|FAULTS AND DISCONTINUITIES|
Image credit: United States Geological Survey
Near Surface Geology
Faults and other geological discontinuities (joints, fractures, etc.) can be identified from a wide range of EO sensors and tools. DEM analysis is frequently the key method to identify and map these features, although analysis of optical and radar imagery (including multi-temporal analysis) can also be used to identify and assess these features in greater detail.
Products will vary according to particular user requirements and may vary widely in geographic scale and level of detail required.
Active faults can be identified and monitored by a range of techniques, with EO techniques forming an important component of seismic hazard studies.
Optical imagery and DEMs can help to identify faults (photogeomorphological analysis), including assessment of age (e.g., evidence of neotectonic fault activity from displacement or disturbance of Holocene sediments). This may include identification of both faults at surface and also recognising faults at depth (e.g., from identification of fault-propagation folds).
Change detection methods utilising SAR image couples (basic interferometry) or multi-temporal datasets (advanced interferometry) can identify ground deformation, surface rupture and fault motion (including co-seismic events). InSAR techniques are capable of identifying interseismic strain and can be beneficial in monitoring neotectonic faults. Other analytical techniques of change detection (using optical imagery) can also provide details of fault movement and provide input to seismic hazard assessments.
DEM data can be derived from assorted sources of EO data – both radar and optical, at a wide range of resolution (90 m to 1 m) and accuracy. See the Elevation product sheet for more details.
Products may include:
Additionally, supporting products may include:
Known restrictions / limitations
Cloud cover, dense vegetation and areas with thick soil cover reduces accuracy of assessment. Use of radar imagery can mitigate these limitations to some extent.
Lifecycle stage and demand
Pre-license: Information on structural geology to support decision-making on a prospect.
Exploration: Information to support geological mapping of surface and sub-surface, e.g., for use in reservoir modelling software and seismic interpretation.
Development: Information for planning and design of infrastructure, to support site selection, pipeline routeing and seismic hazard assessment (including active faulting) to determine hazards and risks in a proposed development area.
Production: Information to support monitoring of reservoirs or assets. May be required for post-event assessment, e.g., post-earthquake fault assessment to pipelines or other surface assets.
Decommissioning: Not typically required other than as a baseline record or if any ongoing monitoring is required.
Geographic coverage and demand
Demand is global.
Demand is in all terrain areas.
OTM:029 Prelicensing site selection
OTM:036 Geohazard exposure analysis
OTM:039 Selection of development sites
OTM:051 Identification of fault lines
HC:2101 Lineament mapping
Input data sources
Optical: VHR1, VHR2, HR1, HR2
Radar: VHR1, VHR2, HR1, HR2, MR1
Spatial resolution and coverage
Varies depending on input imagery used and client needs.
Low resolution DEM for basin wide exploration studies, higher resolution DEM and optical imagery (HR2 to VHR1) for development and infrastructure planning and design.
InSAR analysis resolutions are sensor dependent.
Minimum Mapping Unit (MMU)
Variable, depending on source data resolution and project requirements.
Accuracy / constraints
Varies depending on input imagery and user requirements.
Accuracy assessment approach & quality control measures
Professional judgement by comparison with any published geological mapping, published literature and reports.
Field mapping and validation.
Ground investigation, geophysics, boreholes and fault-trenching.
Frequency / timeliness
Varies depending on user requirements.
Observation frequency: Typically only one date is required and can be archive data, subject to project requirements. Image couples and multi-temporal data may be used for reservoir monitoring or for seismic analysis (e.g., InSAR stacks).
Timeliness of delivery: Usually off-the-shelf data can be utilised. Commissioned data may be required in some cases e.g., for collection of VHR1 stereo data for high resolution DEM production. Rapid delivery (<5 days) required in cases of post-earthquake event assessments.
Availability from commercial suppliers and other agencies.
New acquisitions can be requested globally for higher resolution data.
Archive products (DEM) available for public search.
Delivery / output format
Faults and Discontinuities
# of Pages:
Internal – Project consortium and science partners
External – ESA
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