This article refers to the use of computers to estimate losses caused by disasters. For other meanings of the word catastrophe, including catastrophe theory in mathematics, see catastrophe (disambiguation). Catastrophe modeling (also known as cat modeling) is the process of using computer-assisted calculations to estimate the losses that could be sustained due to a catastrophic event such as a hurricane or earthquake. Cat modeling is especially applicable to analyzing risks in the insurance industry and is at the confluence of actuarial science, engineering, meteorology, and seismology. Catastrophes/ Perils Natural catastrophes (sometimes referred to as "nat cat") that are modeled include: Hurricane (main peril is wind damage; some models can also include storm surge and rainfall) Earthquake (main peril is ground shaking; some models can also include tsunami, fire following earthquakes, liquefaction, landslide, and sprinkler leakage damage) severe thunderstorm or severe convective storms (main sub-perils are tornado, straight-line winds and hail) Flood Extratropical cyclone (commonly referred to as European windstorm) Wildfire Winter storm Human catastrophes include: Terrorism events Warfare Casualty/liability events Forced displacement crises Cyber data breaches Lines of business modeled Cat modeling involves many lines of business, including: Personal property Commercial property Workers' compensation Automobile physical damage Limited liabilities Product liability Business Interruption Inputs, Outputs, and Use Cases The input into a typical cat modeling software package is information on the exposures being analyzed that are vulnerable to catastrophe risk. The exposure data can be categorized into three basic groups: Information on the site locations, referred to as geocoding data (street address, postal code, county/CRESTA zone, etc.) Information on the physical characteristics of the exposures (construction, occupation/occupancy, year built, number of stories, number of employees, etc.) Information on the financial terms of the insurance coverage (coverage value, limit, deductible, etc.) The output of a cat model is an estimate of the losses that the model predicts would be associated with a particular event or set of events. When running a probabilistic model, the output is either a probabilistic loss distribution or a set of events that could be used to create a loss distribution; probable maximum losses ("PMLs") and average annual losses ("AALs") are calculated from the loss distribution. When running a deterministic model, losses caused by a specific event are calculated; for example, Hurricane Katrina or "a magnitude 8.0 earthquake in downtown San Francisco" could be analyzed against the portfolio of exposures. Cat models have a variety of use