concepts and Technology (HCICT) program as a potential science payload for missions to the outer planets and their icy satellites. The high spatial resolution capabilities of MIDAS combined with nm spectral resolution will greatly advance our understanding of icy satellite surface composition in terms of minerals, organics, volatiles, and their mixtures. From 100 km mapping orbits, cm-scale imagery from MIDAS could revolutionize our understanding of the geology, dynamics, and history of icy moon surfaces. From higher orbits, MIDAS can engage in global, high resolution imaging spectroscopy with m-scale resolution for months at a time. Beyond traditional remote sensing, MIDAS is well suited to active techniques, including remote Raman, Fluorescence, and IR illumination investigations, in order to resolve surface composition and explore otherwise dim regions.
This paper discusses the applicability and results of simple remote sensing work conducted for ex... more This paper discusses the applicability and results of simple remote sensing work conducted for exploration for minerals in Nepal. The method of lineament intersection and its density value was used to delineate areas for detailed study as possible sites of mineralization. Lineaments from Landsat imagery, using color composite and black and white prints of different bands, were plotted on a map scale 1:500 000. The map was carefully compared with toposheet and other available geological maps and operational navigation charts to avoid any linear features that were not of geological origin. Lineaments were counted, measured and plotted in octants according to their direction, and a fracture density map of the country was prepared. on the basis of lineament intersection and density value, a map showing ``prospective sites'' for metal mineralization in Nepal was prepared. These possible sites were later compared with existing maps of geological, geophysical and geochemical anomalies. The result was encouraging because a considerable number of sites deduced by this remote sensing technique showed close resemblance with other anomalies identified by conventional methods. Taking into consideration the terrain and its difficult accessibility--requiring money and time to find anomalies for detailed study by any conventional method--it was decided that a second stage detailed study of some selected sites will be carried out based on remote sensing data. It is too early, however, to evaluate the real benefit of remote sensing techniques for mineral exploration in Nepal. It was found to be helpful in the sense that it provided the potential areas for detailed study and the answer to the questions ``where to look'' and ``how to look''--vital questions in any mineral exploration program of a developing country.
Remotely sensed mineralogy will likely play a large role in the selection of future Mars landed s... more Remotely sensed mineralogy will likely play a large role in the selection of future Mars landed science locations, and with the success of the OMEGA experiment on Mars Express (identification of sulfate, phyllosilicate minerals), the data from CRISM on MRO will also be important. One of the crucial challenges in this activity is how to identify promising targets from spatially coarse data for in situ investigation. We present an approach for systematic integration of data from remote sensing to rover scales. We incorporate data from the sample, to in situ, to regional remotely sensed data. We test the applicability of this approach to Mars using VNIR field- and remotely sensed spectra from Rio Tinto, Spain. The Rio Tinto has a diverse iron oxide and hydrous sulfate mineralogy in a very acidic environment and is considered a mineralogic and biologic analog for Mars, especially Terra Meridiani. We use remotely sensed Hymap data (8 m per pixel) to predict small areas with high mineral diversity, and then verify the identified locales through field work at the sample and in situ scales. We apply the Spectral Variance Index (SVI), a method which blends spatial and spectral components, to locate regions with increased mineral diversity. Remotely acquired data from the Hymap spectrometer (8 m per pixel) are binned into 25x25 pixel (or 200m x 200m) cells. We compute their mean and variance by wavelength and their expected spectral variance due to their albedo. Cells with a spectral variance significantly higher than their expected variance have more spectra variability than average, and thus are likely to have more mineralogic diversity. While this technique identifies areas of mineral diversity, it is less able to identify unique mineralogy. To catalog the mineralogy present at the Rio Tinto, we perform a Minimum Noise Function (MNF) followed by a Pixel Purity Index (PPI) function on the Hymap data. Pixels that are flagged by this process are unique in the scene and tend to represent pure mineralogy. Minerals thus identified include goethite, hematite, gypsum, hydrated Fe3+ sulfates including copiapite, hydrated Fe2+ sulfates including rozenite and melanterite, and various clay minerals. The SVI approach identifies areas of high mineralogic diversity in the Rio Tinto, and could also be applied to Mars orbital spectral datasets, such as OMEGA and CRISM. This exploration strategy for iron oxide and sulfate-rich environments over a range of spatial scales could allow us to pinpoint Rio Tinto-like deposits on Mars, a useful ability in the search for future landing sites of mineralogic and astrobiologic interest.
Remote sensing, the science of evaluating the earth and its systems from a distance, continues to... more Remote sensing, the science of evaluating the earth and its systems from a distance, continues to become more exact in its methods and more widely used and accepted as a tool for geological investigations. Nonetheless, methods of processing and analyzing remotely sensed data ...
The aim of the present study is to define the most suitable methodologies for ASTER data pre-proc... more The aim of the present study is to define the most suitable methodologies for ASTER data pre-processing and analysis in order to enhance peraluminous granitoid rocks in rugged and vegetated areas.The research started with raw image data pre-processing and continued with a comparison of satellite, field and laboratory data. The masking technique adopted to isolate rocky pixels was of fundamental importance to perform further analysis. An integration of density-sliced images and false colour composite images of Band Ratio, Relative Absorption Band Depth and Principal Component Analysis allowed us to generate a geological map that highlights a new granitoid body (Buraburi Granite) and the surrounding host rocks in the Dolpo region (western Nepal). The Buraburi Granite was mapped and sampled integrating remotely sensed ASTER data with analysis of rocks and minerals spectral signatures.The innovative approach that we have adopted considers the absorption features of particular lichen species (acidophilic). The results highlight the importance of considering acidophilic lichen means of detecting granitoid rocks. Furthermore, since peraluminous granitoids (i.e. Buraburi granite) have a considerable Al2O3 bulk rock content, the Muscovite Al–OH absorption peaks centred in the 6th ASTER band were also considered an important parameter for their detection.Field observations confirm the results of remote sensing analysis showing the intrusive relationship between the newly discovered 110 km2 granitoid body and the wall rocks of the Higher Himalayan Crystalline and the Tibetan Sedimentary Sequence.In conclusion, the proposed methods have great potential for granitoid mapping in vegetated and rough terrains, particularly those with climatic and geological conditions similar to the ones of the Southern Himalayan belt.► ASTER data has been successfully used in extreme terrain (rugged and vegetated). ► Rocky pixel extraction is fundamental for remote lithological discrimination. ► Acidophilic lichens spectra are a proxy for the remote detection of granitoid rocks. ► A previously unknown large granitoid body has been discovered.
The area under study covers an area of 640 km 2 , located in the southern part of Iranian Volcani... more The area under study covers an area of 640 km 2 , located in the southern part of Iranian Volcanic-Sedimentary Belt. ETM+ images have been used for alteration mapping. Satellit images can be used for enhancing the areas with hydroxyl and iron oxide minerals. However field checking has shown that this method is not able to enhance all the areas with hydrothermal alteration. At the same time many of the altered areas do not have good signature in the geophysical data. In order to recognize such areas integration of remote sensing and geophysical data can be helpful. The Darrehzar Cu deposit is chosen as a control area. The data analysis and integration of geophysical and remote sensing data is performed by using directed principal components. This technique is found to be useful for the delineation of hydrothermaly altered areas with more confidence.
Satellite remote sensing images can be interpreted to provide important information of large-scal... more Satellite remote sensing images can be interpreted to provide important information of large-scale natural resources, such as lands, oceans, mountains, rivers, forests and minerals for Earth observations. Recent advances of remote sensing technologies have improved the availability of satellite imagery in a wide range of applications including high dimensional remote sensing data sets (e.g. high spectral and high spatial resolution images). The information of high dimensional remote sensing images obtained by state-of-the-art sensor technologies can be identified more accurately than images acquired by conventional remote sensing techniques. However, due to its large volume of image data, it requires a huge amount of storages and computing time. In response, the computational complexity of data processing for high dimensional remote sensing data analysis will increase. Consequently, this paper proposes a novel classification algorithm based on semi-matroid structure, known as the parallel k-dimensional tree semi-matroid (PKTSM) classification, which adopts a new hybrid parallel approach to deal with high dimensional data sets. It is implemented by combining the message passing interface (MPI) library, the open multi-processing (OpenMP) application programming interface and the compute unified device architecture (CUDA) of graphics processing units (GPU) in a hybrid mode. The effectiveness of the proposed PKTSM is evaluated by using MODIS/ASTER airborne simulator (MASTER) images and airborne synthetic aperture radar (AIRSAR) images for land cover classification during the Pacrim II campaign. The experimental results demonstrated that the proposed hybrid PKTSM can significantly improve the performance in terms of both computational speed-up and classification accuracy.
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Papers by Erfin Elly