1. Assessing the Volcanic Threat of Central American Volcanoes
José Luis Palma, William Rose and Rüdiger Escobar-Wolf
Department of Geological Engineering and Sciences
Michigan Technological University

2. Outline Introduction to Central American volcanoes
Calculation of Hazard, Exposure and Threat scores
Results and comparison with some well known U.S. Volcanoes
Discussion on Vulnerability
Conclusions

3. Introduction
Central America is one the most volcanically active regions of the world. Through Guatemala, El Salvador, Honduras, Nicaragua, Costa Rica and Panama, there are 80 Holocene volcanic centers of which 27 have exhibited historic activity.

4. Map of Volcanoes in Central America
This map shows all volcanoes active in the Holocene (white triangles) and historically (green triangles).
The colors in the map represent the logarithm of the population obtained from the LandScan database (LandScan 2007).
Only the names of the 24 most active and best documented volcanoes are shown (were studied).
Some of these volcanoes are immediately adjacent to large cities with several thousand inhabitants. A striking example is San Salvador volcano, in El Salvador, with more than 500,000 people living within 10 km from its summit.
(Capitals: Guatemala city, San Salvador, Managua, San Jose de Costa Rica… Tepucigalpa in Honduras and Panama in Panama)

5. Quantifying Volcanic Threat
The volcanic threat is quantified using the ranking system developed by Ewert et al. (2005, 2007) as part of the Framework for a National Volcano Early Warning System in the United States.
Ewert et al An Assessment of Volcanic Threat and Monitoring Capabilities in the United States: Framework for a National Volcano Early Warning System.USGS open-file report
Ewert System for Ranking Relative Threats of U.S. Volcanoes. Natural Hazards Review v.8 p

6. Quantifying Volcanic Threat
The way it works is that you have to compile relevant information about the hazards and exposure to those hazards for each volcano. Most of this info was obtained from the Smithsonian web site + papers
Past Eruptions: includes factors related to the type of volcano, VEI of eruptions within the past 500 and 5000 years, and recurrence interval of eruptions
Holocene flows: occurrence pyroclastic flows, lava flows that reached populated areas, lahars and tsunamis in the Holocene.
Potential Hazards: includes information about potential sector collapses, hydrothermal explosions and source of permanent water/ice on the edifice.
Historical unrest: it considers observations of volcano seismicity, ground deformation and evidence of magma degassing
Ground-based population: Log10(VPI_30km), Log10(pop downstream) and whether it constitutes a significant part of a populated island.
Historical Impact: concerns about historical evacuations and fatalities.
Development score: it groups indices related to the exposure of local and regional aviation, power and transportation infrastructure, major development around the volcano.
#var total=25 variables
(0-10) (0-4) (0-3) (0-3) (0-oo) (0-2) (0-oo)

7. Volcanic Threat of Central American Volcanoes
These are the results: the volcanic threat scores of 24 volcanoes in Guatemala, El Salvador, Nicaragua and Costa Rica, and, for comparison, 10 U.S. volcanoes categorized as high or very high threat volcanoes in the NVEWS analysis.
The plot also shows the Hazard and Exposure scores for the same volcanoes.
Within the range Kilauea-Augustine ( ) all the volcanoes rank as Very High Threat Volcanoes. The rest are High Threat (San Vicente-Okmok).
At least 22 CA volcanoes can be considered as Very High Threat based on the NVEWS classification, with several large volcanoes (Atitlan, Santa Ana, San Cristobal, Irazu) in the top part of this ranking.
These results may not be very accurate, particularly because of the little information available about the eruptive activity of some volcanoes.
Very High threat
High threat

8. Volcanic Threat of Central American Volcanoes
Now, as an example, imagine that we go to study Agua volcano and we discover that there was an eruption VEI=4 within the last 5000 years, another big eruption of VEI=5, and an eruption recurrence of a few thousand years, and with Holocene pyroclastic flows. All these values are possible for a volcano like Agua. As a result, the threat score for Agua increases and, perhaps, we realize that we should put more attention and efforts to elaborate a more complete hazard assessment.
For Agua, now max known VEI=5-6, it had an eruption VEI=4 within the last years, eruption recurrence between and several thousand years, and with Holocene pyroclastic flows
Very High threat
High threat

9. Vulnerability
Volcanic hazards are not the most important issue in Central America.
Even among natural hazards, volcanoes are not the one that is in most peoples minds (Hurricanes, Earthquakes, Landslides…)
Volcanoes are very far from the worst problem facing people in Central America, even though they are part of people’s live. In CA volcanoes enrich tropical soils, create forest environments and biodiversity/tourism.  So most days they really are more a plus than a minus. Even among natural hazards, volcanoes are not the one that is in most peoples minds (Hurricanes, Earthquakes, Landslides…)
Besides, in many places in Central America, poverty, health and other social issues are huge and compelling, and they are simply more important issues for most people.   The cost of volcanic hazard mitigation efforts—monitoring, hazard mapping, outreach communication and education, etc., seems huge compared to its low ranking as the most serious and compelling social problem.  To do all the work at monitoring, mapping and especially outreach education seems far too costly to justify.
BUT, the volcanic THREAT IS THERE….
In many places in Central America, poverty, health and other social issues are huge and compelling, and they are simply more important issues for most people.

10. Population density around selected volcanoes
El Salvador, Nicaragua and Guatemala are characterized by a high population density around volcanic centers, in some cases with houses or ‘fincas’ built on the flanks of historically active volcanoes. Indeed, many people are obliged to inhabit hazardous areas because of the socio- economical environment they live in, and they become more vulnerable to natural disasters. Education and access to quality information influence people’s awareness of the threat that communities face living or working near active volcanoes. Furthermore, volcano monitoring and disaster mitigation plans in Central America are improving but they are still at a basic level.
The proximity of dense populations to volcanoes in these countries increases the likelihood of disastrous consequences from volcano-related events (eruptions and other events unrelated to eruptions (e.g. Casita volcano in Nicaragua, 1998))
Population was calculated using LandScan’s database (LandScan Oak Ridge National Laboratory)

11. Population density around volcanoes

12. Map of Volcanoes in Central America
In total, more than 20 million people live within 30 km from volcanic centers in Central America, which is about 50% of the total population.
This map shows all volcanoes active in the Holocene (white triangles) and historically (green triangles). The colors in the map represent the logarithm of the population obtained from the LandScan database (LandScan 2007).
On each volcano a circle of 30 km radius enhance the area and population most likely to be affected by volcanic events. In total, more than 20 million people live within 30 km from volcanic centers in Central America, which is roughly 50% of the total population.

13. This is an attempt to qualify the vulnerability of these countries.
Following Wisner et al. 2003, the vulnerability of a country to a natural hazard can be considered as the capacity of the country to anticipate, deal with, resist and recover from the impact of the hazard.
Comparison of the Human Development Index (HDI) between countries in Central America and the United States for 2005 (HDR 2007/2008).
(a) life expectancy at birth; (b) % aged 15 and above , in the case of the U.S. this value was estimated differently; (c) combined gross enrolment ratio for primary, secondary and tertiary school; (d) literacy rate and school enrolment combined; (e) PPP= purchasing power parity, income.
This is an attempt to qualify the vulnerability of these countries.
The HDI is one of the development indicators contained in the Human Development Report, published annually since 1990, commissioned by the United Nations Developing Programme (UNDP) for countries worldwide. It is based on three indicators:
life expectancy at birth, as a measure of population health and longevity,
2) education index, measured by adult literacy rate and the combined enrolment ratio for primary, secondary and tertiary schools, and
3) standard of living, measured by the Gross Domestic Product (GDP) per capita.
Thus, the Human Development Index yields a good perception of the relative vulnerability between countries. For instance, the lower HDI and greater population density around volcanoes in El Salvador, Nicaragua and Guatemala, compared to those of Costa Rica and United States reflects the higher vulnerability of these three countries to volcanic events. Moreover, the consequences of a major volcanic eruption in any of these countries would probably follow the positive correlation between HDI and number of deaths, and negative correlation between HDI and the cost of damage caused by natural disasters (Wisner et al. 2003).
Do people living in hazard zones have a place to go in case of an eruption (family, summer house)? Do they have a car? Do they lose everything?
Do people at risk know where to go to be safe? How easily can they get to that place?
Anticipation to a volcanic hazard improves with knowledge about the phenomena (obtained through applied research) and thorough monitoring of efforts.
The way the community will deal with the hazards and recover from them depends, in part, on an appropriate management of the crisis.
The capacity of the country to deal with the occurrence of the hazard and to recover from its impact can also be related to life expectancy and GDP, as they are related to access and quality of basic services as well as to ‘quality of life’. Anticipation, reaction and resistance to a volcanic hazard improve with knowledge about the phenomena (obtained through applied research), availability of relevant information about the evolution or characteristics of external triggers of the hazard (based on monitoring capabilities), and appropriate management of the crisis (related to the amount/type of resources involved). These aspects are somewhat linked to the level of education and GDP in the country.

14. Reducing the risk
Monitoring and understanding how individual volcanoes work are key aspects of risk reduction efforts.
In January 2009 we worked with IGN (Instituto Geografico Nacional) to start GPS measurements.

15. Conclusions
NVEWS’s methodology to rank hazardous volcanoes helps to focus the attention and effort on those volcanoes with highest threat.
At least 22 volcanoes in Guatemala, El Salvador, Nicaragua and Costa Rica are classified as Very High Threat Volcanoes based on the NVEWS-US ranking system.
Further work is needed to include more volcanoes in the database. Particularly, more field work must be carried out in order to improve mapping of volcanic areas and our knowledge about past eruptive activity.
Vulnerability to volcanic eruptions in Central America is relatively high due to the high population density around volcanic centers and other socio-economic aspects.
Geophysical/geological studies aimed at understanding the behavior of individual volcanoes, a well as the implementation of appropriate volcano monitoring, are fundamental steps towards the reduction of the volcanic risk and the likelihood of a disaster.
All these help to build awareness of the threat and potential eruptions.