CATS Technological Hazards

CATS High Explosive Scenario

Example Scenario Description

High Explosive Blast Effects

CATS contains utilities to model the effects of high explosive (commonly referred to as HE) blasts and resulting consequences to the population, infrastructure, and critical facilities. Such explosions produce a blast wave that can destroy building structures and cause injury not only from the blast wave, but from flying debris. CATS is capable of modeling the propagation of the blast wave, and determining its effects both on building structures and the human body. HE results are especially illuminating when overlaid upon detailed maps (such as georeferenced satellite images) of buildings and facilities.

Example of a CATS High Explosive Blast simulation:

First, the user chooses the location of the event simply by clicking on the map at the point from which he wants the blast to originate. A GUI appears confirming this location:

Next, the HE model is easily launched from within CATS:

Inputs

Definition of hazardous incident or source is defined only by the location and severity of the explosion; the latter is expressed in terms of an amount of TNT in pounds . Different types of explosive materials are not modeled; only the pounds-of-TNT equivalent is input. In this case, the example is of a HE explosion near Union Station in Washington, D.C.
The user inputs all the incident data by using a simple GUI, an example of which is shown below. The latitude-longitude coordinates that appear in the GUI are those that the user chose in the step described above. If he wishes to change them in this GUI, he may do so.

Outputs

Output is displayed as color-coded "footprints" that are overlaid upon georeferenced maps. In this case, the output is overlaid on a tiff image (satellilte photograph) of Washington, D.C.
HE Footprints show the following types of blast effects damage:

Damage to Structures:

Extensive Structural Damage
Brick Walls
Breaking Glass
Electronic Equipment
Mechanical Equipment

Human Injury:

Eardrum Injury
Lung Damage (Onset Symptoms, Threshold Hemmorhage, and Severe Damage)
Injury from Flying Glass

The example below shows a footprint displaying results of a 20,000 pound TNT explosion near Union Station in Washington, D.C. Footprint countour damage levels are displayed in the accompanying legend. It can be seen that the explosion will cause glass to break a few blocks away from the blast point. The user can click on any point inside the footprint for a detailed presentation of the blast wave properties such as air pressure and blast radius in feet. The example shows these properties for Personnel Injury From Flying Glass: 7 psi, 515.7 ft.

Consequences Assessment

For CATS High Explosive scenarios, consequences assessment refers to determination of population at risk, infrastructure, and critical facilities lying within the extent of the hazard footprint.

Population at risk refers to the total population lying within each of the plume contours. (The population data is provided with CATS and is 1990 Census Data.) This utility provides a quick and easy way to determine the total number of persons who might be in harm's way. For the example shown above, the user may determine the population at risk in each of the plume contours. The output is provided in a text report. The population data is "residential", meaning where persons live, not where they work. Consequently, if a bomb exploded at nighttime, few would be at risk in downtown Washington.

Affected infrastructure is also provided in a text report, detailing numbers of infrastructure (whose types are selected by the user) lying within footprint areas. This example displays numbers of electronics parts stores and furniture stores lying with contour areas for Breaking Glass and Symptom Onset Lung Damage. Many more types of infrastructures (approximately 60 total) are available for examination.

Critical facilities are shown as map data, and their availability in the aftermath of an attack or accident is determined by their proximity to the hazard area. The HE footprint display figure (shown above as a footprint superimposed upon a sattelite photo of Washington, D.C.) shows that a 20,000 lb. equivalent of TNT set off at Union Station would not threaten the Capitol Building, for example.

CATS Example Scenarios