NATHAN hazard scores

Summary

Every natural hazard possesses its own unique characteristics and occurrence patterns. For example, volcanic explosions are predicted to happen only every few decades, based on tectonic movements, while tropical cyclones occur more frequently during El-niño oscillation cycles. Given the significant variations in how each hazard is measured, Munich Re has developed ranges for different types of hazard measurements. These ranges help convert the diverse scales into a universal 'Traffic light' risk assessment, allowing for a more standardized and comparable evaluation of the varying natural hazard risks across the board.

By adopting a range that spans from 'No or Very Low' to 'Very High,' Munich Re ensures that these differing natural hazard risks can be effectively compared and understood. This approach facilitates a more comprehensive assessment of risk levels associated with various hazards. For more information see the Munich Re website here

Note

1. The hazards assessed under NATHAN scores are different from Climate hazard scores. Munich Re uses historical data for NATHAN scores and models future climate scenarios for Climate hazard scores. Some NATHAN hazards may be worsened by climate change, like Hail or Wildfire, due to their interconnected nature.

2. Geophysical hazards like Earthquakes, Volcanoes, and Tsunamis are not directly affected by global warming. Their risk may increase over time due to factors like getting closer to recurrence intervals.

3. Munich Re calculates NATHAN hazard scores using chosen models, but these don't predict hazard occurrences. The risk zones are created through a specific calculation method, so the scales and risk levels may differ with other data providers.

Table: Hazard types and scales

Hazard	Indicator Definition	Munich Re Calculation Methodology
Earthquake	Minimum intensity or peak acceleration to be expected for an exceedance probability of 10% in 50 years or the intensity that is to be expected once in 475 years („return period“)	Calculated probable maximum intensity (MM: modified Mercalli scale) with the exceedance probability for medium subsoil conditions.
Volcanoes	Relative measure of risk caused by different types of volcanic eruptions, their strengths and return periods. Principal associated hazards: Ballistic debris av., shockwaves, lava flows, pyroclastic flows, gases, lahars, lightning, acid rain, tephra fall.	Based on the VEI (volcano explosivity index, US Geological Survey) and its annual return periods. Secondary effects that can occur as a result of the large-scale distribution of volcanic particles (e.g. climate impacts, supraregional ash deposits) are not considered.
Tsunami	Seismic sea waves and occur after strong seaquakes or large submarine landslides, often induced by earthquakes or volcanic eruptions in the sea or on the coast.	Zones based on 100m SRTM (Version 4.1) elevation model, simulating multiple wave heights for each coast and calculated the maximum expansion. Historical tsunami and earthquake data are also taken into account.
Tropical Cyclone*	Composite index representing the historical incidence and strength of cyclone activity at a given location, weighted in favor of recent events.	Probable maximum intensity with an exceedance probability of 10% in 10 years (equivalent to return period of 100 years).
Extratropical storm	Created in the transition region between subtropical and polar climatic zones. Cold polar air masses collide with tropical air masses, forming extensive low-pressure eddies. Projection of peak wind speeds in five different categories.	The probable maximum intensity with an average exeedance probability of 10% in ten years (equivalent to a „return period“ of 100 years). Only for areas with high frequency of extratropical storms (approx. 30°–70° north and south of the equator).
Hail	Based on frequency and intensity of hail storms. Heavy hailstorms usually triggered by wide cold fronts.	Based on global temperature and precipitation data, as well as global distribution of lightning activity. Munich Re don’t use statistics on hail events occurrences rather predicts atmospheric conditions inducing hailstorms.
Tornado	Occur worldwide at latitudes between 20° and 60°. Composite index representing the frequency and intensity.	Interpolated from meteorological data and amount of damage of Tornados at a given location, weighted in favor of recent events.
Lightning	Global frequency of lightning strikes per km2 and year recorded by satellites and ground-based lightning detection networks.	Frequency determined by counting the total number of lightning flashes.
Wildfire	Result of complex interaction between climatic conditions, vegetation, and topography linked with historical data on wildfires.	Aggregates data on influencing factors. The effects of wind, arson and fire-prevention measures are not considered.
River Flood*	The extent and depth of pluvial and fluvial flooding at a given location in a give year.	Current River Flood hazard zones from JBA data, projected River Flood hazard zones with return periods. Does not consider dams.
Flash Flood	Short-term events produced by thunderstorms with heavy rain over one area.	Frequency and intensity based on meteorological data, soil, terrain, and hydrographic data (slope and flow accumulation).
Storm Surge	Occur along sea coasts with constant strong wind from one direction causing rise in water level, above the predicted tide level.	Detailed calculation for coasts and large lake shores. Zones based on 90m MERIT Digital Elevation Model (DEM), taking into account wind speed and bathymetry (underwater depth of lake or ocean floors). Does not consider dykes.