Inventory of landslides triggered by an extreme rainfall event in Marche-Umbria, Italy, on 15 September 2022

This paper describes the event landslide inventory map produced to record the ground effects of the extreme rainfall event that hit Umbria-Marche, central Italy, on 15th September 2022. 

The rainfall event hit an area of ~5,000 km², with peak rainfall intensities of 419 mm in 9 hours, an exceptionally intense rainfall for this area. The event generated widespread flooding also outside the area affected by rainfall. The rainfall event produced widespread landslides across an area of nearly 1,000 km². As a direct consequence of floods and landslides, many roads were interrupted and extensive damages were recorded to structures and infrastructures. 

The landslide inventory presented is the result of an extensive reconnaissance field survey covering a large neighbourhood of the area affected by the highest rainfall intensity.

The inventory covers an area of 550 km² and includes 1,687 landslides, corresponding to an average density of about 3.1 landslides per square kilometre. Landslide size (Landslide Area, A_L in m²) is in the range ~1 m² < A_L < 5.7 × 10⁴ m². Overall, landslides cover an area of 1.1 km², which represents 0.2% of the Area of Interest (AOI). 

In the final inventory, a total of 1,243 landslides were mapped as polygons directly in the field, whereas the remaining 444 landslides were mapped as points (i.e. without information on landslide area). After post-processing activities, 512 polygons were transformed into points because their area was below the threshold of 225 m². Therefore, in the final map, 731 landslides are represented as polygons and 956 as points, ~54% of which kept the value of the original area.

This repository stores:

1. A polygon shapefile of the AOI
2. A polygon shapefile of the raw inventory
3. A point shapefile of the raw inventory
4. A polygon shapefile of the final inventory
5. A point shapefile of the final inventory

This dataset consistently supports the scale of 1:15 000.

As a consequence, all polygons smaller than 225 m² (i.e. a square of 1 mm per side in the map) in the raw data polygon layer were transformed into points because their size was too small to be represented as polygons at 1:15000 scale.