434 WEATHER, CLIMATE, AND SOCIETY VOLUME 6

Deaths by Lightning in (1979–2011): Threat or Vulnerability?

G. B. RAGA Centro de Ciencias de la Atmósfera, Universidad Nacional Autónoma de México, Ciudad Universitaria, México

M. G. DE LA PARRA Centro de Investigaciones y Estudios Superiores en Antropologı´a Social, Colonia Tlalpan, México

BEATA KUCIENSKA Centro de Ciencias de la Atmósfera, Universidad Nacional Autónoma de México, Ciudad Universitaria, México

(Manuscript received 2 August 2013, in final form 7 March 2014)

ABSTRACT

This paper presents evidence of the geographical distribution of deaths due to lightning over Mexico for the period 1979–2011. Over 7300 deaths occurred during this period, an average of 230 per year, which translates into an average fatality rate per million inhabitants of 2.72 (1979–2011). A total of 60% of the fatal victims occur in only 7 out of the 32 states in Mexico, with the largest fraction occurring in the state of Estado de México (24%). The largest death toll is found in the young male population, in rural regions of the states of Estado de México, Michoacán, and Oaxaca, where the population density is low. The results have indicated a clear bias in the fatal victims toward boys and young males (under the age of 25), with more than 45% of the total deaths in that segment of the population. While female deaths constitute a small fraction of the total number, the under-25 age segment also has the largest number of fatal victims. A county-level analysis of socioeconomic indicators clearly suggests that the geographical distribution of deaths is not correlated with population density nor with the maximum lightning density, but rather with vulnerability. The spatial distribution of deaths is better correlated with exposure to thunderstorms, agri- cultural activities, and low education levels. The large social vulnerability of those regions combined with the lack of recognition of the problem by society and the government are more likely responsible for the large death toll.

1. Introduction extrapolating from a death rate of 0.3 per million people in more developed countries, while other regions of the Lightning is one of the most spectacular weather world were assumed an annual fatality rate of 6 deaths phenomena and has fascinated people for centuries; per million (Holle 2008). While some countries keep de- several early societies associated the phenomenon with tailed records of deaths, others, particularly in the de- gods in their mythologies. But lightning constitutes a veloping countries, have less comprehensive reporting, very real threat to society in modern times, leading to as indicated by Cooper and Kadir (2010). severe injuries and death and should be considered se- Mexico is located in the tropics, with a marked rainy riously by the population. Holle and López (2003) and season where large cumulus clouds are prevalent. Holle (2008) have estimated that up to 24 000 deaths These clouds generate lightning affecting a large frac- occur globally due to lightning strikes, with an estimate tion of its territory (Christian et al. 2003; Kucienska et al. of 240 000 injuries. These numbers were determined 2010). The existence of a vulnerable population converts the natural lightning phenomenon into a serious risk Corresponding author address: Graciela B. Raga, Centro de (Wilches-Chaux 1993). It is necessary to explore the Ciencias de la Atmósfera, Universidad Nacional Autónoma de México, Circuito Exterior s/n, Ciudad Universitaria, Delegación vulnerability of the society and to understand how it Coyoacan, Mexico City DF 04510, México. may become a determining factor in leading to casual- E-mail: [email protected] ties. Another paradigm of the concept of disaster

DOI: 10.1175/WCAS-D-13-00049.1

Ó 2014 American Meteorological Society Unauthenticated | Downloaded 09/25/21 07:05 PM UTC OCTOBER 2014 R A G A E T A L . 435 develops around the lack of attention by government to state and county levels. It is worth noting that other small and moderate disasters, as opposed to huge di- studies (Lopez et al. 1993) have pointed out that there is sasters that may elicit international humanitarian re- a severe underreporting of lightning fatalities. This un- sponse. Small or moderate disasters have a slow impact derreporting may affect the statistical calculations and and occur at the local/county level. These are not per- introduce a bias for which it is very hard to correct. The ceived as disasters: they can accumulate over time and database used in this study is gathered from information become significant, but the government does not appear generated at hospitals and health care centers located prepared to take action to prevent these deaths. Mea- throughout the Mexican territory. sures such as the introduction of lightning injury pre- Additional information was obtained from official vention programs, as have been implemented in other census data in Mexico, taken by the National Institute countries, would seem logical to reduce the number of for Statistics and Geography (INEGI 2005, 2011a), for casualties. However, the study by Cooper and Kadir population and information on income, main activities, (2010) cautions that while it would be reasonable to ethnicity, education levels, etc., that help support the suggest measures that have been successful in reducing assessment of the level of vulnerability of the population. the number of deaths in more developed countries to Finally, we also use a lightning database recorded by developing ones, often the socioeconomic and social the World Wide Lightning Location Network (WWLLN) factors that separate the countries in such categories are that detects the very low-frequency radiation (‘‘sferics’’) the ones that lead to the large number of casualties in associated with lightning strokes. The network is cur- developing countries and are, thus, nonapplicable. rently formed by about 50 stations distributed around the The objectives of this study are (i) to analyze what world, located primarily at universities and research appears to be a fairly unique dataset of lightning casu- centers. WWLLN started operating in 2002 (Dowden alties in Mexico, collected by health care centers and et al. 2008) but only from 2005 onward did the detection hospitals throughout the country (not based on news- efficiency reach an acceptable level (Jacobson et al. paper reports) for the period 1979–2011; (ii) to relate the 2006; Abarca et al. 2010). Currently, the University of spatial patterns of the natural threat to the spatial dis- Washington coordinates the WWLLN network (http:// tribution of fatal victims; and (iii) to relate the fatal webflash.ess.washington.edu/indexnew.html). victims (by age, gender, ethnicity, and activities) to the Kucienska et al. (2010) evaluated data derived from patterns of social vulnerability in the country. In par- WWLLN, data from the optical transient detector ticular, we address whether the death toll is related to (OTD) located in the OrbView-1/MicroLab satellite the threat of the natural phenomenon or to the vulner- (Christian et al. 2003) launched in April 1995, and data ability of the population and to possibly evaluate the from the Lightning Imaging Sensor (LIS) located in role of government in reducing the number of injuries the Tropical Rainfall Measuring Mission (TRMM) sat- and fatalities due to lightning. ellite (Kummerow and Barnes 1998). From the com- parison of these datasets from OTD/LIS and WWLLN, Kucienska et al. (2010) concluded that the same annual 2. Datasets and analysis methodology variability was observed over Mexico and the four ad- The data analyzed in this study are part of a govern- jacent oceanic regions considered in the study. While the ment health database that contains the information on detection efficiency of WWLLN is still very low, the all deaths reported by hospitals and can be found online dataset is considered valid, since it displays the same (SINAIS 2010). While many studies have relied on sta- monthly variability as the 1995–2005 period of the OTD/ tistics based upon reports of lightning strokes in news- LIS dataset. papers (Gomes et al. 2006; Cooper and Kadir 2010), this study uses the official Mexican government database, 3. Results of the analysis of the fatalities database: which includes information from 1979 to 2011. Two vari- 1979–2011 ables of the database were considered: (i) lightning stroke a. Temporal evolution (code 907X) for the period 1979–97 and (ii) lightning stroke victim (code X33) for the period 1998–2011. It is A total of 7362 fatalities were reported in Mexico as important to mention that a change occurred in the re- ‘‘death by lightning stroke’’ during the period analyzed. porting methodology after 1998 that included more cat- Because of the changes introduced in reporting men- egories for deaths and more information on the victim. tioned in section 2, we divided the statistics into two The tables and graphs using this information were pro- periods, yielding 5458 deaths between 1979 and 1997 duced with the software DesInventar (La Red/CIESAS (19 years) and 1904 deaths between 1998 and 2011 (14 2010), allowing the analysis from the national level, to the years). These figures result in an average yearly death

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FIG. 1. Interannual variability of the density of fatal victims reported over Mexico for the period (1979–2011), per million inhabitants. Note the decrease shown from 1998 onward, when the Ministry of Health introduced changes in the reporting of fatalities.

rate of 287 (with a standard deviation of 43) for the period deaths by lightning time series of deaths appears mod- 1979–97, and a decrease to only 127 (with a standard erately correlated to the La Niña phase (correlation co- deviation of 54) in the more recent period. It is difficult to efficient 5 0.26). explain the large decrease observed in the more recent The annual distribution of fatalities is presented in years, since there were no measures introduced by the Fig. 2, indicating that the maximum in fatalities is ob- government in 1998 to try to diminish the large death toll served during July and August, with more than 1600 ca- observed between 1979 and 1997. The more relevant in- sualties per month reported for the whole period 1979– formation to discuss is the density of deaths per million 2011, in which a total of 7362 fatalities were reported. inhabitants as shown in Fig. 1. The population in Mexico June is third in the ranking of fatalities (1211), indicating has increased from 64 million in 1979 to 114 million in that the majority of the deaths occur during the first half 2011 (a linear increase was estimated from the infor- of the rainy season in Mexico (from June to October). mation reported in the official national census carried out Note that we have kept the separation between the two in 1970, 1980, 1990, 2000, and 2010). The first period in- segments because of the different reporting, and while dicates an average of 3.75 deaths per million inhabitants the total numbers have decreased in the more recent (with a standard deviation of 0.89), a value considerably period, they both exhibit similar annual variability. lower than the value of 6 deaths per million estimated by The study by Kucienska et al. (2010) constitutes the Holle (2008) as representative of the density of fatalities first published report of lightning activity over Mexico in the less developed countries. The average density of with 5 years of data from the WWLLN database (2006– fatalities in the second period decreases to 1.32 deaths per 09), presenting a preliminary climatology of lightning million (with a standard deviation of 0.50), but it is still over Mexico and adjacent oceans. The results from that over 4 times the value estimated by Holle (2008) for the study have been updated to produce the figures presented developed countries (0.3 deaths per million people). in this study. The monthly variability of lightning over the However, the last two years in the database (2010 and whole country indicates a maximum during August, fol- 2011) report densities of 0.59 and 0.67 per million people, lowed by September and July (Fig. 3). Very low activity is only about twice the value estimated for developed observed from January to March and in November and countries. Note that the density in both subperiods December, months that correspond to the dry season in shows a clear interannual variability, which could be the Mexico. While April and May show lightning density result of a number of factors, including variability in the comparable to October, little precipitation is observed lightning strikes due to changes in atmospheric con- during those months that corresponds to the transition ditions. Unfortunately, we are unable to compare the between the dry and wet seasons, and the high lightning- deaths by lightning with the physical phenomenon for to-precipitation ratio is perhaps linked to high atmospheric the whole period 1979–2011, since Mexico does not aerosol concentrations from the increased agricultural have a long record of measurements of cloud-to-ground practices (slash and burn) before the rainy season and also lightning strokes. The interannual variability of the industrial emissions (Kucienska et al. 2012).

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FIG. 2. Monthly variability of fatal victims reported for the whole period (dark gray bars) and for the two subsegments: 1979–97 (white bars) and 1998–2011 (light gray bars). b. Spatial distribution that the largest storms (in terms of areal and volume ex- tent and echo-top heights derived from the radar re- Figure 4 presents the spatial distribution of fatalities flectivity database) develop in the region of the central for Mexico, at the state level. As already noted, the total Mexican plateau and surrounding mountains (Novo and death toll in the period 1979–2011 is 7362, and only 7 Raga 2013). Michoacán has the second largest death toll of the 32 states account for 60% of all fatalities. The by lightning with a statewide population density of states with the largest number of fatalities are Estado 2 74 km 2. We will see that the majority of deaths in Estado de México (1777), Michoacán (721), Oaxaca (515), and de Mexico and Michoacán occur in this region of deep Guanajuato (406). The state of Estado de México is located convection, even though the counties are not very densely in the central plateau and Michoacán borders with it to populated. the west (both shown in brown in Fig. 4). The average The state of Oaxaca (shown in red in Fig. 4, popula- population density for Mexico as a country is only 57 tion density 5 41 km–2) is located on the southern Pacific inhabitants per square kilometer, but the different states coast and encompasses the Isthmus of Tehuantepec. vary widely in density. Estado de Mexico has the second 2 Large convective storms and systems are frequent in this largest population density at 659 km 2, because it sur- region during the rainy season, because of the northward rounds the federal capital (Mexico City, which has 2 movement of the intertropical convergence zone and a density of 5920 km 2). However, Estado de Mexico also includes many other less populated counties located away from the capital. As we will see later, the largest number of victims is not observed in the most populous counties that surround the capital, but rather in the rural areas in the western region of the state. The three other states with the largest numbers of fatalities in decreasing order have the following population densities: Michoacán, 2 2 2 74 km 2; Oaxaca, 41 km 2; and Guanajuato, 179 km 2 (see Fig. 4 to locate these states). The spatial distribution of lightning for Mexico (Fig. 5) identifies the location of the areas with the highest flash lightning density, showing a localized maximum in the southern part of the state of Veracruz, close to the southern region of the Gulf of Mexico. Two other re- gions of relative maxima are observed on the Pacific coast and in the southwest corner of the state of Estado FIG. 3. Average annual distribution of cloud-to-ground lightning de México (on the border of Michoacán and Guerrero). density in flashes per square kilometer per month over Mexico for This latter region is where a recent radar study has shown the period 2006–12.

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the south and similarly to the case of Oaxaca (population 2 density 5 41 km 2); there is no particular indication that the threat of lightning would be large in the region (see Fig. 5), suggesting that the large death toll may be related not to the actual threat but to other factors, and we postulate here that the factor that leads to the large fatality density is the vulnerability of the population. However, note that the total number of deaths by light- ning in Oaxaca and Guanajuato is only between one-third and one-fourth of the casualties reported in the state of Estado de México, which is the state with the second largest population density after Mexico City (with a very low fatality density). c. Social patterns: Age and gender FIG. 4. Spatial distribution of fatalities in Mexico between 1979 Figure 6 shows the number of fatalities as a function and 2011 reported by state. The boxes indicate the names of the four states with the largest number of fatal victims: Estado de of gender, keeping separate the two reporting periods Mexico, Michoacán, Oaxaca, and Guanajuato. mentioned in section 2. The number of female fatalities is small compared to the number of male fatalities, amounting to about only 21% of the total deaths for the tropical disturbances (e.g., easterly waves) that travel whole period analyzed. This smaller fraction of female through the region. Even though convection and pre- victims may be related to the type of outdoor activities cipitation are frequent in the region, the distribution of carried out by the different genders, as we will explore lightning (see Fig. 5) indicates only a very small region of and argue in section 4. the state bordering Veracruz with high lightning activity. Figure 7 shows the number of fatalities as a function of So, the natural threat is not very large and the population gender and age, again keeping separate the two periods density is lower than the national average, but this state, mentioned in section 2. There are a couple of notewor- one of the poorest in Mexico, has the third highest death thy points that emerge from these graphs. First, the toll by lightning. distributions are remarkably similar for both periods, In fourth place in terms of number of fatal victims is the but note that the vertical axes have very different scales, state of Guanajuato (shown in orange in Fig. 4, popula- so that in the more recent period (1998–2011) the 2 tion density 5 179 km 2), which borders Michoacán to maximum value is only about one-fourth of the older

FIG. 5. Average spatial distribution of cloud-to-ground lightning density in flashes per square kilometer per year for the period 2006–2012.

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FIG. 6. Interannual variability of fatalities as a function of gender. The two subsegments are indicated. period (1979–97). Second, the peaks of the distributions (roughly aligned east–west, where the highest volcanoes correspond to boys between 15 and 19 years old and girls in Mexico are located). These mountainous regions are between 10 and 14 years old for the period 1979–97. important in triggering deep convective storms, and While there is a slight increase in deaths of boys between during the rainy season there is a relative maximum of 10 and 14 in the more recent period (1998–2011), there lightning density located in the southwest corner of the is a marked shift toward older female fatalities, with state (see Fig. 5). a secondary peak observed for 20–24-year-olds. These The state of Estado de México is politically divided results indicate that a large fraction of fatal victims in into 125 counties (INEGI 2006), with a total population Mexico are boys between the ages of 10 and 19, with in 2005 of 14 007 495, divided into 6 832 822 males and about 45.8% of all male victims younger than 25 years 7 174 673 females (INEGI 2011b). About 76% of the old. Deaths in that age segment constitute 34.5% of all population is located in large urban areas, with 27% of fatalities (male and female). its population located in just 3 of the 125 counties, those that surround Mexico City. In terms of the education level of the population, 6% 4. Discussion has no formal education at all and 10% has not finished A natural phenomenon, like lightning, becomes a very elementary school. Only 27% of the population has serious risk when there is a vulnerable population completed middle school and only 15% has graduated (Wilches-Chaux 1993), which can then lead to a large from high school. These figures indicate the low levels death toll. It is necessary to explore the vulnerability of of formal education of the population of this state. the society and to determine how it may become a main Moreover, there is also a component of native pop- factor in leading to casualties. To evaluate the different ulation in the state, mainly from four ethnic groups: aspects that may define the social vulnerability, we will Mazahua, Otomí, Nahuatl, and Mixteca (about 250 000 concentrate on the state of Estado de México, which in total). While this number is small given the total accounts for the largest number of fatal victims (1777 population of the state, it is a fact that the native out of 7362). We will discuss physical geography, de- population has more difficulty accessing and complet- mographics, education level, and local economy to as- ing formal education and that they mostly inhabit rural sess social vulnerability. areas. The state of Estado de México (refer to Fig. 4), cen- Since the state surrounds Mexico City, most of the trally located in the country and surrounding the federal economic activities that contribute to the gross national capital (Mexico City), covers an area of 22 357 km2 and product (GNP) are related to manufacturing (28%) as mentioned before has the second largest population commerce (22%), and services (21%) (INEGI 2006). 2 density in the nation (659 km 2). Its topography consists While the statewide statistics only indicate that agri- of a high plateau (on average more than 1.5 km above culture contributes 1.3% to the GNP, it should be sea level) and partially includes two mountainous re- pointed out that agricultural activities for self- or local gions: the Sierra Madre del Sur (oriented roughly par- consumption are very widespread in rural areas and allel to the Pacific coast) and the transvolcanic axis would not appear as a quantifiable figure in the GNP.

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FIG. 7. Fatalities as a function of gender and age (5-yr intervals) for (top) 1979–97 and (bottom) 1998–2011.

We now concentrate on the counties where the largest largest 35 counties in the state listed in decreasing order fatality density is observed, those that are located in the of population. Note that the counties with the larger western part of the state. Table 1 presents a list with the populations are not necessarily those that report the 11 counties (out of 125 counties in the state) that are most fatalities. The entries in bold correspond to all the located from south to north along the western boundary counties listed in Table 1, where the percentage of area of the state. It is interesting to note that while agriculture dedicated to agriculture in each of them is shown. Note is only a marginal activity statewide (only 1.3% of the that most of those counties (highlighted in bold) have GNP), in these 11 counties, agriculture is the most a fatality density of more than 30 per million inhabitants important economic activity (INEGI 2006). The main per year, which is extremely large, more than an order of crops are maize, beans, chili, tomatoes, and squash, all magnitude of the average value for the whole country of which are staple foods of rural Mexico and clearly (2.72). In particular, the county for local or self-consumption, given the small areas is highlighted in bold and italics because even though it sown (Table 1). These crops require mainly unskilled has about one-seventh of the population of the largest manual labor (perhaps even involving children in the county (, where the state capital is located), it has fields) and depend on natural rains (not irrigated). In more than twice the number of fatalities in the period particular, note that the county San Felipe del Progreso 1979–2011; moreover, it reports the largest death rate has 70% of its surface devoted to agriculture. per million inhabitants per square kilometer (71) and on The link between total population per county and average, seven deaths per year in the period. This county deaths is explored through the data in Table 2, for the has 70% of its surface devoted to agriculture (Table 1)

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TABLE 1. Total surface, sown area (in 2009), and percentage TABLE 2. Population in 2005 (in decreasing order) and fatal sown for the counties located in the southwestern corner of the victims between 1979 and 2011 due to lightning in 35 counties (out state of Estado de México, from south to north. (Source: INEGI of 125) located on the western region of the state of Estado de 2011c) The county highlighted in bold and italics reports the largest México. Also listed are the estimates of density of deaths per mil- death rate per million inhabitants per square kilometer. lion inhabitants per year. The counties indicated in bold correspond to those listed in Table 1 and the county highlighted in bold and Total surface Area sown in Sown italics reports the largest death rate per million inhabitants per 2 2 County (km ) 2009 (km ) (%) square kilometer. 791 407 51.5 Deaths per 638 305 47.8 Population Total deaths million per Tejupilco y 1372 469 34.2 County in 2005 1979–2011 year (avg) 565 93 16.5 Otzoloapan 156 37 23.7 Toluca 747 512 110 4.5 Santo Tomas 104 36 34.6 Zinacantepec 136 167 38 8.5 100 26 26.0 Ixtlahuaca 126 505 60 14.4 Donato Guerra 191 88 46.1 Almoloya de Juárez 12 6163 56 13.4 Villa de Allende 308 190 61.7 San Felipe del Progreso 100 201 236 71.4 San Jose del Rincon 485 256 52.8 77 831 30 11.7 San Felipe del Progreso 366 258 70.5 77 819 100 38.9 Villa Victoria 422 203 48.1 77 714 48 18.7 Tejupilco y Luvianos 62 547 69 33.4 59 969 25 12.6 58 169 30 15.6 and is located in the west, but its location does not co- 56 849 37 19.7 incide exactly with the relative maximum in lightning Jocotitlán 55 403 8 4.4 density (located farther south). It appears that fatalities 52 902 25 14.3 are not strictly related to the magnitude of the threat but Villa de Allende 41 938 47 33.9 are also a result of the main activities (e.g., agriculture) 40 492 35 26.2 Tlatlaya 33 308 9 8.2 of the local population. Its population in 2005 was a little El Oro 31 847 17 16.2 over 100 000 but only 178 physicians in 35 medical cen- Temascaltepec 30 336 54 53.9 ters appear in the census for the county, which is in- Donato Guerra 29 621 27 27.6 dicative of low access to public health facilities for the Amatepec 27 026 27 30.3 rural population. Figure 8 shows that there is no corre- Morelos 26 430 13 14.9 24 986 29 35.2 lation between the natural threat (in terms of lightning 21 746 9 12.5 flashes) and the fatalities in the 35 counties listed in 20 343 28 41.7 Table 2. Texcaltitlán 15 824 8 15.3 One last aspect to be considered at the county level is 14 335 6 12.7 the one that links the low level of education of the Polotitlán 12 319 3 7.4 de Juárez 10 719 7 19.8 population with its increased vulnerability. Rural areas Santo Tomás 8888 4 13.6 have lower population but the education level is also Ixtapan del Oro 6349 13 62.1 lower, and it is there where the larger fraction of native San Simón de Guerrero 5408 6 33.6 population lives as well. The lower levels of education are Otzoloapan 4748 3 19.2 very likely related to the lack of knowledge about the 3836 3 23.7 physical phenomenon, its dangers, and the simple actions needed to be taken in cases of lightning threat. The population is also more susceptible to misinformation protection measures that is to blame for certainly a large about the phenomenon and, because of more traditional number of the fatalities (El Universal 2001). and religious beliefs, to relating it to supernatural aspects. Clearly, the loss of life associated with lightning is Newspaper articles that report deaths of youngsters and perceived by society at large and by the government adolescents recurrently mention the phrase ‘‘acts of as something that is beyond their power to prevent. God’’ and that ‘‘He gives life and He takes it.’’ Families However, in other countries the actions of paramedics that are affected by fatalities claim that ‘‘nobody should and first responders to a person struck by lightning are be blamed’’ for those deaths. But the newspapers often crucial to the victim’s survival. also report that the children took refuge under a large Other countries also carry out assessments of the tree when the storm started and that they were either damage to infrastructure and property as a result of playing soccer or working in the fields, actions most likely lightning strikes. In Canada, for example, while having related to their deaths. It is ignorance of the basic a very low fatality density, the government estimates

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million inhabitants occur in mostly rural regions with low education levels and low access to medical facilities and mostly affect children and adolescents.

5. Conclusions Cloud-to-ground lightning constitutes a real natural threat to populations everywhere and in particular in Mexico during the wet season (June–October). This study presents the first evidence of the relationships between the spatiotemporal distribution of the phe- nomenon and fatalities due to lightning strikes. While there are regions where the natural lightning threat is clearly larger than in other regions, the fatalities are not necessarily related to the threat but also appear to be FIG. 8. Dispersion diagram of fatalities (1979–2011) as a function of the result of a combination of factors. In fact, the flashes per year in the counties listed in Table 2. largest lightning density is observed in the southeastern portion of the country and there are very few fatalities losses of about CAD $0.6 billion–$1 billion (Mills et al. reported there. 2010). Unfortunately, there are no equivalent data of More than 7300 people died by lightning stroke in the economic losses gathered in Mexico for comparison. period 1979–2011 in the country, resulting in an average However, since the largest fatality densities are found yearly death rate of 287 6 43 for the period 1979–97, and in rural areas with low population density, if the data on a decrease to only 127 6 54 in the more recent period economic losses were available, then it would likely be (1998–2011). Considering the population growth in the small, given that the large fatality rates are observed in country, the first period results in an average of 3.75 rural counties, where subsistence agriculture is the main deaths per million inhabitants (with a standard deviation activity. of 0.89), a value considerably lower than the value of 6 Finally, it is clear that the loss of these young people deaths per million estimated by Holle (2008) as repre- over the years is not seen as a disaster to society. The sentative of the density of fatalities in the less developed lack of attention paid by the government to small and countries. The average density of fatalities in the second moderate disasters as opposed to a huge disaster (e.g., period decreases to 1.32 deaths per million (with a earthquake), may also play a role in the large number of standard deviation of 0.50), but it is still over 4 times the fatalities, particularly in rural areas. Small or moderate value estimated by Holle (2008) for the developed disasters have a slow impact and occur at the local/ countries (0.3 deaths per million people). The last 2 years county level. These deaths are not perceived as disasters, in the database (2010 and 2011) report densities of 0.59 but they can accumulate over time and become signifi- and 0.67 per million people, only about twice the value cant. Some of the statistics of deaths presented for the estimated for developed countries. counties in the southwestern portion of the state of A total of 60% of the fatal victims occur in only 7 out Estado de Mexico indicate that there are indeed ex- of the 32 states in Mexico, with the largest fraction oc- tremely large fatality densities per million inhabitants and curring in the state of Estado de México (24%). Within that they are related to the vulnerability of the population. this state, the fatal victims are primarily found in cer- However, it seems that because the population considers tain counties (not the ones with the largest populations the deaths to be related to supernatural forces, it does densities, which are located surrounding Mexico City), not demand that the government take action to prevent mainly located in the western and southwestern portions them. The majority of the population in Mexico lives in of the state, where the dominant agricultural activities major urban centers, and hence, there has been a decrease may be exposing the population to the natural threat. in the individual risk exposure. However, we have shown Moreover, those counties have less than 15% of the state that the large death toll in Mexico is related to agricultural population, have more native population with a low activities and large fatality densities are seen in rural formal education level, and have a fatality density over counties,withmorethanhalf(andupto70%)oftheir an order of magnitude higher than the national average. area dedicated to agriculture, implying that the pop- The results have indicated a clear bias in the fatal ulation working in the fields would be very exposed to the victims toward boys and young males (under the age of natural threat. Moreover, the largest fatality densities per 25), with more than 45% of the total deaths in that

Unauthenticated | Downloaded 09/25/21 07:05 PM UTC OCTOBER 2014 R A G A E T A L . 443 segment of the population. While female deaths con- data monitoring and constant improvement of the re- stitute a small fraction of the total number, the under- trieval algorithm. This study was partially funded by 25 age segment also has the largest number of fatal Projects SEP-Conacyt 62071 and 154729 and Semarnat- victims. Conacyt 23499. Socioeconomic activities at the county level in the counties that report the largest numbers of fatal victims REFERENCES suggest that the vulnerability of the population stems from low educational levels and from performing agri- Abarca, S., K. Corbosiero, and T. J. Galarneau Jr., 2010: An cultural activities outdoors, which increase their expo- evaluation of the World Wide Lightning Network (WWLLN) using the National Lightning Detection Network (NLDN) as sure to the phenomenon (mainly during the first half of ground truth. J. Geophys. 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