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In This Space

FAULTS AND DISCONTINUITIES

Image credit: United States Geological Survey

PRODUCT DESCRIPTION

Category

Component products

Near Surface Geology

N/A

Uses

  • Surface geology mapping - mapping geological features
  • Surface geology mapping - structural interpretation
  • Surface geology mapping - terrain evaluation and geo-morphology characterisation
  • Subsidence monitoring - land motion relating to fault lines or other causes
  • Surface geology mapping - engineering geological evaluation
  • Logistics planning and operations - facility siting, pipeline routing and roads development

Geo-information requirements

  • Terrain information
  • Topographic information
  • Lithology, geological and structural properties of the near surface
  • Surface and ground motion

Description

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:

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:

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:

  • Fault and discontinuity maps (vector or raster), geology maps, structural/tectonic maps, with/without stereo-net plots of structural groupings;
  • InSAR ground movement maps; and
  • Seismic hazard reports (including outputs of EO data/analysis).

Additionally, supporting products may include:

  • Shaded-relief maps - beneficial to highlight structural geology (raster product); and
  • DEM data.

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

Exploration

Development

Production

Decommission

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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.

Challenges Addressed

OTM:001  Identifying effect of fault reactivation

OTM:005  Monitoring natural fault movement

OTM:010  Monitoring ground movement along pipelines

OTM:011  Surface infrastructure movement relative to sub-surface

OTM:015  Geological and terrain base maps for development of environmental baseline

OTM:029  Prelicensing site selection

OTM:036  Geohazard exposure analysis

OTM:039  Selection of development sites

OTM:051  Identification of fault lines

OTM:052  Identify the cause of geological movement

HC:2101  Lineament mapping

HC:2201  Identify geological structure through landform

HC:2401  Identify geohazards and landscape change rates

HC:2501  Characterization of surface/near-surface structural geological properties for infrastructure planning

HC:3101  Baseline and monitoring of areas with active faults and subsidence

HC:3203  Management of surface impacts due to ground deformation from operations

HC:4301  Map and monitor induced seismic hazards

HC:5401  Monitor pipeline corridor hazards

PRODUCT SPECIFICATIONS

Input data sources

Optical: VHR1, VHR2, HR1, HR2

Radar: VHR1, VHR2, HR1, HR2, MR1

Supporting data:

  • Geological maps
  • Published literature and reports
  • Digital elevation models (DEM) Airborne geophysics
  • Air photo interpretation

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

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

Data type:

  • Raster
  • Vector (depending on customer needs)
  • Summary report

File format:

  • Geotiff
  • Shapefile or any other OGC standard file formats
  • Standard office formats

 

Download product sheet. 


Lead author:

Hatfield consultants/Arup

Peer reviewer:

OTM/WesternGeco

Author(s):

Manning

Document Title:

Faults and Discontinuities

# of Pages:

6

Circulation:

Internal – Project consortium and science partners

 

External – ESA

 

 

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