A new data set of landslides that caused loss of life in Latin America and the Caribbean in the 10-year period from 2004 and 2013 inclusive has been compiled, providing new insight into the impact of landslides in this key part of the world. This data set indicates that in the 10-year period a total of 11 631 people lost their lives across the region in 611 landslides. The geographical distribution of the landslides is highly heterogeneous, with areas of high incidence in parts of the Caribbean (most notably Haiti), Central America, Colombia, and southeast Brazil. There is significant interannual variation in the number of landslides, with the El Niño/La Niña cycle emerging as a key control. Our analysis suggests that on a continental scale the mapped factors that best explain the observed distribution are topography, annual precipitation and population density. On a national basis we have compared the occurrence of fatality-inducing landslide occurrence with the production of locally authored research articles, demonstrating that there is a landslide research deficit in Latin America and the Caribbean. Understanding better the mechanisms, distribution causes and triggers of landslides in Latin America and the Caribbean must be an essential first step towards managing the hazard.
Landslides are a ubiquitous hazard, mainly occurring in high relief areas of the world, and they represent a significant source of loss of life in such terrains. Regions such as South Asia and South America are characterised by high tectonic uplift rates, which lead to steep, unstable slopes; and populations that are often concentrated in deep valleys prone to catastrophic landslides. Thus, the background landslide risk is comparatively high. It is widely considered that landslide vulnerability in mountain environments is further increased in areas of dense urbanization and/or where precarious squatter settlements have developed on, or at the foot of, steep slopes in poor or developing countries (Alexander, 2005), as is the case of large Latin American cities such as Rio de Janeiro, Caracas and Valparaiso.
The acquisition and analysis of historic data of casualties due to landslide events is key for the evaluation of risk. Most examples are found on a national level (e.g. Evans, 1997; Guzzetti, 2000; Guzzetti et al., 2005; Salvati et al., 2010). Only in the last decade a more systematic generation and analysis of landslide catalogs at global to continental scale have been developed, such as those of Nadim et al. (2006), oriented to hazard and risk analysis at a global scale, or Kirschbaum et al. (2010, 2015) who produce and analyse a global catalog for rainfall-induced landslides. Van Den Eeckhaut and Hervás (2012) present and analyse a number of national landslide databases for Europe.
On a global basis, Petley (2012a, b) compiled a database of landslides that caused loss of life for the period 2004 to 2010, demonstrating that losses were considerably higher than had been previously considered. In the latter studies, a number of hotspots of landslide activity were identified, most notably in parts of China, South Asia, Southeast Asia, the Caribbean, Central America and South America. However, detailed analysis of each of these areas was not undertaken. A disadvantage with the original study was that most of the data acquisition was undertaken using English language textual searches. Petley (2012b) noted that this might cause an under-sampling in those areas with low penetration of English, noting that this problem might be particularly serious in, for example, Latin America.
This study seeks to describe, quantify and understand the distribution of landslides that cause loss of life in the Caribbean and Latin America. In doing so, this study extends the database of Petley (2012a, b) using search terms in local languages (most notably Spanish) and by including a longer time period (10 rather 7 years). Thus, it seeks to provide the first comprehensive decadal-scale understanding of the spatial and temporal distribution of landslide losses in this key region of the earth.
Data on the occurrence of landslides that resulted in loss of life worldwide have been collated since September 2002 in the Durham Fatal Landslide Database (DFLD). The methodology through which the data are collected was described in detail in Petley et al. (2005, 2010), and analyses of the data set through to the end of 2010 are presented in Petley (2012a, b). The data set has also been used for analyses of specific aspects of landslide impacts, such as the relationship with climate in South Asia (Petley et al., 2010) and the occurrence of fatality-inducing landslides associated with large dams (Petley, 2013).
In brief, the data set is compiled through a combination of a daily internet search with pre-determined keywords, plus the use of the research literature; government and aid agency reports; and in some cases direct correspondence. The data set includes all mass movements, including landslips, debris flows and rockfalls, but snow and ice avalanches, and hyperconcentrated flows are excluded. The data set includes anthropogenically induced landslides.
The location of each landslide is identified using a range of tools,
primarily the National Geospatial Intelligence Agency's Geonames Search
Engine (
The reliability of the data set is described in Petley et al. (2005) and
Petley (2012a). In general the data set probably slightly underestimates the
occurrence of fatality-inducing landslides for two key reasons:
The data set inevitably fails to capture some smaller events, especially
in remote mountainous areas. However, it is likely that such events represent
a small proportion of the total number of fatalities; The data set probably fails to register all of the deaths associated with
some larger landslide events, most notably those victims who succumb to
injuries after being recovered from the landslide.
In common with other natural hazard impact data sets, the greatest errors in terms of losses are likely to occur in the largest events, when it can be difficult to determine reliably the total losses. This can be particularly pertinent in the case of very large landslides in poor countries in which the recovery of bodies is generally not practicable, and the ability to ascertain exactly who has been killed is limited.
In this study, an entirely separate attempt was made to compile a landslide
fatality data set for South and Central America, and the Caribbean. In this
case the search used key terms in Spanish, such as
Number of fatal landslides and fatalities for each country with positive cases.
We have examined the EDFLD in the context of a range of physical and social
data sets as follows:
Topographic parameters such as slope gradient, obtained from the Shuttle
Radar Topography Mission with 30 m resolution (SRTM30). Regional geology, obtained from the Geological Map of the World
(CGMW, 2010). Rainfall data, acquired from the Global Precipitation
Climatology Center (GPCC) 1 Regional seismicity, characterized using the data from the
Global Seismic Hazard Map Project (GSHAP; Giardini et al., 1999, 2003). National population and development data, obtained from the
United Nations 2012 World Population Prospects (United Nations, 2013) and the
2013 Human Development Report (UNDP, 2013). The country corruption factor, which has been identified with a
strong positive correlation with casualties during earthquakes (Ambraseys and
Bilham, 2001; Escaleras et al., 2007), obtained from Transparency
International Corruption Perceptions Index (Transparency International,
2013). The spatial population density for the year 2000, mapped by the
NASA Earth Observatory based on data from the Socioeconomic Data and
Applications Center (SEDAC) of Columbia University (NEO, 2014). Whilst data
from 2000 are now somewhat out of date, it probably remains the most
comprehensive data set of this type available.
This work is aimed at a continental scale. We neither attribute slope angles or other parameters to single landslides, nor map the landslides in detail, just their location. The used data sets, including a 30 m resolution DEM (Digital elevation model), allows analysis of the landslide distribution at this working regional scale, with all the uncertainties that it implies. We do not attempt to carry out any specific analysis at local scale or for individual landslides, which would be a different type of study.
The EDFLD recorded in Latin America and the Caribbean a total of 611 landslides causing 11 631 deaths in the 10-year period between 2004 and 2013 inclusive (Fig. 1 and Table 1). Fatal landslides were recorded in 25 countries (seven in Central America, nine in South America and seven in the Caribbean; Fig. 2 and Table 1). The year with the most fatal landslide events was 2010 (133 cases) while the lowest number was registered in 2004 (21). Other years with high landslide activity were 2005, 2008, 2009 and 2011 (Fig. 1). While the number of cases is mainly dominated by small landslides with a few casualties, the annual number of fatalities is strongly influenced by a low number of catastrophic events (Fig. 1). Thus, the year with the highest recorded number of deaths caused by landslides was 2004 (3865), which is also the year with smallest number of fatal events. This total was controlled by a landslide disaster in September 2004 triggered by Hurricane Jeanne in Haiti, causing over 3000 casualties. Other years with high fatality records are 2005 (2076 deaths, over half of them from a single large event in Guatemala), 2008 (1199 fatalities, almost half of them from another hurricane-induced event in Haiti), 2010 (1277 fatalities) and 2011 (1688 records), the latter two heavily influenced by multiple rainfall-induced landslides in Brazil.
Number of
Nearly 90 % of the recorded cases in the EDFLD were triggered by heavy
rainfall, from which 15 % were clearly identified as related to a
hurricane or tropical storm episodes (Fig. 3), mainly in Central America and
the Caribbean. Only 4 % of the cases were induced by earthquakes, with
the remainder being associated with construction, mining or volcanic
activity. In terms of fatalities it is remarkable to note that the
hurricane-related cases represent over 50 % of the deaths (Fig. 3), and
even this might be undersampled as in such events landslide deaths are often
not identified as such. Nevertheless, it is important to note that in the 10-year study period there were no cases in the study area of extremely large
(i.e.
Location of fatal landslides in Latin America and the Caribbean (black dots) in the period 2004–2013 according to the EDFLD.
The frequency distribution of the annual data as well as the whole data set show a strong inter-annual consistency (Fig. 4), although for events with more than a few hundred fatalities there are no records for many years. There is a slight reduction in gradient of the frequency curve for events with a small number of deaths, which has also been identified for the global database (Petley, 2012a). This is probably due to under-sampling of small cases, especially from some countries where the number of records is surprisingly low or even null (for example Bolivia and Cuba, respectively). However, there is no consistent rollover for the smallest landslide events in the fatality data, as is found for some landslide volume and area (Malamud et al., 2004) data sets.
Main triggers of fatal landslides in the studied period.
The annual total data show high levels of inter-annual variability in the temporal distribution of events (Fig. 1). However, the annual patterns suggest some seasonality, which is unsurprising given that most of the cases are related to climatic conditions (Fig. 5). In terms of the number of landslide events, peaks occur early in the year and in the September–November period, with the highest peak in early October. The fatality record generally coincides with this, but the influence of single catastrophic events generates a much noisier data set.
Annual and total probability density functions of fatal landslides for Latin America and the Caribbean.
Annual cycle of fatal landslides and fatalities shown in 5-day bins (pentads).
This seasonality in the number of fatal landslides has a strong correlation with precipitation patterns at a sub-continental scale, as is the case for Asia (Petley, 2010). The annual precipitation cycle differs between regions, and the landslide record tends to follow these changes (Fig. 6). While in Central America and the Caribbean the hurricane season, mainly between September and November, controls the landslide temporal distribution, in South America it is large storms in November–January and March-April that have a strong influence, especially in moist countries such as Brazil and Colombia, and to a lesser extent in the arid Andean highlands of southern Peru, Bolivia and northern Chile, where summer and/or early autumnal rain periods are the main trigger of landslides and debris flows (e.g. O'Hare and Rivas, 2005; Carreño et al., 2006; Sepúlveda et al., 2014). The clear positive correlation between the number of fatal landslides per month and monthly precipitation data for each region (Fig. 6d) show that the number of events is higher in Central America for moderate to low precipitation, while for the largest rainfall amounts tend to produce more cases in South America.
The countries with the highest number of fatal landslides in the studied period are (in decreasing order) Brazil, Colombia, Mexico, Guatemala, Peru and Haiti. The same six countries record the largest amount of fatalities, in this case led by Haiti (Table 1). The seasonal variations discussed above are mainly controlled by landslide activity in these countries.
Monthly distribution of landslides in 2004–2013 and mean monthly
precipitation in the same period (GPCC 1
Spatial distribution of landslides (black dots) on top of
The spatial distribution of landslides causing loss of life may be controlled by both natural and human factors, and may vary strongly even within a country. We have undertaken a first order, coarse-scale analysis of the relationship between a series of natural and social conditioning factors and the landslides in the EDFLD. For this first-order analysis, we use slope gradient to account for relief and regional lithology to illustrate the natural controlling factors at the macro-scale (Fig. 7). As expected, landslides tend to occur in regions with high topographic gradients, such as the Andean range in South America and hilly zones in Central America and the Caribbean. However, some gaps can be observed, for example in the eastern slope of the Altiplano plateau in Bolivia and northern Argentina, and in northern Mexico, illustrating that topographic factors do not solely account for the landslide distribution. The regional lithology factor (Fig. 7) is even less clear, although it can be observed that most landslides occur in regions dominated by igneous and metamorphic rocks, which tend to coincide with higher slopes. However, at a local scale, the geology is likely to be a key factor determining the occurrence of landslides. Because of the coarse-scale of our study and of the data used here, no further analysis was undertaken on this factor.
As commented before, most of the landslides of the database were triggered by
heavy rainfall, and to a lesser extent by earthquakes. Figure 8 shows the fatal
landslide distribution in comparison with regional seismicity, represented by
the GSHAP seismic hazard map by Giardini et al. (1999, 2003) and mean
precipitation in the studied period (GPCC, Schneider et al., 2011a). Given
the tectonic setting, the Andean range in western South America as well as
Central America and the Caribbean islands are seismically very active,
showing a good coincidence with landslide locations. However, given that
As the data set is focused on fatalities, social factors are also likely to influence the spatial distribution of fatal landslides. Areas where natural conditioning and triggering factors are favourable for landsliding, but which have only small populations, would not be likely to generate many fatal events. At the country level there is a strong correlation between numbers of fatal landslides and the national population, and an even stronger correlation with population density (Fig. 9). The more densely populated areas in hilly terrain, such as in central Colombia, SE Brazil and some Caribbean islands, generate more fatal events, illustrating that higher exposure and vulnerability increase the chances of fatal landslide occurrence. At a national scale, population density (Table 2) has a strong positive correlation with landslide density (Fig. 9).
Population data (United Nations, 2013) and scientific research on landslides indices (ISI Web of Science) for those countries with fatal landslides during 2004–2010.
As discussed by Alexander (2005), the location of dense populations in precarious, informal or poor urban settlements in less developed countries is a critical factor in determining high numbers of fatalities in landslide events. An analysis of settlement type, based on the EDFLD data, indicates that while only 41 % of the fatal landslide events were recognized in poor or informal settlements, 81 % of the fatalities occurred in such locations. We have also examined the relationship of total fatalities per country during the studied period with other socio-economic factors (Supplement 1), such as Gross National Income and the Human Development Index (UNDP, 2013). A weak increasing trend of fatalities induced by landslides can be observed for less developed countries, but the scatter is much higher than for population density. A similar tendency is obtained when the number of fatalities is compared with an indication of the level of corruption in each country using the Country Corruption Perceptions Index (Transparency International, 2013). Once again this shows a positive trend (i.e. that more corrupt countries tend to have more recorded landslides) but the level of scatter is high, possibly due to the complexity of the landslide phenomena that cannot be directly related to single societal indexes such as these at this scale.
These analyses indicate that the best representation of the spatial distribution of observed landslides at a regional scale for the study area is derived from slope gradient, precipitation and population density maps, as noted by Parker (2010) on a global scale for the original DFLD. Combinations of these factors improve the relationships further. For example, the direct product of slope and mean annual precipitation generates a good fit to the data, which is improved further when population density is included (Fig. 10). Thus, these three factors should be considered as first order controlling factors of fatality-inducing landslides in the study region.
Combined maps of:
As noted by Petley (2012b) with examples in Hong Kong and China, research can play a key role in reducing the impact of natural hazards, especially if the knowledge is properly transferred to national and regional agencies in charge of civil protection, urban planning and emergency response. Petley (2012b) showed that for landslides at a global scale, the volume of research (as indicated by the number of published peer-reviewed articles) has increased substantially in the last two decades, but that this development is geographically heterogeneous. He showed that those countries with the highest levels of research (i.e. with the highest number of landslide articles) generally have lower number of fatalities. Note that the relationship is complex, with levels of research also indicating levels of wider societal investment (in, for example, infrastructure, emergency response and hazard management), which may also reduce landslide losses. In terms of research however, whilst knowledge obtained from one location may be transferable to another, there are many impediments to transfer such knowledge to less developed countries, including the small number of local researchers, a lack of funding and language differences (Petley, 2012b).
In this study we have undertaken a similar but more detailed analysis for Latin America and the Caribbean. Research papers with landslide or landslides in the title, abstract or keywords published in the 2004–2013 period were searched in all databases available in the Thomson Reuters ISI Web of Science database (including the Web of Science Core Collection, Scielo and others) for every country with records of fatal landslides in the same period (Table 2). The records were searched by country, using the institutional address of at least one of the authors as a national indicator. A total of 354 academic papers were recorded in the period, from which 62 % are from South America, 30 % from Central America and 8 % from Caribbean countries. In common with the global data set, there is a notable increase (more than double) in the last decade in the number of academic papers published on landslides in the study area (Fig. 11). This increase is strongly driven by the South American countries, and may well have helped to keep the fatalities trend relatively stable despite the increase in population.
The country with most academic papers with at least one local author in the study time period is Mexico with 76 publications, followed by Brazil (69), Argentina (41), Chile (36) and Colombia (29). Figure 12 illustrates the relationship between the number of scientific publications on landslides and the number of fatalities, considering those countries with more than 10 fatalities in the 10-year period. While it is evident that some countries, such as Haiti and Guatemala, have large numbers of fatalities with very little research, for big countries such as Brazil and Mexico the number of casualties is still high even though they are the leaders in scientific publications (Fig. 12). However, the huge differences in national population in the region (Table 2) should be accounted for a more refined analysis. If the number of academic papers and fatalities are both normalized by total national population, clearer patterns can be identified (Fig. 12), with a higher rate of fatalities caused by landslides in countries with lower normalized scientific production. The most productive countries in terms of research papers per capita, with over one paper per million people in 10 years, are Costa Rica (3.2), Trinidad and Tobago (2.3), Chile (2.1), Jamaica (1.8) and Ecuador (1.1). It is interesting to note that of those only Chile and Ecuador have more than 10 million inhabitants, with other medium- and big-size countries presenting lower rates of scientific production per capita. Nonetheless, those levels of research are still far from landslide-prone, developed countries, where the same indicator reaches values as high as 40.9 (Norway) or 21.5 (Italy). With better science policies and improved funding schemes, Latin American and Caribbean countries may start to approach countries such as United States (4.3) or Japan (4.6).
Scientific papers on landslides (Web of Science databases) annual distribution of all countries with recorded fatal landslides.
At the coarse scale the spatial incidence of fatality-inducing landslides in Latin America and the Caribbean is primarily the result of a combination of high relief, dense populations and energetic trigger events (over the time period in question, primarily precipitation). Thus, populated, humid upland regions of Brazil, Colombia, Haiti or Guatemala represent zones of high landslide occurrence resulting in loss of life. The role of precipitation is emphasized at the subcontinent scale, where a seasonal pattern is clear in the annual data that reflect the local precipitation cycle (which varies across the region). The mortality rate is higher in less developed countries that undertake little scientific research.
The original data set in English included about 95 % of the total identified fatal landslide cases, showing that coverage in English is reasonably, and perhaps surprisingly, good for this sort of study. It is not clear if this would remain for non-fatal cases that are not frequently covered by the media. The use of Spanish terms to enhance the data set was of limited value, adding generally small events with few casualties and often in small countries, such as Ecuador, that might not have as good coverage by global media in English as others. Nevertheless, the search in Spanish was not done systematically during the whole studied period as in English, but was performed at the end of the period, with a higher number of cases for the last 3 or 4 years, possibly due to the deletion of older web pages. This factor, along with the absence of other important languages spoken in the continent such as Portuguese, may have precluded an optimum coverage of all cases.
For much of Latin America, rainfall events are positively affected by strong El Niño events, especially in southern Andean countries (e.g. Moreiras, 2005; Sepúlveda et al., 2006), while for Colombia an increase of landslide activity has been observed during La Niña periods (Klimes and Ríos-Escobar, 2010). The 1996–1997 El Niño event, the strongest on record to date, was associated with heavy rainfall and large numbers of landslides in the study region. The period of this study coincides with a phase of the El Niño Southern Oscillation (ENSO) in the Pacific (Trenberth, 1997) that has favoured comparatively weak El Niño and strong La Niña events, such that during the study period, no large El Niño events occurred. However, early 2010, which was characterized by moderate El Niño conditions, also represents the peak occurrence of fatal landslides in our study, while a weak correlation between La Niña conditions and higher landslide activity can be observed in Colombia and Venezuela, in particular for late 2010–2011.
Thus, the spatial and temporal patterns presented here represent those associated primarily with moderate to strong La Niña periods. It is likely that the spatial and temporal patterns of fatality-inducing landslides will be different during a strong El Niño event. Thus, at present the EDFLD will not properly represent the long-term occurrence of fatality-inducing landslides in the Caribbean and Latin America until such an event is captured. In fact, a study of a smaller data set between 1993 and 2002 reported by Alexander (2005) returned Venezuela, Nicaragua, Colombia, Haiti and El Salvador as the Latin American or Caribbean countries with more deaths caused by landslides, showing that there is only partial coincidence with our data set from 1 decade later.
The occurrence of a rare but extreme landslide event, such as the 1970 Huascaran rock avalanche (Evans et al., 2009) or the 1999 Vargas debris flows (Bezada, 2009), may multiply the number of casualties by an order of magnitude or more, making it difficult to extrapolate our results to the long term. As shown by Guzzetti (2000), the average number of fatalities per year is extremely variable, but higher in active regions such as the Andes, which is consistent with our results.
A perhaps surprising finding is that during the study period earthquakes
triggered only small numbers of fatality-inducing landslides. Latin America
and the Caribbean are known to be prone to seismically induced landslides
(e.g. Bommer and Rodriguez, 2002; Schuster et al., 2002) because of the
combination of high rates of tectonic activity and steep slopes. The study
period captured the largest earthquake in the region in about 40 years (the
2010 Mw
The lack of recorded fatalities from seismically-induced landslides should not be taken to infer that this issue is no longer a problem in Latin America and the Caribbean. Instead, it is the consequence of a paucity of large, shallow earthquakes affecting vulnerable populated areas with steep slopes during the study period. It is likely that the next large earthquake of this type in Latin America and the Caribbean will induce large numbers of fatality-inducing landslides.
In a previous assessment as part of the World Bank hotspots analysis of natural disasters, Nadim et al. (2006) produced a global-scale landslide hazard and mortality risk map. The EDFLD data set can be considered to be the realisation of landslide mortality risk over the study period. Whilst in some areas, for example in the Andes and in Central America, there is a good relationship between the landslide and mortality risk maps, in other areas (such as Brazil) the World Bank analysis strongly underestimates mortality risk. The probable reason for this is that in the World Bank approach hazard is assessed by multiplying a number of factors, including precipitation and seismic hazard. Thus, in an area of low seismic hazard, such as Brazil, it tends to generate a comparatively low hazard (and thus risk) score, which therefore fails to capture adequately the true risk in these areas.
However, we also note that the lack of large landslide-inducing seismic events also means that there is no mechanism to benchmark properly the risk from earthquake-induced landslides in Latin America and the Caribbean. This will need further attention in due course.
Even though no simple and direct link between research and landslide impact can be concluded, as other factors such as research quality and lag times or incapacity to apply research results in disaster prevention should be considered – as well as other important processes including education – our analysis reinforces the idea that research can play a significant role in reducing the loss of life from landslides. Future work should explore in depth what factors or research and its communication (e.g. type of study, type of publication) may have a stronger impact in disaster prevention. It also should take into account the potential impact of unpublished reports, usually issued by national geological services or emergency offices, or articles in local congress proceedings, as local scientists outside the academic system in this region do not always publish in journals.
This study has evaluated the occurrence of fatality-inducing landslides in Latin America and the Caribbean in the period 2004–2013 inclusive. Over this time period we recorded 611 landslides that caused 11 631 deaths, mostly as a result of rainfall triggers. The geographic distribution of the landslides is heterogeneous, but mostly reflects the combination of relief, precipitation and population density. In urban areas, the presence of informal settlements has a big impact on the number of fatalities, showing the effect of poverty and marginalization.
For the different parts of the study region the occurrence of landslides reflects the annual precipitation. In the longer term the data set has not captured a strong El Niño event or a series of large earthquakes in landslide-prone areas. It is likely that the long-term spatial and temporal patterns would be changed when such events are captured properly.
The study also shows that there is a research deficit in terms of landslides in the study area. Increasing understanding of landslides in these regions is likely to be a pre-requisite if a meaningful reduction in landslide losses is to be achieved.
The authors acknowledge the support of the Durham International Fellowships for Research and Enterprise (DIFeREns, cofunded by Durham University and the European Union), for funding a research stay of Dr. Sepulveda at the Institute of Hazard, Risk and Resilience of Durham University. Marisol Lara, Paulina Arellano and Constanza Celis aided with the completion of the database from Spanish-spoken sources and events classification. We thank S. T. McColl and an anonymous referee for their valuable comments and suggestions on the manuscript. This research was enabled by the NERC/ESRC Increasing Resilience to Natural Hazards programme under the Earthquakes Without Frontiers project, grant reference NE/J01995X/1, NERC/Newton Fund grant NE/N000315 and Fondecyt 1140317 project. Edited by: P. Tarolli Reviewed by: S. T. McColl and one anonymous referee