Description:
As part of a joint NASA/JPL response, ImageCat has produced the following products in response to the Nepal Earthquake: 1) building damage maps that estimate the number of buildings by damage state/class (slight, moderate, extensive and complete); 2) number of fatalities based on the percentage of collapsed/destroyed structures; 3) number of displaced persons (estimated as the number of people living in structures that were extensively damaged or destroyed) that were not fatally injured; and 4) rebuilding costs estimated from number of buildings in each damage state/class, the average building size, and the average building cost per square meter for each building type. These estimates are provided in ranges on a 500 square meter grid. With some validation completed, the estimated totals are:
- Extensively damaged or destroyed buildings: 225,000 to 450,000
- Fatalities: 9,000 to 22,000, with a mean estimate of 16,000.
- The total number of displaced persons: between 1 and 2 million.
- Rebuilding costs from building damage only (i.e., no infrastructure repairs are considered): between 2 and 3 billion USD.
Validation Process (which is ongoing): The April 25th 7.8 Gorkha Earthquake in Nepal occurred in an area with very few seismic stations. Ground motions from the main shock were estimated primarily using Ground Motion Prediction Equations (GMPEs) over a very large region, with a very high degree of uncertainty. To reduce the uncertainty, ground motions (PGA) were inferred using observations of building collapse from data generated by the National Geospatial Agency and building exposure estimates produced early in the disaster by ImageCat. In addition, building damage and fatality results were compared with estimates from the Government of Nepal (as recent as May 20th), both in aggregate and at the district level. The building damage functions used (modified damage functions from HAZUS) were applied to four (4) development types that are observed in Nepal: 1) sparsely populated, 2) rural, 3) dense development, and 4) urban development. Each region was classified (in part) using remotely-sensed imagery/data. Structural classifications (breakdown) were identified for these areas based on an extensive review of Kathmandu, a review of the World Housing Encyclopedia (EERI), various earthquake studies for Nepal, and web resources. Fatality estimates were calculated based on ATC 13 (Rojahn and Sharpe, 1985) building collapse and fatality models, and daytime occupancy percentages extracted from material published by the Asian Development Bank. For estimating rebuilding costs, we estimated the total area to be repaired or replaced based on average building footprint size, the height of each building category, and the average cost per square meter, as determined from published reports for the general area (EERI WHE reports). A sensitivity analysis was conducted using various assumptions on building size, ground motion variations, and rebuilding/repair costs. Furthermore, we overlaid other NASA products to ensure that any outliers (damaged areas) or anomalies could be explained by use of other independent data sources. Our validation process is ongoing; we are also introducing effects from the May 12th M7.3 aftershock in the next version of results.
Data Source(s):
- Brzev, S.N., Greene, M., Sinha, R. (2002). Rubble stone masonry walls with timber frame and timber roof, (Vol 18) Report. Retrieved from http://www.world-housing.net/WHEReports/wh100051.pdf
- D'Ayala, D. (2004). Traditional Nawari house in Kathmandu Valley, Report 99. EERI. World Housing Encyclopedia. Retrieved from http://www.world-housing.net/category/asia/nepal
- Jaiswal, K., Wald, D., & D'Ayala, D. (2011). Developing empirical collapse fragility functions for global building types. Earthquake Spectra, 27(3), 775-795.
- Kumar, A., & Sinha, R. (2002). Rural mud house with pitched roof, (Vol. 23). Report. Retrieved from http://www.world-housing.net/WHEReports/wh100056.pdf
- Kumar, A., Pundit, J. (2005). Timber Frame Brick House with Attic, (Vol 116) Report. Retrieved from http://www.world-housing.net/WHEReports/wh100113.pdf
- Marhatta, Y.B., Bothara, J.K., Magar, M.B., Chapagain, G., (2011). Pillar walaghar (URM infilled RC frame buildings. Report 145. EERI. World Housing Encyclopedia. Retrieved from http://www.world-housing.net/category/asia/nepal
- NGA (2015) All Damage Nepal May 8th, 2015. Points, shapefile. Retrieved from http://nepal.nga.opendata.arcgis.com/
- OCHA United Nations Office for the Coordination of Humanitarian Affairs. (2015) May 19th, 2015 Compiled Casualties and Damages from Reports of the Ministry of Home Affairs and Napoli Police, Nepal. Excel spreadsheet. Retrieved from https://data.hdx.rwlabs.org/dataset/official-figures-for-casualties-and-damage
- Open street Map, Nepal (2015), May 11, 2015. ESRI Shapefile. Retrieved from http://labs.geofabrik.de/nepal/
- Parajuli, Y.K., Bothara, J.K., Upadhyay, B.K. (2011). Traditional oval-shaped rural stone house, Report 47. EERI. World Housing Encyclopedia. Retrieved from http://www.world-housing.net/category/asia/nepal
- Parajuli, Y.K., Bothara, J.K., Upadhyay, B.K. (2011). Uncoursed rubble stone masonry walls with timber floor and roof, Report 74.EERI. World Housing Encyclopedia. Retrieved from http://www.world-housing.net/category/asia/nepal
- Rojahn, C. and Sharpe, R.L. (1985). "Earthquake damage evaluation data for California." Report No. ATC-13, Applied Technology Council, California.
- Trifunac, M.D., 1976. "A Note on the Range of Peak Amplitudes of Recorded Accelerations, Velocities, and Displacements with Respect to the Modified Mercalli Intensity Scale," Earthquake Notes, vol. 47, no. 1.
- Building exposure database and analysis credit: ImageCat
Link:
KMZ
Quick Web View: Quick web view
Web Mapping Service (WMS) Information: http://wms.imagecatinc.com/earthquake-nepal-displaced-persons-classes-20150522
Web Mapping Service (WMS) Layer Name: Extensively_Damaged_and_Destroyed_Buildings_per_500sq_m_classes_20150522
More Information: For more information about this product, visit: ImageCat
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