9.4 Remote Sensing and Satellite-based Techniques
4 min read•july 30, 2024
Remote sensing revolutionizes volcano monitoring by using electromagnetic radiation to gather data from afar. It offers global coverage, continuous monitoring, and safety in hazardous areas. Satellites and aircraft collect crucial information on surface changes, gas emissions, and .
Satellite techniques like , , and provide valuable insights into volcanic activity. These methods help detect changes, map features, and interpret data, complementing ground-based monitoring for a comprehensive understanding of volcanic processes and improved eruption forecasting.
Remote sensing for volcano monitoring
Principles and applications
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Frontiers | Remotely Sensed Deformation and Thermal Anomalies at Mount Pagan, Mariana Islands View original
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Frontiers | Remotely Sensed Deformation and Thermal Anomalies at Mount Pagan, Mariana Islands View original
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Frontiers | Thermal Remote Sensing for Global Volcano Monitoring: Experiences From the MIROVA System View original
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Frontiers | Mapping Volcanic Deposits of the 2011–2015 Etna Eruptive Events Using Satellite ... View original
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Frontiers | Remotely Sensed Deformation and Thermal Anomalies at Mount Pagan, Mariana Islands View original
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- Remote sensing acquires information about an object or phenomenon without physical contact using electromagnetic radiation (visible light, infrared, radio waves)
- Monitors volcanic activity, detects changes in Earth's surface, provides early warning of potential eruptions
- Satellites and aircraft with remote sensing instruments collect data over large areas, including inaccessible or dangerous regions near active volcanoes
- Creates digital elevation models (DEMs), maps lava flows and ash deposits, monitors changes in volcanic gas emissions and thermal anomalies
Advantages and limitations compared to ground-based monitoring
- Advantages of remote sensing:
- Provides global coverage and monitors volcanoes in remote or inaccessible areas
- Enables continuous or frequent data acquisition, allowing for near-real-time monitoring
- Offers a synoptic view of volcanic systems, identifying regional patterns and trends
- Allows non-invasive and safe observation of hazardous volcanic environments
- Limitations of remote sensing:
- Depends on weather conditions (cloud cover) which can obscure satellite observations
- Has limited spatial and temporal resolution compared to ground-based instruments
- Measures volcanic processes indirectly, requiring careful interpretation and validation with ground-truth data
- Incurs high costs for satellite missions and data processing infrastructure
- Ground-based monitoring techniques (seismometers, GPS, gas sensors) provide direct, high-resolution measurements but have limited spatial coverage and can be vulnerable to damage during eruptions
- Integrating remote sensing and ground-based monitoring is often the most effective strategy for volcano monitoring and hazard assessment
Satellite techniques for volcano monitoring
Thermal infrared (TIR) imaging
- Measures heat emitted by volcanic features (lava flows, hot springs, fumaroles)
- Detects thermal anomalies and estimates lava flow rates and volumes
- Thermal anomalies appear as bright spots or areas of elevated temperature, indicating increased heat flow from the volcano
- The appearance or growth of thermal anomalies can signal impending eruptions or changes in volcanic activity
Synthetic Aperture Radar (SAR)
- Uses microwave radiation to create high-resolution images of Earth's surface
- Penetrates clouds and operates day and night, useful for monitoring volcanoes in remote or frequently cloudy areas
- SAR interferometry () compares multiple SAR images to detect surface deformation (ground swelling, subsidence), indicating magma movement beneath a volcano
- Time-series analysis of SAR data reveals patterns and trends in volcanic activity, such as gradual deformation leading up to an eruption
Ultraviolet/Visible (UV/VIS) spectroscopy
- Measures absorption and scattering of sunlight by volcanic gases (sulfur dioxide, ash particles)
- Estimates gas emission rates and tracks volcanic plumes
- Instruments used for UV/VIS spectroscopy include the Ozone Monitoring Instrument (OMI) and the Tropospheric Monitoring Instrument (TROPOMI)
- Changes in gas emissions detected by UV/VIS spectroscopy can indicate variations in volcanic activity and magma degassing
Interpreting remote sensing data of volcanoes
Detecting changes in volcanic activity
- Thermal anomalies in TIR images indicate increased heat flow and potential impending eruptions
- appear as bright, elongated features in visible and infrared satellite imagery, providing information about eruption intensity, duration, and wind conditions
- Time-series analysis reveals patterns and trends (gradual increase in thermal output or gas emissions before an eruption)
- Integrating remote sensing data with ground-based observations (seismic, deformation data) provides a comprehensive understanding of volcanic processes and improves eruption forecasting
Mapping volcanic features and products
- Digital elevation models (DEMs) created from remote sensing data help map volcanic topography and identify structural features (craters, calderas, faults)
- Lava flow and ash deposit extent can be mapped using visible and infrared imagery, aiding in hazard assessment and response planning
- Monitoring the growth and evolution of lava domes and flows using high-resolution satellite imagery helps assess the direction and rate of lava advancement
- Comparing pre- and post-eruption remote sensing data allows for the quantification of erupted volumes and the identification of landscape changes (new cones, collapsed sectors)
Remote sensing vs ground-based monitoring
Complementary nature of remote sensing and ground-based techniques
- Remote sensing provides a broad, synoptic view of volcanic systems, while ground-based monitoring offers high-resolution, localized measurements
- Satellite data can guide the placement of ground-based instruments in key locations and help interpret local observations in a regional context
- Ground-based data can validate and calibrate remote sensing measurements, improving their accuracy and reliability
- Combining remote sensing and ground-based data through data assimilation techniques enhances the understanding of volcanic processes and the accuracy of eruption forecasting models
Importance of an integrated monitoring approach
- No single monitoring technique can provide a complete picture of volcanic activity; an integrated approach is necessary for effective volcano monitoring and hazard assessment
- Integrating remote sensing, ground-based monitoring, and numerical modeling improves the understanding of volcanic systems and the ability to forecast eruptions
- An integrated approach allows for the cross-validation of data from different sources, reducing uncertainties and increasing confidence in monitoring results
- Combining multiple data types (thermal, deformation, gas emissions, seismic) through multi-parameter analysis can provide insights into the complex, interconnected processes driving volcanic activity
- Integrated monitoring networks that include both remote sensing and ground-based components are essential for the development of early warning systems and the mitigation of volcanic risks
Key Terms to Review (20)
Ash plumes: Ash plumes are clouds of volcanic ash that are ejected into the atmosphere during explosive volcanic eruptions. These plumes can rise several kilometers into the air, affecting air quality, aviation safety, and climate. The study of ash plumes is critical for understanding volcanic activity and its potential impacts on the environment and human activities.
Change detection: Change detection is a process used in remote sensing to identify differences in the state of an object or phenomenon by observing it at different times. This technique plays a critical role in monitoring environmental changes, urban development, and natural disasters by comparing satellite images taken at various intervals to highlight alterations in land cover, vegetation, and other features.
Data fusion: Data fusion is the process of integrating multiple sources of data to produce more accurate and comprehensive information than what can be obtained from any individual source. This technique is essential in remote sensing and satellite-based applications, as it allows researchers to combine various data types such as imagery, sensor readings, and geographical information to enhance the understanding of volcanic activity and other geological phenomena.
European Space Agency: The European Space Agency (ESA) is an intergovernmental organization dedicated to the exploration of space, founded in 1975. It plays a critical role in the advancement of satellite-based techniques, which are essential for remote sensing and monitoring various natural phenomena, including volcanic activity and earth sciences.
Georeferencing: Georeferencing is the process of associating spatial data with a specific location on the Earth's surface, often using geographic coordinates like latitude and longitude. This technique is crucial for integrating and analyzing data from various sources in remote sensing and satellite imagery, ensuring that the information aligns accurately with real-world locations.
Image classification: Image classification is the process of categorizing and labeling pixels in an image to identify specific features or objects within that image. This technique is particularly crucial in analyzing satellite and aerial imagery, allowing for the extraction of meaningful information about land use, vegetation, and geological features. By utilizing algorithms and machine learning techniques, image classification helps transform raw image data into actionable insights.
InSAR: InSAR, or Interferometric Synthetic Aperture Radar, is a remote sensing technique that uses radar images to measure ground deformation with high precision. By analyzing the phase differences between radar signals from multiple satellite passes, it can detect minute changes in the Earth's surface, making it invaluable for monitoring volcanic activity, earthquakes, and land subsidence. This technology combines radar imaging and interferometry, providing crucial data for understanding ground movements and hazards.
Landsat Imagery: Landsat imagery refers to the satellite images collected by the Landsat program, which has been capturing data about Earth's surface since 1972. This imagery provides critical information for monitoring land use, vegetation, and natural resources, making it an essential tool in remote sensing and satellite-based techniques for environmental studies.
Lava flow dynamics: Lava flow dynamics refers to the study of how molten rock (lava) moves and behaves as it erupts from a volcano. This field examines factors like viscosity, flow rate, topography, and cooling processes, which influence the shape, speed, and path of lava flows. Understanding lava flow dynamics is crucial for assessing volcanic hazards and predicting the potential impact on surrounding areas.
MODIS: MODIS, which stands for Moderate Resolution Imaging Spectroradiometer, is a key instrument aboard NASA's Terra and Aqua satellites. It plays a crucial role in monitoring and studying the Earth's environment, including volcanic activity, by capturing high-resolution images in multiple spectral bands. This capability allows scientists to analyze various geophysical and biophysical processes, making it a vital tool in both historical and contemporary volcanology research.
NASA: NASA, or the National Aeronautics and Space Administration, is a U.S. government agency responsible for the nation's civilian space program and for aeronautics and aerospace research. Established in 1958, NASA plays a crucial role in advancing technology and knowledge about Earth's atmosphere, space, and celestial bodies through innovative missions and scientific research.
Pixel resolution: Pixel resolution refers to the amount of detail an image holds, typically described by the number of pixels contained in each dimension that can be displayed on a screen or in an image. Higher pixel resolution means more detail and clarity in images, making it crucial for applications like remote sensing and satellite imagery, where precise details are necessary for analyzing and interpreting the Earth's surface.
Risk mapping: Risk mapping is the process of identifying, assessing, and visualizing potential hazards and their impacts on people, property, and the environment. This technique utilizes various data sources to create a graphical representation of risk levels in different areas, aiding in disaster preparedness and response efforts.
Spectral signature: A spectral signature is a unique pattern of reflectance and absorption characteristics of a material across different wavelengths of the electromagnetic spectrum. This pattern allows scientists to identify and differentiate materials, including minerals, vegetation, and water bodies, based on their specific spectral responses when observed through remote sensing technologies. The analysis of spectral signatures is crucial for applications such as land use mapping, environmental monitoring, and mineral exploration.
Synthetic aperture radar: Synthetic aperture radar (SAR) is a form of radar technology used to create high-resolution images of landscapes and objects, particularly from aerial or satellite platforms. This technique takes advantage of the motion of the radar sensor to simulate a larger antenna, allowing for improved imaging capabilities in remote sensing applications. SAR is especially valuable in studying Earth’s surface changes, including natural disasters and land deformation.
Synthetic aperture radar interferometry: Synthetic aperture radar interferometry (InSAR) is a remote sensing technique that uses radar signals to create detailed images of the Earth's surface and measure ground displacement. By comparing radar images taken at different times, InSAR can detect subtle changes in the landscape, making it a powerful tool for monitoring geological hazards like earthquakes and volcanic activity. This method combines radar technology with advanced signal processing to enhance image resolution and detect changes over time.
Thermal anomalies: Thermal anomalies are localized areas where the temperature deviates significantly from the surrounding environment, indicating potential geological activity or changes. These temperature differences can reveal vital information about subsurface processes, such as volcanic activity or geothermal systems, and can be detected through various remote sensing techniques, including satellite imagery.
Thermal infrared imaging: Thermal infrared imaging is a remote sensing technique that detects the infrared radiation emitted by objects, enabling the visualization of temperature variations on Earth's surface. This technology is crucial for monitoring volcanic activity, as it provides valuable data on heat sources, lava flows, and thermal anomalies that might indicate impending eruptions.
Uv/vis spectroscopy: UV/Vis spectroscopy is an analytical technique that measures the absorption of ultraviolet and visible light by a substance to identify its chemical composition and concentration. This method is particularly useful in remote sensing and satellite-based techniques, as it enables scientists to analyze the spectral characteristics of materials on Earth from a distance, facilitating the study of various environmental phenomena, including volcanic activity.
Volcanic eruption forecasting: Volcanic eruption forecasting is the process of predicting volcanic activity and potential eruptions using various scientific methods and techniques. This involves analyzing data from a variety of sources, including geological studies, seismic activity, gas emissions, and remote sensing technologies, to assess the likelihood of an eruption occurring. Accurate forecasting is crucial for risk assessment and disaster preparedness in areas surrounding active volcanoes.