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Explore the Earth, Maps and Satellite Images

Google Maps and Google Earth are very common platforms today to explore maps and satellite images of the earth. But there are many other ways to explore the earth. Some are listed here.  1.   Earth Explorer This map is developed by USGS helpful to obtain earth imagery across available geo-spatial data types. Users can navigate via interactive map or text search to obtain Landsat satellite imagery, Radar data, UAS data, digital line graphs, digital elevation model data, aerial photos, Sentinel satellite data, some commercial satellite imagery including IKONOS and OrbView3, land cover data, digital map data from the National Map, and many other datasets. Users can search by exact location via the interactive map or input specific coordinates to view what data types are available. 2.   Sentinel Hub This platform developed by  Sinergise has Sentinel, Landsat, and other Earth observation imagery easily accessible for browsing, visualization and analysi...

Seismic Survey: Notes of major uses

 Seismic Survey

  1. Suitable for mapping of layered sedimentary sequences

  2. Widely used in search of oil and gas.

  3. Small scale mapping of near surface sedimentary layers, location of water table, 

  4. Site investigation of foundation conditions (including depth of bedrock). In engineering site investigation, Vp and Vs measurement for near surface layers allows direct calculation of Poisson's ratio and estimation of elastic moduli, which provides valuable information on in situ geotechnical properties.

  5. Offshore geological surveys


Refraction

Reflection (most widely used geophysical technique)

  1. Large/regional scale experiments for study of the entire crust or lithosphere.

  2. Estimation of depth of bedrock in foundation site investigation.

  3. In engineering purpose, derive relation between velocity and hardness of rock for quarrying operations, nature of landfill materials.

  4. Exploration of underground water in conjunction with resistivity methods (as there is a large difference in velocity of dry and wet sediments.)

  1. Search of hydrocarbons, used in all stages of hydrocarbon exploration

  2. Vertical seismic profiling (VSP) is used at the stage of oil field development.

  3. High resolution studies of shallow geology

  4. High resolution reflection seismology is used in investigation of quaternary sedimentary sequences and detail mapping of concealed bedrock surfaces.

  5. Study of the entire continental crust and upper mantle.


Seismic reflection  in Hydrocarbons exploration
  • Initial surveys along widely spaced profile lines covering large areas for regional geology and enable plan of detail follow up survey.
  • Detail reflection survey in areas of interest/prospective targets found from initial stage.It involves closely spaced profile lines and high density of profile intersection to define useful structures. Initial interpretation involves structural mapping to identify structural closures and the identified closures need a second round of detail survey to select location of exploration borehole. 3D survey may be used if unsoed by 2D data.
  • Exploration boreholes are sited on seismic lines sp borehole logs can be correlated directly with local seismic stations.
  • Refinement of seismic data from additional seismic profiles. Seismic modelling can be used to obtain detailed information on geometry of reservoir and internal lithological variation that may affect HC yield. 4D surveys can detect unexploited arrears in a producing field.

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Explore the Earth, Maps and Satellite Images

Google Maps and Google Earth are very common platforms today to explore maps and satellite images of the earth. But there are many other ways to explore the earth. Some are listed here.  1.   Earth Explorer This map is developed by USGS helpful to obtain earth imagery across available geo-spatial data types. Users can navigate via interactive map or text search to obtain Landsat satellite imagery, Radar data, UAS data, digital line graphs, digital elevation model data, aerial photos, Sentinel satellite data, some commercial satellite imagery including IKONOS and OrbView3, land cover data, digital map data from the National Map, and many other datasets. Users can search by exact location via the interactive map or input specific coordinates to view what data types are available. 2.   Sentinel Hub This platform developed by  Sinergise has Sentinel, Landsat, and other Earth observation imagery easily accessible for browsing, visualization and analysi...

Geological Maps of Nepal

 List of geological maps different parts of Nepal . 1. Geological Map of Nepal 2.  Geological Maps Of Seven Provinces, Nepal 3.  Photogeological Map of Central Nepal (Stocklin and Bhattarai, 1982). 4. Geological maps of 1:50,000  of different parts of Nepal published by DMG. 5. Engineering Geological and Environmental maps of different cities of Nepal published by DMG. 6.  Mineral Resources map of Nepal 7.  Epicenter map of Nepal Himalaya

Historical Earthquakes of Nepal

This is the list of some historical earthquakes of Nepal compiled from various sources. References: National Society for Earthquake Technology-Nepal (NSET) Pandey, M.R. & Molnar, P. (1988). "The Himalaya, its tectonic environment, and seismicity" Tiwari, Sudarshan. (1992). "The Brick and the Bull: An Account of Handigaon" Bilham, R. et al. (1995). "The Kathmandu Valley earthquakes of 1833 and 1834" Ambraseys, N.N. & Douglas, J. (2004). "Magnitude Calibration of North Indian Earthquakes" United States Geological Survey (USGS) Earthquake Information Bajracharya, B. (2001). "Earthquake Risk Reduction in Nepal" Udayapur Earthquake: NSET Report, 1990 Government of Nepal, National Planning Commission (2015). "Post-Disaster Needs Assessment" UN Office for the Coordination of Humanitarian Affairs (OCHA), 2015 Gorkha Earthquake United Nations Development Programme (UNDP), 2015