Natural Hazards & Risk
A hazard map is not a risk map, and the difference is arithmetic.
Risk is three things multiplied: a hazard with a probability, the people and buildings in its way, and how badly they fare when it arrives. Most published "risk maps" are one scenario of the first term, coloured red. These guides start with the three terms and with what a return period actually claims; then download an earthquake catalogue, fit a Gutenberg-Richter relation and a flood frequency curve, read a ShakeMap, map burn severity and fire perimeters, build a landslide susceptibility index, count who is exposed, and integrate the whole thing into an expected annual damage — with the fixes for counts that rise with the network, return periods read as schedules, severity outside the fire, exposure counted twice and nodata read as zero.
Step fifteen is where the path pays off: hazard maps, exposure and a damage curve become one number per year that can be compared between places. Everything before it exists to make that number defensible, and the five fixes after it are the ways it gets published wrong.
Start here
The cornerstone guide — the whole workflow end to end. Everything after it goes deeper into one part of it.
Step 1 Hazard, exposure and vulnerability explained: what "risk" means in a GIS hazard exposure vulnerability risk Begin the path →The full path, in order
The concepts underneath the work, then each task, then the errors that task produces. Work down, or jump to the step you need.
- Return periods and annual exceedance probability explained return period annual exceedance probability 🧭 Concept
- Flood hazard maps explained: depth, extent and which flood they describe flood hazard map explained 🧭 Concept
- Earthquake catalogues explained: magnitudes, completeness and declustering earthquake catalogue explained 🧭 Concept
- Burn severity explained: NBR, dNBR and what the classes mean burn severity dnbr explained 🧭 Concept
- Landslide susceptibility explained: what the map is and is not landslide susceptibility explained 🧭 Concept
- How to download and map an earthquake catalogue in Python download earthquake catalogue python ⚙️ How-To
- How to estimate b-value and completeness in Python gutenberg richter b value python ⚙️ How-To
- How to read a USGS ShakeMap and find who was shaken read usgs shakemap python ⚙️ How-To
- How to fit return periods to annual maxima in Python fit return period annual maxima python ⚙️ How-To
- How to work with fire perimeter data in Python fire perimeter data python ⚙️ How-To
- How to map burn severity with dNBR in Python map burn severity dnbr python ⚙️ How-To
- How to build a landslide susceptibility index in Python landslide susceptibility index python ⚙️ How-To
- How to count buildings and people exposed to a hazard zone count people in hazard zone python ⚙️ How-To
- How to combine hazard, exposure and vulnerability into a risk score expected annual damage python ⚙️ How-To
- Earthquake counts rise over time in my catalogue earthquake counts rise over time 🔧 Fix
- The 1-in-100-year flood happened twice in ten years 1 in 100 year flood twice 🔧 Fix
- dNBR shows burn severity outside the fire perimeter dnbr change outside fire perimeter 🔧 Fix
- Exposure counts are double-counted or missed exposure double counted hazard zones 🔧 Fix
- A hazard raster's nodata is read as zero hazard raster nodata as zero 🔧 Fix
Topics this path covers
A path is a route; a topic is everything the site has on a subject. Open a topic to see the guides this path skips.