Keywords

1 Introduction

The goal of the Sendai Framework for Disaster Risk Reduction is to “prevent new and reduce existing disaster risk through the implementation of integrated and inclusive economic, structural, legal, social, health, cultural, educational, environmental, technological, political and institutional measures that prevent and reduce hazard exposure and vulnerability to disaster, increase preparedness for response and recovery, and thus strengthen resilience” (UNISDR 2015: 12). This should be achieved by implementing its four priorities for action: Priority (1) Understanding disaster risk; Priority (2) Strengthening disaster risk governance to manage disaster risk; Priority (3) Investing in disaster risk reduction for resilience; and Priority (4) Enhancing disaster preparedness for effective response and to “Build Back Better” in recovery, rehabilitation, and reconstruction. Although the Science and Technology Community plays a significant role in attaining all of them, by its nature, understanding disaster risk (Priority 1) is strongly associated with scientific commitment.

The accomplishment of this priority at the national and local levels requires that landslide experts promote, among other issues, “national strategies to strengthen public education and awareness in disaster risk reduction, including disaster risk information and knowledge, through campaigns, social media, and community mobilization, taking into account specific audiences and their needs” (UNISDR 2015: 15).

The success of this endeavor, especially regarding landslide disaster risk, relies on different strategies and initiatives, including the Sendai Partnerships 2015–2025 and the Kyoto Landslide Commitment 2020 for Global Promotion of Understanding and Reducing Landslide Disaster Risk (KLC2020). These undertakings promote landslide research and capacity building, including education for disaster risk reduction, especially in developing countries (Sassa 2015, 2016). Of particular relevance for this chapter is the priority Action 5 of the KLC2020, which seeks to enhance open communication within society through integrated research, capacity building, knowledge transfer, awareness raising, training, and educational activities to enable societies to develop effective policies and strategies for reducing landslide disaster risk, to strengthen their capacities for preventing hazards to develop into major disasters, and to enhance the effectiveness and efficiency of relief programs (Sassa 2018, 2020).

In light of these concerns, this study focused on analyzing the expansion of the urban area of a district highly exposed to landslides in the municipality of Teziutlán, Puebla, and its relationship with the spatial-temporal distribution of this type of process. In the following sections, this chapter addresses the need to reinforce disaster risk landslide awareness on a continual basis. A broad reflection on landslide exposure and awareness is provided in section two, followed by a description of the studied area in sect. 3. Section 4 deals with the methodology. Results are provided in sect. 5 while concluding remarks are presented in sect. 6.

2 Landslide Exposure and Awareness

The terms exposure and awareness are key for understanding disaster risk. According to the Oxford dictionary, while exposure involves being in a place or situation without protection from something harmful or unpleasant, awareness means knowing something, knowing that something exists and is important.

Exposure has been defined by UNISDRR (2017) as the situation of people, infrastructure, housing, production capacities, and other tangible human assets located in hazard-prone areas. In other words, it involves the component of location given by specific geographic coordinates to represent the dimension of space and its constituents that can be potentially affected by a hazard, in this case, landslides. Therefore, the term reflects a specific itemization of humanness, socio-economic, material, cultural, and environmental assets that can be easily affected by hazards of diverse origins. Awareness of landslide exposure involves knowing that the potential occurrence of a landslide in a specific place is significant, and therefore information, knowledge, and actions must be developed.

Awareness of landslide disaster risk (i.e., Solana and Kilburn 2003) is strongly linked to people’s perception of landslides (Alcántara-Ayala 2018). This topic is quite complex (Slovic 1987; Pidgeon et al. 1992) and needs to be properly addressed. However, although its analysis is beyond the scope of this chapter, it can be said that the perception of risk involves the explanations that people construct and conceive of understanding the dynamics of the complex interactions that give rise to risk; in other words, the latent or potential condition for one or several disasters to occur. These explanations are based on experiences (Barnett and Breakwell 2001), beliefs (Aucote et al. 2010), social and cultural frameworks, gender (Gustafson 1998), feelings, and needs (see Hernández-Moreno and Alcántara-Ayala 2017; Alcántara-Ayala and Moreno 2016).

Quite often, people reject the possibility of a disaster being repeated. The myth of personal invulnerability (Joffe and Joffé 1999) also plays a role in disaster risk perception and, thus, awareness. This involves recognizing the presence of a situation that can be regarded as a risk. Still, if it occurs, it is believed to impact somebody else, such as neighbors or people from another city, but those at risk are safe. This idea of avoiding acceptance (Finlay and Fell 1997) leads to a lack of awareness and preparedness, increasing vulnerability and disaster risk.

Furthermore, disaster risk perception is also associated with understanding the spatial and temporal dimensions of the hazards, in this case, landslides.

The problems of enacting a single long-term future associated with disaster risk management involve perceptions of people’s at-risk and quotidian priorities. While daily security and subsistence are in people’s minds, the occurrence of landslides is, by no effect, a priority. Nonetheless, understanding landslide disaster risk in areas exposed to this type of hazard requires continuous raising of awareness, particularly when no disasters have occurred.

How people measure time concerning the occurrence of disasters is very complex and deserves in-depth study. Based on field observations in provincial areas, it is recognized that the future is often measured based on personal, family, and collective interest events. Patronal festivities and local traditions are eagerly awaited, where medicinal artisans work with celebrants to forget the problems of reality, including those derived from disaster risk.

3 Studied Area

Teziutlán is in the northeast of Puebla province, in the Central East part of Mexico (Fig. 1). It has a population of 103,583. It comprises 32 localities, of which 62,849 people live in the municipal capital and the rest in towns of various sizes (INEGI 2021). Historically, this area has endured several disasters associated with rainfall-induced landslides that result from the combination of high-susceptible lithology and increasing exposure of vulnerable communities (Alcántara-Ayala 2004). Pyroclastic deposits generated from the Caldera de Los Humeros, along with overlaying sedimentary and metamorphic rocks, are the most critical lithological units susceptible to landsliding (Murillo-García et al. 2019).

Fig. 1
A map of the northeast of Puebla province indicates Teziutlan. A map of Teziutlan highlights the study area. A map of Puebla in the bottom left corner highlights Teziutlan.

Location of the studied area

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The most severe landslide-associated disaster in this region occurred in October 1999. Dozens of landslides affected Teziutlán, where more than one hundred people lost their lives, and the economic impact was very high. Diverse investigations have documented various aspects of this disaster and the ingredients of landslide disaster risk in the municipality (Alcántara-Ayala et al. 2017, 2018). These include understanding hazards (Garnica-Peña and Alcántara-Ayala 2017), vulnerability, exposure (Garnica-Peña et al. 2021a, b), and different mechanisms to reduce landslide disaster risk (Alcántara-Ayala and Moreno 2016).

In Teziutlán, disasters associated with landslides triggered by rainfall (Alcántara-Ayala 2004) continue to be viewed as an external, exogenous event during which the population plays no role other than cooperating during the response. Therefore, in addition to past efforts, there is a clear need to raise sustained mechanisms of landslide disaster risk awareness at the local level, at the time people at risk are embedded in activities that capture their interest, regardless of their nature.

4 Methodology

The analysis is based on material collected from 2007 to 2023. A methodology combining the analysis of an available orthophoto from the National Institute of Statistics and Geography and images produced by Unmanned Aerial Vehicles (UAVs) was adopted to distinguish between the occurrence of rainfall-triggered landslides and the effects of the expansion of the urban area (Fig. 2).

Fig. 2
A flowchart includes take-off site selection, selected site, missions, North-South and West-East missions, 739 and 1866 photos, point of interest and manual missions 2023, 482 photos, Bentley context capture processing, digitization of urban sprawl using Arc G I S, and expansion of the urban area.

Strategy for the analysis of the expansion of the urban area

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4.1 Aerial Survey Using UAVs

A couple of flights were made in the study area. The mobile application, Map Pilot Pro, was used in both cases. In this application, the area to be flown was defined, and parameters such as the flight height above the ground were established (which defined, together with the size of the image, the resolution of the acquired images), superimposition or frontal and lateral overlap, and movement speed of the equipment. Due to the size of the surface, it was necessary to use four batteries on each mission to cover the full area at the established height.

Sometimes, in mountain zones with dense vegetation, a lack of information or coverage of ground conditions results when flights are carried out in only one direction. To avoid data gaps in aerial photography, UAV missions consisted of lines in a North-South and East-West direction to successfully cover the entire study area. DJI Phantom 4 Pro equipment, consisting of a camera with a 1″ sensor and 20-megapixels effective resolution, was used for these missions. It also had an average autonomy of 20 min per battery.

Once the images were acquired, they were processed in the Bentley ContextCapture software to obtain various products such as orthophotos, point clouds, digital surface models (DSM), and three-dimensional triangular mesh models. For this study, only photographic mosaics were used. The processing consisted of the following stages: (a) define the control points (ground control points), mooring points (tie points), and scale points were first defined; (b) aerial triangulation was undertaken; (c) a 3D mesh was then generated; and lastly, (d) orthophotos and digital surface models were created.

For the flight carried out in April 2017 with the Phantom 4 Pro equipment, the Map Pilot Pro application (Maps Made Easy©) was used. The flight had a W-E direction, at 150 m above the ground, with an 80% frontal and 80% lateral overlap. Additionally, an N-S flight was carried out, with a height above the ground of 150 m and an 80% frontal and 80% lateral overlap. The number of photos acquired was 739, and the orthophoto was generated at 9 cm-resolution.

The Map Pilot Pro application (Maps Made Easy©) was used for the flight carried out in February 2023. The W-E and N-E flights were carried out 100 m above the ground, with a frontal and lateral overlap of 80%. Some 1866 photos were acquired. Additionally, the FPVCameraforDJI application was used with a Point of Interest (POI) flight mode to take oblique shots. Flight 1 was carried out at 50 and 60 m above the ground, with a radius of 55 m and 70 m and an inclination of 36 to 42 degrees. Flight 2 was carried out at 65 m and 70 m, with a radius of 75 m and 85 m and an inclination of 35 to 40 degrees. The third flight was flown at 55 m and 65 m, with a radius of 55 m and 70 m, and an inclination of 36 degrees. A total of 288 photos were acquired. Likewise, an additional manual flight was carried out to capture oblique shots every 3 seconds in the most exposed areas of the houses, through which 194 photos were acquired. The generated orthophoto had a resolution of 6 cm.

4.2 Expansion of the Urban Area

The expansion of the urban area was delimited directly from the images for the orthophotos produced for 2017 and 2023. Using ESRI ArcGIS 10.8 software, three polygon vector layers were created, one for each revised date. In the edition of layers, the urbanized areas were delimited, and modified surfaces were calculated for each of the dates. It should be noted that it was not possible to carry out this action for older images. This was because the low spatial resolution did not allow us to differentiate and identify, in detail, the urban and the rural limits. For this reason, the 2007 orthophoto was prepared by INEGI, which had a resolution of 50 cm per pixel.

4.3 Rainfall Series

Monthly rainfall information for the Teziutlán rain gauge from 1991 to 2022 was extracted from two databases of the National Water Commission. However, the information from the years 1995 and 2003 was incomplete.

5 Results

UAVs have been widely used, especially during the last decade, to analyze the diverse aspects of landslide disaster risk, especially those characterizing landslide hazards (Garnica-Peña and Alcántara-Ayala 2021). Following such an approach, it is possible to identify the expansion of the urban area of Juarez, Ávila Camacho, and Lindavista neighborhoods.

Although the original plan was to analyze a longer period, the quality of available images of the research area is not good enough to compare with information derived from the high-resolution images recently obtained using UAVs.

According to the analysis, the study area has a surface of 313,522 m2, of which one-third is currently built. The built area in 2007 was 98,906; a decade later, in 2017, it had only increased by 2,636 m2. However, in the following 5 years, it expanded to 7,537 m2 (Table 1).

Table 1 Expansion of the Urban Area
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Despite the lack of land-use planning implementation, the steep terrain greatly limits urban area expansion (Fig. 3). However, in some cases, this takes place vertically, increasing the load of the already landslide susceptible slopes.

Fig. 3
A photograph of multiple dwellings that vertically developed on the steep terrains.

Dwellings developed on landslide susceptible areas of Teziutlán municipality, Puebla, México

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The entire municipality has been developed without considering disaster risk management (Fig. 4). Even before the landslides of 1999, the occurrence of diverse disaster episodes called for the attention of regional and local authorities to consider incorporating the existing potential impact of hazards into policymaking

Fig. 4
4 aerial views exhibit the expansion of the urban area of the municipality of Teziutlan in 1956, the area of study in 1956, the municipality in 2017, and the area of study in 2017.

Images of the expansion of the urban area of the municipality of Teziutlán, Puebla, and the research area in 1956 and 2017

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However, the lack of coordination and accountability mechanisms at the subnational and national levels substantially limits progress in the municipalities and at-risk localities. Teziutlán has not been the exception. Efforts are heterogeneous regarding the local authorities’ particular interests.

Using the landslide inventory developed by Murillo-García and Alcántara-Ayala (2017), it is possible to identify the number of landslides in the area of interest. Accordingly, based on field observation and analyzing aerial photos and satellite images, 33 movements are recognized in an area of 17,649.9 m2. Likewise, 3 landslides are identified as occurring in 1942, one in 1974, and 27 during the disaster of October 1999 (Table 2).

Table 2 Temporal distribution of the number of landslides in the research area
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The consequences of the 1999 disaster were particularly severe, and temporarily enhanced the preoccupation of the inhabitants and Civil Protection authorities. In 2013, two additional landslides were induced by rainfall. Since no casualties were involved, this episode was not a strong reminder of the 1999 events and, most importantly, what can take place in the future (Table 2).

The spatial distribution of landslides in 2007 and their impact on inhabited dwellings are represented in Fig. 5. Now distinguishable is the development of houses on steep slopes, susceptible to landslides, expanding towards the bottom of the ravine.

Fig. 5
2 spatial distributions of landslides in 2007 highlight the expansion of the urban area, landslide, and study area. The locations such as Camacho, Lindavista, and Juarez are marked.

Expansion of the urban area and spatial distribution of landslides on the inhabited dwellings in 2007

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Figure 5 also shows the coalescence of two landslide deposits in the lower part of the ravine and their marginal impact on the community. Although a high percentage of the inhabited areas are not severely affected by the instability of the slopes, it is evident that some landslide crowns extend under the lower parts of the buildings. This has severe implications because of possible landslide reactivation.

There was little population growth over the next decade and limited urban encroachment (Fig. 7). This slower evolution could be linked to the development of housing areas in other areas of the municipal head booming over the 2007-2017 period.

However, the dwellings constructed in the Juárez neighborhood are developed in areas with active landslides. In the Ávila Camacho area, houses and landslides are encroaching on the bottom of the ravine (Fig. 6). In contrast, those in Lindavista continue to increase the load on the slopes with vertical constructions.

Fig. 6
A photograph of multiple houses that developed over a steep terrain.

Housing continues to be built, moving toward the bottom of the ravines, lacking proper drainage systems

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It is important to mention that at the community level, for example, the Juárez neighborhood possesses a well-functioning local committee that solves societal problems through their community efforts. Unfortunately, landslides are of concern in most places only when landslides have occurred in the recent past (Fig. 7).

Fig. 7
Two spatial distributions of landslides in 2007 indicate expansion of the urban area, landslide, and study area. The location such as Camacho, Lindavista, and Juarez, are marked.

Expansion of the urban area and spatial distribution of landslides on the inhabited dwellings in 2017

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The expansion of the urban area in Teziutlán has responded to the need to house people who immigrate from adjacent areas to work in the maquila, which is the main activity of the municipality. This leads to the creation of built landscapes of a mixed nature, in which the use of different materials with heterogeneous quality and resistance are used (Fig. 8).

Fig. 8
A photograph of several houses with mixed nature that are built over a steep terrain.

Built landscapes of a mixed nature have been constructed for immigrants who work for the maquila

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A larger area of urban development was identified in the analyzed image of 2023 (Fig. 9). Regardless of the previously recognized character of instability of the hillslopes, a vegetated slope in the Juárez neighborhood already affected by landslides is being transformed into an infrastructure zone. This involves the construction of three buildings, presumably for housing (Fig. 10). To a much lesser degree, small dwellings have been built in the north-eastern sector of the Linda vista neighborhood and the southwestern portion of Ávila Camacho (see Fig. 9).

Fig. 9
Two spatial distributions of landslides in 2023 indicate expansion of the urban area, landslide, and study area. The locations such as A. Camacho, Lindavista, and Juarez, are marked.

Expansion of the urban area and spatial distribution of landslides on the inhabited dwellings in 2023

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Fig. 10
An aerial photograph of several buildings in a highly susceptible area.

New buildings constructed in areas highly susceptible to landslides in the Juárez neighborhood, 2023

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Development of the urban space in Teziutlán takes place without considering territorial planning and even less integrated disaster risk management. While the collective memory of authorities regarding past disasters associated with rainfall-induced landslides are easily erased by economic interests and profits, community memory is often shaped by risk perceptions on which pressing issues concerning livelihoods, essential needs, and quotidian problems prevail over landslide disaster risk awareness and preparedness.

According to the available rainfall series, 2013, 2010, 1999, 2017, and 1949 recorded the maximum annual precipitation amounts in descending order. These corresponded to 2733.20, 2020.60, 1983.30, 1958.50, and 1949 mm of rain, respectively. The maximum monthly precipitation occurred in September in all years, and together with the precipitation of October, it amounted to 1146.50, 738, 942.5, 942.8, and 802.5 mm, correspondingly CONAGUA n.d.).

Indeed, rainfall threshold analysis requires more detailed and complete information. Nonetheless, from Fig. 11, it can be observed that the year 2013 was the wettest of the last three decades. After that year, no more landslides occurred. Thus, communities are inclined to neglect the understanding and remembrance of the causality of disasters they have suffered in the past. Therefore, it is suggested that beyond highly technical efforts to evaluate landslide disaster risk, a sound program of landslide disaster risk awareness should be put in place permanently to raise the consciousness of people at risk about the importance of working together and the necessity to avoid the construction of new risks.

Fig. 11
A stacked bar chart plots precipitation in millimeters for January to December from 1991 to 2022. The maximum precipitation occurred in the year 2013. The years 1995 and 2003 have incomplete information.

Monthly precipitation data at the Teziutlán, Puebla rain gauge, from 1991 to 2022 (Source: adapted from CONAGUA n.d.)

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6 Concluding Remarks

The skewed expansion of urban areas and the potential impacts of climate change (Adler et al. 2022) are among the most significant controls of landslide risk in Teziutlán, Puebla, México; a mountain zone highly susceptible to hillslope instability. This condition requires the significant involvement of authorities and communities in order to understand and address landslide disaster risk. The latter is strongly linked to the perception of risk.

Landslide disaster risk perception plays a key role, not only in terms of behavior, but as a basic element to improve community awareness and preparedness of authorities oriented toward disaster risk management (Landeros-Mugica et al. 2016). This goes hand-in-hand with risk communication as a process in which, starting from their original perceptions, it is possible to lead people to an adequate perception and to become aware of the risk involved.

Landslide disaster risk awareness requires significant efforts since it is closely related to people´s perception of risk. Consequently, it is important to design strategies to raise awareness and sustain such educational attempts over time.

Although exploratory in nature, the analysis carried out in the paper provides insights and recommendations to support landslide disaster risk awareness by suggesting future actions at the local level. A key recommendation is to implement a landslide disaster risk awareness program during the main festivities and traditional gatherings organized in the municipality. Likewise, education and religious institutions, along with places of work and transport, should incorporate spaces for information dissemination. There are several challenges attached to this type of initiative, including the difficulty of landslides occurring through time, in other words, not only during the rainfall season but throughout the year.

Likewise, programs and content should be directed to each population group, and when possible, they should include education programs at all levels. Finally, we recognize that only with this kind of radical effort can science and technology be intertwined with a solid commitment to the betterment of society (Alcántara-Ayala and Sassa 2021).