Earthquakes
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Hazard specific products
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Maps produced during a humanitarian response to earthquakes, visualising the seismic data and any data that may forecast the extent of physical damage and potentially act as a proxy for humanitarian impact. It may be combined with other thematic layers, notably with baseline population data to enable a rapid/early analysis of the population potentially affected.
Both
Situational.
At an early stage after the occurrence of a major earthquake with the potential to create damage and casualties. The necessary data will invariably be available within hours of the initial earthquake. Data and maps may be updated following aftershocks or to add additional analysis layers, including for example assessed landslide risk zones, vulnerable infrastructure (e.g. dams), or population baselines.
All responders, but particularly those operating across the wider affected area and including actors working on assessment processes and response planning and coordination.
The map will provide context to the potential scope and scale of earthquake. It shows them the location of the epicentre (and aftershocks) and the intensity in different areas. When this is shown with population data it will also give an indication of potentially where the most affected people will be. It will inform them of where potential search and rescue activity might be required.
Initial data, typically from United States Geological Survey (USGS) Earthquake alerts, will give basic indicators including the magnitude and location of the epicentre of the initial event and any aftershocks. This point data should be placed on the map first. It is not good practice to buffer circular rings around the epicentre as this may imply a spatially regular fall-off of damage which is very unlikely to reflect reality. As a large earthquake is “more appropriately described as a slip over a larger fault area” (USGS, see below), single points are poor representations of large earthquakes, so a map showing zones of ‘shake intensity’ provides more useful information. Analysed shake intensity zone data should be obtained mapped as soon as possible. Because this is modelled predictively rather and not ground truthed, it should be appropriately explained and have a caveat on maps. A suitable base map will normally include terrain and any available data on population distribution or population places.
Geophysical data is usually obtained from United States Geological Survey or others. This may include locations of reported epicentres of primary and aftershocks (as points), and modelled shake intensity (as polygons).
Data on predicted or actual landslides from various providers; but be cautious of the methods used to derive these as they may not be reliable.
Analysed satellite imagery to identify building damage; but be cautious because analysis methods may not have been standardised or reliable, and take special care to identify areas that have not been analysed.
