Preliminary Analysis and Classification of Natural Disasters

Preliminary Analysis and Classification of Natural Disasters S.C. Wirasinghe 1, H.J. Caldera 2, S.W. Durage 3 and J.Y. Ruwanpura 4 1,4 Professor, 2 Volunteer, 3 PhD Candidate 1 wirasing@ucalgary.ca, 2 jithamala.caldera@gmail.com, 3 swalawed@ucalgary.ca, 4 janaka@ucalgary.ca Department of Civil Engineering, University of Calgary, Canada. Natural events that cause deaths, injuries and property damage are identified as emergencies, natural disasters, catastrophes, calamities and cataclysms. We will define these levels in the order given as being of increasing seriousness. Selected natural events that are planned to be included in the comparative study include earthquake, flash flood, flood, forest fire, landslide, cyclone, lightning, tornado, meteoroid strike, tsunami and volcano eruption. The comparative analysis will focus on clear definitions; analysis of probability of occurrence; intensity; region of impact; deaths and major injuries. Key Words: Natural Disasters, Catastrophe, Calamity, Cataclysm, Disaster definitions, Comparative-analysis, Classification 1. INTRODUCTION The temporal and spatial distribution of disasters gives an overall picture about various occurrences in the world. The severity of these events depends on many factors. The literature uses different terminology such as disaster, catastrophe to describe the nature of these events. But, these terms do not give a clear sense of scale as there is no consistent method to distinguish them from one another. The vocabulary, context and the interpretations of each term is not fixed in the literature. 1) In this paper, the term disaster is used as a general word to represent event occurrences, although it is also recognized as a specific term under the classification in Section 4. The lack of a common terminology to identify the scale is a major issue in disaster related information management and processing 2). This can lead to inconsistent reliability and poor interoperability of different disaster data compilation initiatives 3). For example, the term disaster may be different from one database to the other and therefore a given event occurrence is recognized as a disaster in one database while another database records it as a catastrophe. The nature of the disaster (whether it is primary or secondary) is a main issue that raises problems in distinguishing one disaster from the other. One disaster may lead to another disaster resulting in conjoint disaster records and therefore the separation of the impact of of one type of disaster from the other can be problematic. Different databases that follows different entry criteria, may give different interpretations for the same event 3). Moreover, databases that compile disaster events at the country level face issues with disasters that have impacts at the regional or continental level. The same disaster event can have very different impacts in each country 4) and thus the interpretation of scale for the same event can be different from one country to the other. With these deficiencies that degrade the quality of the dataset, comparison of different events and obtaining a sense of scale are problematic and disaster managers may face inconsistencies in identifying the hazard potential, responding to the event properly and allocating resources for mitigation measures 5). Further, disaster compensation and insurance policies may not manifest a clear basis when there are deficiencies 1). These issues support the need to develop a consistent scale to understand the disaster continuum and develop a flat form for reliable and transparent data management process that facilitates relative comparison among various degrees of disasters 4)&5). The objective of this research is to initiate the development of a scale or scales to recognize natural disaster 1

events considering various parameters such as event magnitude, number of fatalities, affected population and impact area. We intend to use a statistically sound methodology to analyze past disaster records in developing a multidimensional scale that can be used for all types of disasters at different levels. As an initial step of this scale development process, we present a rough scale derived by analyzing the top ten fatality records for a selected set of disasters. Section 2 of this paper reviews various disaster definitions and proposes a clear set of definitions for the terms emergency, disaster, catastrophe, calamity and cataclysm. Section 3 presents a detailed profile about the origins and triggers of various disasters. In this section, we begin the analysis of the deadliest events reviewing physical aspects, prediction/detection, impact and mitigation measures for a selected set of disasters. The top ten fatality records of these disasters are used to conduct a comparative analysis and develop a fatality based scale in Section 4. Section 5 concludes the overall analysis. 2. REVIEW OF DISASTER DEFINITIONS The words disaster, catastrophe, calamity and cataclysm are used commonly in describing natural disasters of various magnitudes. The definitions of these terms as given by well known dictionaries are given in Table 1. We note that the words are used interchangeably. For example, the Oxford Dictionary describes a disaster as a catastrophe, and then defines catastrophes and calamities as disasters. Google describes a disaster as a catastrophe and a calamity as a disaster. On the basis of the descriptions and definitions given in Table 1, and commonly accepted understandings, we propose the following definitions of natural events. It is considered to be understood that each of the following refers to natural events that cause at least one fatality. EMERGENCY: A sudden natural event that causes damage, injuries and some fatalities DISASTER: A major natural event that causes significant damage, and many serious injuries and fatalities CATASTROPHE: A large scale natural disturbance that causes severe destruction, major amount of injuries and extensive fatalities CALAMITY: A very large scale natural disturbance that causes widespread destruction, massive amount of injuries and a great loss of life CATACLYSM: An extremely large scale natural upheaval, that causes widespread devastation, uncountable amount of injuries and unimaginable loss of life We have carefully avoided using the five words above to describe each other; rather we take the position that the order in which the words are arranged above from top to bottom is the commonly accepted understanding of the increasing severity of the events. There is increasing seriousness from event to disturbance to upheaval ; from damage to destruction to devastation, from serious to major to massive to uncountable ; and many to extensive to great to unimaginable. 2

Dictionary Emergency Disaster Catastrophe Calamity Cataclysm Oxford 6) A serious, unexpected, and often dangerous situation requiring immediate action A sudden accident or a natural catastrophe that causes great damage or loss of life An event causing great and usually sudden damage or suffering; a disaster An event causing great and often sudden damage or distress; a disaster A large-scale and violent event in the natural world Merriam- Webster 7) An urgent need for assistance or relief A sudden calamitous event A violent and sudden change bringing great damage, loss, or in a feature of the earth destruction A violent usually destructive natural event (as a supernova) A disastrous event marked by great loss and lasting distress and suffering Flood, deluge Catastrophe Dictionary.referenc e.com 8) A state, especially of need for help or relief, created by som e unexpected event A calamitous event, especially one occurring suddenly and causing great loss of life, damage, or hardship, as a flood, airplane crash, or business failure. A sudden and widespread disaster Geology. A sudden, violent disturbance, especially of a part of the surface of the earth; cataclysm. A great misfortune or disaster, as a flood or serious injury. Physical Geography. A sudden and violent physical action producing changes in the earth's surface. An extensive flood; deluge. Google Glossary 9) A serious, unexpected, and often dangerous situation requiring immediate action. A sudden event, such as an accident or a natural catastrophe, that causes great damage or loss of life. An event causing great and An event causing great and often sudden damage or sufferintress; a disaster. often sudden damage or dis- Disaster and distress A large-scale and violent event in the natural world. Thefreedictionary.com 10) A serious situation or occurrence that happens unexpectedly and demands immediate action. A condition of urgent need for action or assistance An occurrence causing widespread destruction and distress; A sudden violent change in the A great, often sudden calamity a catastrophe earth's surface; a cataclysm An event that brings terrible loss, lasting distress, or severe affliction; a disaster A violent upheaval that causes great destruction or brings about a fundamental change. A violent and sudden change in the earth's crust. A devastating flood. Wikipedia 11) A situation that poses an immediate risk to health, life, property or environment Table 1 Disaster Definitions A natural or man -made hazard resulting in an event of substantial extent causing significant physical damage or destruction, loss of life, or drastic change to the environment. An extremely large-scale disaster, a horrible event. A disaster, a terrible event Any catastrophic geological phenomenon (volcanic eruption, earthquake), the result of a sudden release of energy in the Earth's crust that creates seismic waves More generally any large-scale disaster 3

3. DISASTER PROFILE AND ANALYSIS OF DEADLIEST DISASTER EVENTS 3) &4), A disaster profile developed based on the nature of triggering events, as proposed in the given references is shown in Figure 1. The very basic classification of disasters is based on whether the event is natural or human-induced. Natural disasters can be grouped based on the origin namely; biological, geophysical, hydrological, climatological and extraterrestrial events. Further classification into main type, sub-type and sub-sub type divides broad disaster groups to specific disaster types. Figure. 1 Disaster Profile In the continuing discussion, we consider only the natural disaster events, and a selected set from the above profile are used for the comparative analysis. These disaster events are shown in Table 2. To analyze a global level dataset and minimize regional specificities, we ignore the winter disaster events that are specific to countries in cold regions. However, we will continue to study them for inclusion in future classifications. Further, slow-moving disasters such as droughts are not considered in this analysis as they do not usually cause direct fatalities and in many cases it is a secondary cause that leads to fatal incidents. Slow moving disasters including pandemics will also continue to be studied. Further, we include the falling of meteoroids that has gained much attention after the Russian meteor strike in 2013 that injured more than 1,000 people. The intention of the comparative analysis is to increase our understanding of how one disaster is different from another considering several factors. Table 2 provides definitions, magnitude and frequency information about the disaster set. Table 3 elaborates how these events are predicted or detected and the estimated time interval from detection to the actual occurrence. Analyzing the disaster events in recorded history, Table 4 highlights the highest cases of fatalities, injuries, impact area and economic loss for each disaster type. Table 5 discusses mitigation measures to cope with these disaster events. 4

Type Cyclone /Hurricane/ Storm Surge Physical Aspects Definition Magnitude Occurrence (Frequency/No. of Events) An intense tropical weather system with a well defined Cyclone-Tropical Cyclone Intensity Globally, about 80 tropical cyclones occur annually, circulation and maximum sustained winds of 74 mph (64 Scales; one-third of which achieve hurricane status 13) knots) or higher. In the western Pacific, hurricanes are Hurricane- Saffir-Simpson scale (Category called "typhoons," and similar storms in the Indian Ocean 1-5) 12) ; Storm are called "cyclones." 12) surge-surge height. Earthquake A sudden violent shaking of the ground, typically causing great destruction, as a result of movements within the earth s crust or volcanic action 6) Richter Scale 5)&14) Flash flood A sudden local flood, typically due to heavy rain 6) Inundation area, Height n/a Flood An overflow of a large amount of water beyond its normal Peak level of the water at a particular limits, especially over what is normally dry land 6) location in a waterway Forest fire Landslide Lightning Meteoroid A fire in scrub or a forest, especially one that spreads rapidly 6) A collapse of a mass of earth or rock from a mountain or cliff 6) The occurrence of a natural electrical discharge of very short duration and high voltage between a cloud and the ground or within a cloud, accompanied by a bright flash and typically also thunder 6) A small body moving in the solar system that would become a meteor if it entered the earth s atmosphere 6) Tornado A mobile, destructive vortex of violently rotating winds having the appearance of a funnel-shaped cloud and advancing beneath a large storm system 6) Tsunami A long, high sea wave caused by an earthquake or other disturbance 6) Volcano A mountain or hill, typically conical, having a crater or vent through which lava, rock fragments, hot vapour, and gas are or have been erupted from the earth s crust 6) Table 2 Physical Aspects Damaged area; Rate of spread 16) Damage area (no single measure of landslide magnitude exists.) 18) Flashes per unit area per unit time 19) Energy released, Minimum orbit intersection distance (MOID) and absolute magnitude (H) 20) Fujita scale 5) Smaller earthquake occur frequently, but annually only as many as 18-20 reach a magnitude above Ms 7. 100-year flood or 500-year flood to convey the idea of the frequency of a flood of certain magnitude 15) In Australia, around 52000 bushfires per year 17) n/a The average lightning flash density in Canada Highest 3+ flashes/km 2 / 19) 39,454- In the world -Meteoritical Bulletin Database, November, 9, 2009 21) More than 1000 tornadoes annually in the USA Wave Height, Number of waves, No. of events 19 from 1980-2008 22) Damage area Volcanic Explosivity Index On average 50-60 volcanoes are active each year 23) 5

Type Prediction/ Detection Ability to Detect and Track Mechanism Estimated Time Cyclone/ Hurricane/ Storm Surge Earthquake Flash flood Can be detected and tracked. Cannot be predicted accurately, general location is known but exact time and location is unknown 14) Can be predicted, but there are sudden onset floods as well Once formed, the path and intensity can be predicted using heuristic models, empirical observations, and super computers 14) Detection of foreshocks by dense local monitoring networks 24) Detection of sudden change in parameters by long term monitoring and examination of various sensors P-waves using data such as rainfall intensity, duration, sudden rise of water levels Flood Can be predicted Using Rainfall intensity measurements, river flow data and prediction models Days 25) Cyclone-Days; Hurricane- 1 week 14) ; Storm surge Few hours - Day About 20 Seconds 5)&14) Minutes-Hours Forest fire Approximate location and time can be predicted Using satellite, weather data to predict spread direction and intensity Using Fire Danger Rating to provide early warning of the potential for serious forest fires based on daily weather data 26) Up to Two weeks 26) Landslide Approximate locations can be predicted Lightning Meteoroid Tornado Tsunami Lightning areas can be detected but exact location is unknown Only large meteor strikes can be predicted (NASA) General location is known but exact time and location is unknown areas and arrival times can be predicted Volcano Cannot be predicted accurately, only the approximate time can be predicted through regular monitoring Table 3 Disaster Prediction/Detection Using landslide zoning maps Using the appearance of landslide warning signs Using lightning sensors to obtain electromagnetic pulse information 19) Minutes-Days Several hours prior to a thunderstorm. Space observation by ground based & satellite telescopes Days-Decades 25) Using Doppler radar, ground truth information, approximate location of a tornado occurrence can be predicted. Detecting sea level changes using tide gauge records 27) Using tsunami modeling techniques By closely monitoring of volcanoes, the risk levels can be estimated. Approximately15-30 minutes 14) Minutes-Hours 25) Hours-Days for prediction 30s before explosion 11) 6

Type Cyclone/ Hurricane/ Storm Surge Fatalities 500,000-1970 Bhola cyclone 11) Earthquake 830,000-1556 Shaanxi earthquake 11) Flash flood 2,200-1889Dam Failure-U.S.A 11) Flood 2,500,000-1931 China floods 11) Total No. of Affected People Cyclone- 29,622,000 - China P Rep, Tropical cyclone-2006 28) ; Storm surge - 100,000,000- China, Storm -2002 28) 45,976,596- China P Rep, Earthquake (seismic activity) 12-May-2008 28) 238,973,000- China P Rep, General flood-1998 28) Area Destroyed Hurricane Katrina 2005 flood in seven states of the U.S.A ;New Orleans,Louisiana was crushed 33) ; Storm surge- 23,500 km 2 -Myanmar 29) 2010- Haiti: Port-au-Prince, Petionville, Jacmel, Carrefour, Leogane, Petit Goave, Gressier 29) Economic Loss Cyclone- US$ 125,000 million-, Tropical cyclone, U.S.A -2005 28), Storm surge-us$ 125,000 million - U.S.A, -2005 28) Economic damage cost - US$ 210,000 million- Japan, Earthquake 2011 28) Economic damage cost- US$ 40,000 million - Thailand, 2011 28) Damage Extent Region -Countries City-Region 25) Village 25) City-Region-Co ntinent 25) Forest fire 1,200-1871 U.S.A Fire 11) 3,000,000 - Indonesia, Forest fire Oct-1994 28) Average 5million acres burn every year in the US 24) US$ 8,000 million - Indonesia, Forest fire-1997 28) Village-Region Landslide 100,000-1920 Ningxia, China 11) Lightning 4,000-1856 Greece- Secondary explosion -, Rhodes 11) Meteoroid Tornado 1,300-1989 Bangladesh- Tornado 11) Tsunami 230,273-2004 Indian Ocean 11) Volcano 92,000-1815 Indonesia- Mount Tambora 11) Table 4 Disaster s 4,000,000- Brazil, Landslide -1966 28) 1903: Heppner Flood-1903 U.S.A: 25% of the city 11) landscapes disappeared Economic damage cost - US$ 988.8 million - Peru, Landslide-1983 28) Not available Several square meters Annual lightning-related costs in Canada CAD 600million to CAD 1 billion 30) Not available Not available The Tunguska event 1908 - devastation of 2000 sq. km of Siberian forest 31) 11,000,009 - United States 2008(from 1980 to September 2008) 32) 2,481,879 22) Affected countries-sri Lanka, Indonesia, Thailand, India, Bangladesh, Myanmar, Maldives, Malaysia 29) 1,036,065 -Philippines, Volcanic eruption -1991 28) US$ 5,000 million U.S.A- 2003 (from 1980 to September 2008) 32) Economic damage cost - US$ 210,000 million Japan, Tsunami 2011 28) Economic damage cost - US$ 1,000 million -Colombia, -1985 28) Village 25) Village- City-Region 25) City-World 25) City-Region 25) 10 s-1000 s Km 25) 7

Type Mitigation Cyclone/ Hurricane/ Storm Surge Better housing construction methods; Public awareness programs; Storm-shelters, Early detection and warning systems Earthquake Improving earthquake resistance of structures; Early warning systems 33) Flash flood Maintaining the drainage system; Delimitation of flood areas and securing of flood plains regulations; "Turn around and don't drown" 11) Flood Forest fire Landslide Lightning Flood Barriers; Structural measures to improve flood safety in housing construction; Early warning systems; land use restrictions Maintaining a defensible space between houses and the outer edge of surrounding tree crowns; Maintaining a greenbelt immediately around the house using grass; Monitoring and early warning systems 28) Maintaining the natural slope preserving the forest cover ; Hazard zone mapping; Monitoring systems, where applicable; Land-use and building regulations; Early warning systems; Public awareness programs 34) Take shelter immediately, preferably in a house or all-metal automobile ; Stay away from tall objects and take shelter in a low lying area; Once indoors, stay away from electrical appliances and equipment Meteoroid Tornado Early detection and warning systems; path alteration; Safe evacuation methods of cities Early warning systems; Seeking shelter immediately Tsunami Buffer zone; Structural measures such as breakwaters, seawalls; Evacuation shelters, Early warnings ; Public awareness programs Volcano Avoid being in the path of flow of the molten lava; Avoid use of electronic goods; During a volcanic activity, the best place to be would be indoors Table 5 Disaster Mitigation 4. FATALITY BASED DISASTER CLASSIFICATION In this section, we consider the top ten fatality records for the selected set of disasters discussed under Section 3 to develop a fatality-based scale. Records of fatalities in the top ten extreme cases of all disasters are taken as one dataset and a frequency distribution is obtained. The frequency histogram is shown in Figure 2. The mean and the standard deviation of the dataset is 112,135 and 290,807. 70 Histogram of Fatalities 60 50 Frequency 40 30 20 10 0 0 400000 800000 1200000 1600000 Fatality 2000000 2400000 8

Figure.2 Histogram of Fatalities Based on the mean and the standard deviation, we develop a scale with seven levels that starts at emergency and expands the severity up to cataclysm (Table 6). Here, we use a straight forward method to define levels based on fatality ranges. We use the approximate values of mean (μ) 100,000 and standard deviation (σ) 300,000. The lowest limit of the scale is the occurrence of one fatality. This can be represented as μ-0.33333σ. The fatalities increase by an order of magnitude as the seriousness of the event increases. The derived fatality-based scale from emergency to the cataclysm level is shown in Table 6. Given the vast range of fatalities, we have sub-divided each of the events disaster and catastrophe, into types 1 and 2. Further studies will likely result in calamity and cataclysm also being sub-divided into two or more groups. An example for each of the event types is also given. Type Fatality Range Example µ-0.33333σ F < A small landslide that kills one person Emergency 1 F 9 µ-0.3333σ Disaster µ-0.3333σ F < Edmonton tornado, Canada -1987 that killed 27 10 F 99 Type 1 µ-0.333σ people Disaster µ-0.333σ F < Thailand flood-2011 that resulted in a total of 100 F 999 Type 2 µ-0.33σ 815 deaths Catastrophe Hurricane Katrina-2005, U.S.A that killed 1833 µ-0.33σ F < µ-0.3σ 1,000 F 9,999 Type 1 people Catastrophe Tohuku earthquake and tsunami-2011, Japan that µ-0.3σ F < µ 10,000 F 99,999 Type 2 killed 15882 people 11) Calamity µ F < µ+3σ 100,000 F 999,999 Haiti earthquake 2010 killed 316,000 people 11) Cataclysm µ+3σ F 1,000,000 F China floods-1931 death toll 250000 11) Table 6 Fatality (F) based Disaster Scale The minimum level of the scale, emergency is the situation when there is at least one fatality and less than ten fatalities. The highest level cataclysm is defined when there are fatalities exceeding one million. The levels covered by each disaster are indicated as and the levels not covered are indicated as x in Table 7. Here, the list of disasters has been ordered to show the increasing coverage of the scale. Type Flash Flood Forest Fire Lightning Tornado Volcano Land slide Cyclone/ Hurricane Earthquake Tsunami Flood Meteoroid Emergency Disaster Type 1 Disaster Type 2 Catastrophe Type 1 Catastrophe Type 2 Calamity Cataclysm Table 7 Disaster Classification According to this classification, local disasters such as flash flood, lightning cover the lower levels where as the disasters with potential regional or global level impacts cover all the levels. Meteoroid impact does not have fatalities in recorded history. However, it has the potential to vary from emergency to the cataclysm level. Its range can go from a small meteor strike that explodes in the atmosphere to a large asteroid that falls to the earth causing unimaginable impacts. A flood has the ability to reach the cataclysm level. Local disasters such as flash flood, forest fire, lightning and tornadoes go up to the catastrophe Type-1 level. This analysis provides an overall picture about the scale of each type of disaster. With this kind of a scale, it is 9

easy to recognize an event occurrence and enter it into a database. Although the analysis is subjected to many limitations, it provides a good foundation to develop an advanced scale to classify disaster occurrences worldwide. In this analysis we have not paid attention to events which are twin disasters; e.g. an earthquake and tsunami striking, or a hurricane and peripheral tornadoes impacting, the same area. Such twin events can cause the classification to jump one or more levels. Additionally, one can add infrastructure failure to an event or twin events. The nuclear plant failure subsequent to the Great North East Japan Earthquake and Tsunami is a good example. A meteoroid impact on land close to population centers, or into the ocean (causing massive tsunami s hundreds of meters high), or major infrastructure failures subsequent to some other natural cataclysm, could cause many million fatalities. Further we have not considered Armageddon events such as a major asteroid strike. 5. CONCLUSION This paper presents the initial stage of an ongoing work to develop a multidimensional scale to understand the disaster continuum. Here, the analysis is limited to only one dimension, i.e. fatalities. Moreover, the data pool is limited to only the top ten fatality records for a selected set of disasters. Hence, the analysis is far from complete and at this stage there are many more questions than answers. REFERENCES 1) Ilan Kelman, Addressing the root causes of large-scale disasters in Large - Scale Disasters, Editor: Mohammed Gad-ElHak, Cambridge University Press, 2008, p.94-119 2) Vagelis Hristidis, Shu-Ching Chen, Tao Li, Steven Luis, and Yi Deng, Survey of data management and analysis in disaster situations, The Journal of Systems and Software, Vol. 83-10, October 2010, p.1701-1714 3) Regina Below, Angelika Wirtz, Debarati GUHA-SAPIR, Disaster Category Classification and peril Terminology for Operational Purposes, Working paper, Common accord Centre for Research on the Epidemiology of Disasters (CRED) and Munich Reinsurance Company (Munich RE ), October 2009, 10p. 4) Petra, Löw and Angelika Wirtz2, Structure and needs of global loss databases about natural disaster, International Disaster and Risk Conference IDRC Davos 2010, Davos, Switzerland, June 2010, 4p. 5) Mohammed Gad-ElHak, The art and science of large-scale disasters in Large - Scale Disasters, Editor: Mohammed Gad-ElHak, Cambridge University Press, 2008, p.5-68 6) http://oxforddictionaries.com/ (detailed references are available on request) 7) http://www.merriam-webster.com/ (detailed references are available on request) 8) http://dictionary.reference.com/ (detailed references are available on request) 9) Google Glossary definitions (detailed references are available on request) 10) http://www.thefreedictionary.com/ (detailed references are available on request) 11) http://en.wikipedia.org/wiki/main_page (detailed references are available on request) 12) http://www.aoml.noaa.gov/general/lib/defining.html 13) http://earthobservatory.nasa.gov/features/hurricanes/hurricanes_3.php 14) Mohammed Gad-ElHak, Introduction in Large - Scale Disasters, Editor: Mohammed Gad-ElHak, Cambridge University Press, 2008, p.1-4 15) http://www.ess.uci.edu/~yu/class/ess124/lecture.25.floods.pdf 16) http://www.csiro.au/en/outcomes/safeguarding-australia/bushfiretypes.aspx 17) http://www.aic.gov.au/publications/current%20series/bfab/41-60/bfab059.html 18) F. Guzzetti, M. Galli, P. Reichenbach, F. Ardizzone, and M. Cardinali, Landslide hazard assessment in the Collazzone area, Umbria, Central Italy, Natural Hazards and Earth System Sciences, Vol. 6-1, January 2006, p. 115 131 19) http://www.weatheroffice.gc.ca/lightning/ 20) http://neo.jpl.nasa.gov/faq/#pha 21) http://meteorites.wustl.edu/meteorite_types.htm 22) http://www.statisticbrain.com/tsunami-statistics/ 23) http://www.nerc.ac.uk/publications/other/documents/naturalhazards.pdf 24) http://www.pdc.org/iweb/pdchome.html (detailed references are available on request) 25) Chan Wirasinghe, Approaches To Classifying Natural Disasters & Planning To Mitigate Natural Disasters Example of Indian Ocean Tsunami & Prairie Tornadoes, Power point presentation, York University, January 18, 2012 26) http://cfs.nrcan.gc.ca/publications/?id=26656 27) Wickramaratne, Sanjeewa, Design and Analysis of Tsunami Warning and Evacuation Systems, PhD Thesis, department of Civil Engineering, University of Calgary, 2010, 412p. ( http://dspace.ucalgary.ca/jspui/handle/1880/47911) 28) http://www.emdat.be/ (detailed references are available on request) 29) http://www.munichre.com/en/reinsurance/business/non-life/georisks/natcatservice/default.aspx (detailed references are available on request) 10

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