# Physical Vulnerability and Landslide Risk Assessment in Tegucigalpa City, Honduras
## 1 Introduction
### Study Area  
Tegucigalpa, the Municipality of the Central District (MCD), is the municipality in Honduras with the highest number of landslides. The city has undergone rapid expansion in recent years, resulting in the location of neighborhoods of the lowest social classes on the outskirts of the urban area. These areas are often on steeply sloping terrain, which makes them more susceptible to landslides [21]. In the MCD, single-story housing predominates and housing construction on several levels is still very scarce [21].  
In the period between 1966 and 2016, the MCD experienced 36% (237 events) of the total landslides nationwide, affecting 13,644 people, resulting in 55 casualties and the destruction of 875 homes [22]. Especially devastating were the landslides associated with Hurricane Mitch, which occurred in the last few days of October 1998 and caused events such as the El Berrinche landslide. These landslide events were both rotational and translational, and directly or indirectly affected the entire population of the city [23].  
After Hurricane Mitch, several studies were carried out to characterize landslide-prone areas. A critical review of landslide studies was conducted in a previous publication [24], resulting in the development of a new inventory of slow-moving translational and rotational landslides. The focus on slow-moving translational and rotational events was emphasized, due to the historical concentration of losses in the study area associated with these types of landslides. The study found that slow-moving translational and rotational landslides were primarily concentrated in colluvium deposits and residual soils. Consequently, a susceptibility map applying a bivariate statistical approach was developed, based on the colluvium and residual soil coverage. Using the success curve method, the study found that this susceptibility map was more effective in explaining the spatial distribution of translational and rotational landslides than previous susceptibility maps, with an area under the curve (AUC) of 88.64.  
Although different landslide studies have been conducted in the MCD, the city lacks access to a map identifying landslide risk [21]. This information is crucial for evaluating the significance of the issues related to these hazards and to analyze the costs and benefits of implementing measures to mitigate or manage them.  
The present study aims to assess the risk of landslides in the MCD and estimate the potential direct economic losses associated with them, taking into account physical vulnerability.  
The study area, which is shown in Figure 1, spans over 260 km\({}^{2}\) and includes the entire MCD urban sprawl. The MCD is situated on a plateau surrounded by steep slopes, with 62% of the study area having slopes greater than 20% [21]. The region experiences rainfall mainly between May and October, with an average annual rainfall of 870 mm [25].  
Figure 1: (**a**) Location of the MCD and (**b**) location of the study area.  
The study area is characterized by three main geological formations [26]: (i) the Valle de Angeles group, which is from the High Cretaceous period; consists of shale, sandstone, and reddish conglomerate; and is further divided into two formations--namely, the Villanueva Formation and the Rio Chiquito Formation; (ii) the Padre Miguel group, which is from the Middle Miocene period and consists of tuff and ignimbrite; and (iii) andesite and basalt, most likely from the Holocene period. Deposits of quaternary alluviums and colluviums are also found atop these formations, as shown in Figure 2.