Natural disasters: The chaos to come

© 2005 Nature Publishing Group

903

In sheer numbers, the death toll of floods, earthquakes,tsunamis, volcanoes and cyclones is small — 80,000 inan average year. Even the recent spate of catastrophesranks surprisingly low among the scourges of human-

ity. With the Indian Ocean tsunami and the Kashmirearthquake, disasters in the past 12 months claimed morethan 400,000 lives — the highest toll since 1970. But morethan three times that number are estimated to have diedon Earth’s roads in the same period; more thantwenty times as many died of avoidable child-hood diseases.

To dwell on the averages, however, is to missthe point. Catastrophes are not average; theyare the great exceptions. Most of us have seenroad-traffic accidents, but few of us have witnessed a natural disaster. They are ruptureswith the everyday that change cities, countriesand sometimes whole regions forever. Theycan even change patterns of thought. The Lis-bon earthquake of 1755 and its associatedtsunami, which struck while the city’s churcheswere celebrating All Saints’ Day, shook the faithof millions and altered that century’s intellec-tual landscape irrevocably.

It is the fact that they are rare and exceptionalthat makes it very hard to plan for natural dis-asters. Problems that crop up less than once ageneration — even, in some cases, less thanonce a millennium — are easily overlooked.Experts can anticipate some natural disasters,but their predictions and assessments oftencount for little compared with the pressures of

population and development, which increase the number ofpeople in harm’s way. As more people crowd the planet, particularly in vulnerable coastal areas, they risk disasters ofunprecedented proportions. Hence the paradox that thetwentieth century, benefiting from the most advanced technology in human history, saw more deaths due to natural disasters than any previous century had. There iseven the chilling possibility that the current century will beat

the previous one’s tally of 3.5 million deaths. The science behind predicting disasters is

uncertain. But with the best geological andmeteorological knowledge in hand, along withmodels that assess the vulnerability of differ-ent populations (see ‘Insuring for disaster’,overleaf), experts are starting to quantify justhow grim the future will be. Steve Sparks, avolcanologist at the University of Bristol, UK,has looked at analyses of current trends by theGerman reinsurance firm Munich Re. “Theworld can now expect three to five majorevents per year, which each kill more than50,000 people,” he says.

The mechanisms behind these disasters arenot new; the basic factors that underlie vol-canic eruptions, earthquakes, cyclones andfloods are well understood, and so is the geo-graphic distribution of risk. But there are stillthree mysteries: where and when a disaster willstrike; what unforeseen consequences theremight be; and how to get policy-makers andthe public at large to take the problems, and theuncertainties, seriously.

THE CHAOSTO COMENatural disasters have wreaked havocon the planet in the past twelvemonths, and some say that things willonly get worse. Quirin Schiermeierassesses the world’s growingvulnerability to catastrophe.

TSUNAMISPast More than 60,000 people were killedin Lisbon in 1755 by an earthquake and theresulting tsunami (pictured). About 300,000have been reported dead or missing followingthe great Indian Ocean tsunami of December2004. Tsunamis can be triggered by a rangeof disturbances, including earthquakes,underwater landslides and asteroid impacts.Future Low-lying coastlines in Sumatra,China, Peru and the eastern Mediterranean areconsidered at greatest risk. Early-warningsystems, public education, and land-useregulation offer the best chance of saving lives.

NATURE|Vol 438|15 December 2005 NATURAL DISASTERS NEWS FEATURE

BET

TMA

NN

/CO

RBIS

AP/

EMPI

CS

CRE

DIT

15.12 News Feat Disasters 13/12/05 9:56 AM Page 903

Nature Publishing Group© 2005


NATURAL DISASTERS NEWS FEATURE NATURE|Vol 438|15 December 2005

904

Warning Center in Hawaii — the first set ofbuoys was installed last month. Critics chargethat the technology could rust at the bottom ofthe ocean long before the next big wavestrikes1, but to some extent this misses thepoint. Many holders of insurance never need tomake a claim, but that doesn’t mean it was sillyto buy a policy.

History lessonsLetting the past be a guide to the future is notentirely satisfactory. Hemant Shah is the presi-dent of Risk Management Solutions (RMS), acompany based in Newark, California, thatconstructs risk models for the insurance indus-try. He echoes the US defense secretary, DonaldRumsfeld: “The challenge for the industry reallyis to think about the unknown unknowns.”More thinking along those lines might have ledto a greater appreciation of the tsunami risk in the Indian Ocean. But analysis of the pastdoes at least provide data for imagining future scenarios — experts can envisage the conse-quences of a repeat of the Lisbon earthquake,for example.

A team led by Shinji Toda, of the Geologic Survey ofJapan in Ibaraki, and Ross Stein, of the US Geological Survey in Menlo Park, California, has been re-evaluatingseismic risks to Tokyo in light of past earthquakes. In areport submitted to the Japanese government, theresearchers found that a replay of the 1855, magnitude-7.3Tokyo earthquake that killed 7,000 people could devastatethe city and send shocks through the world’s financial mar-kets. The problem is that no one understands the 1855earthquake well enough to predict accurately when it

Public preparedness rarely keeps pace withscientific knowledge. “The science,” says Sparks,who recently organized a meeting on naturaldisasters at the Royal Society in London, “is notgetting through to policy-makers, planners andpopulations.” US meteorologists had oftenwarned that their worst-case hurricane scenariowould involve a storm breaking the protectivelevees around low-lying New Orleans. Andthat’s exactly what happened on 29 August withKatrina, which left 1,300 dead — the largestdeath toll from a natural disaster in the UnitedStates since the 1928 Okeechobee Hurricane.Geologists had long warned of the possibilitiesof large earthquakes along the Himalayan front,like the one that struck Kashmir in October, andin the Sumatran trench off Indonesia, where thetsunami was born last December.

The very enormity of the Indian Oceantsunami is, in fact, a good example of unfore-seen consequences. The seismic risk in the areawas known, but the scope of the resultingtsunami, which affected a dozen countries, wastotally unexpected. Unlike in Hawaii and Japan— where tsunamis are a relatively frequent phenomenon, and where education projects and early-warning systems exist — many people in southeast Asia,India and eastern Africa had never even heard of suchwaves. The death toll was particularly high in the ‘shadowzone’ near the Equator, where tropical cyclones rarely occurand people have lived safely by the sea for centuries.

Risk-management experts predict that a tsunami of similar scale is likely to happen only once every 500 years.Nevertheless, nations around the Indian Ocean are fund-ing an early-warning system similar to the Pacific Tsunami

The impact of natural disasters onthe insurance industry often bearslittle relation to death tolls. A pairof hurricanes from 2005 — Katrinaand Wilma — may together costinsurance companies a recordUS$40 billion. And Europeanwinter storms with almost nofatalities can still cost billions.

Such bills make modelling riskvital for insurers. Models helpcompanies adjust their policyprices to their ‘risk appetite’, decide how much reinsurance to buy and how much additionalcapital to hold.

In 1995, Lloyd’s of London beganasking its 66 underwritingsyndicates to report estimatedlosses from hypothetical disastersbased on historical examples.Scenarios included majorearthquakes in California, the US Midwest and Japan, andwindstorms in Florida and Europe.The resulting ‘realistic disasterscenarios’ help Lloyd’s to assessthe insurance market’s

vulnerability to big losses.With few major natural disasters

in the 1970s and 1980s, theinsurance industry was ill-preparedfor 1992’s Hurricane Andrew and1994’s Northridge earthquake.Together, these cost insurers

$30 billion; at least nine companieswere rendered insolvent. Othercrises, such as the 1995 Kobeearthquake in Japan and the 2001terrorist attacks on the UnitedStates, have also had an effect —over the past decade, the cost ofreinsurance has grown 40-fold.

To help insurance companiescope, risk-management specialistsdraw up models of disasters. They

can calculate the frequency of acertain size of event (see table) and tell an insurance company witha given portfolio how big a loss itcan expect.

The models usually consist ofthree modules. A high-resolution

hazard module predicts thephysical effects that might beexpected at a given point fromsources such as historical records,windspeed maps or seismic data. Avulnerability module then predictsthe damage that an event,depending on its strength andduration, would do to localbuildings and infrastructure.Finally, a financial module

calculates an insurance company’seffective losses given suchdamage, taking into considerationits portfolio and the location of its policies.

The models vary widely inrobustness. They work well forcalculating losses from hurricanesand earthquakes in the UnitedStates. But in places where there islittle information from historicaldisasters, from Australia toMorocco, risk modelling is difficultand uncertain.

And for some of the mostapocalyptic scenarios — ameteorite impact or a mega-tsunami in the Atlantic Ocean — modelling doesn’t work at all. “Itis a real concern for the insuranceindustry that no models exist forsome of the worst things that couldhappen,” says Iwan Stalder, head of catastrophe perils at ZurichFinancial Services in Switzerland.“But we have to accept that somerisks are simply unquantifiable forunderwriting.” Q.S.

Data provided by Risk Management Solutions

Size of event (measured in fatalities) Frequency of event

1 in 100 years

1 in 500 years

1 in 1,000 years

Earthquake

472,000

1,052,000

1,446,000

Flood

98,000

520,000

1,061,000

Volcano

34,000

74,000

97,000

Insuring for disaster

HURRICANESPast The Great Hurricane of 1780 killed22,000 in Martinique, St Eustatius andBarbados. In 1900, an unnamed stormwiped out the Texas island of Galveston(pictured) establishing Houston as the state’s main port. Future Experts point to several scenariosthat could be worse than August’s Katrina,including a category-5 hurricane racing up theUS east coast and into Manhattan. Low-lyingparts of eastern India and Bangladesh are athigh risk of large fatalities from flooding andstorm surges. Population growth along coastsincreases vulnerability.

UN

DER

WO

OD

& U

ND

ERW

OO

D/C

ORB

IS




905

might happen again, and thus to quantify the risk. “There’san enormous amount of uncertainty,” says Stein.

Tokyo’s peculiar vulnerability to earthquakes, whicharises from its position at the junction of three tectonicplates, is a chronic worry for the global financial system.But in casualty terms, there are places that concern seis-mologists more. The worst earthquake of the twentiethcentury, and possibly the worst in history, was China’sTangshan earthquake in 1976, which may have killed morethan half a million people. Some seismologists think thatthe ever-growing cities in earthquake belts across Asia,many filled with unstable buildings, mean that a million-fatality earthquake is possible in the near future; Sparksmentions Istanbul, Tehran and Sumatra’sPadang as likely sites. Tehran, a city of 12 mil-lion with what one expert at RMS calls “someof the scariest construction known to man”, is aparticular worry: just as Tokyo has the poten-tial for an earthquake with disproportionatefinancial impact, one in Tehran would have ahuge geopolitical impact.

Floods of fireVolcanic eruptions are also bound to do moredamage in the future than in the past, simplybecause more people live in their path. Heresome degree of warning is more likely than it iswith earthquakes, but it cannot be relied on.And although cities such as Naples, at the footof Italy’s Mount Vesuvius, face the most obvi-ous dangers, other situations could result inmore deaths. Robert Muir-Wood, chiefresearcher at RMS, notes that a major tragedycould happen if an eruption reached a majorcity just outside an immediate evacuation zone,to which people had fled for shelter.

An additional concern is that we have nohistorical experience of what a really large

Shattered: thedestruction caused bythe Indian Oceantsunami was largelyunforeseen.

volcanic eruption might look like. The twentieth century’smost lethal eruption, in Martinique in 1902, was far smallerthan the giants of the nineteenth century. The 1883 erup-tion of Krakatoa in Indonesia obliterated the island andsent plumes of volcanic ash drifting around the globe foryears, and the Tambora eruption of 1815 affected climateall over the world. Even mighty Krakatoa was at least anorder of magnitude smaller than the Santorini eruption,which effectively wiped out the Minoan civilization in theeastern Mediterranean around 1400 BC.

Hurricanes, by contrast, are more tractable. There arelimits to their size and destructive power, they have seasons, and their tracks can be forecast with some degree

of accuracy. They are also frequent enough forpeople to take seriously, especially if given theright sort of warnings and information. In theUnited States, the National Hurricane Centerin Miami, Florida, is responsible for issuingstorm warnings when Atlantic hurricanesthreaten the coast. It now produces maps,available on the web and through televisionbroadcasts, that forecast storm paths with anaccuracy that has improved by 50% in the past30 years.

Most coastal residents pay attention onlywhen a hurricane is threatening their particu-lar part of the coast, so this information has tobe targeted to the right place, at the right timeand in the right way. “Meteorology meansnothing to 99% of my viewers,” says SteveLyons, a hurricane expert and anchorman ofthe popular US Weather Channel. “We need totranslate the meteorology into impact. It’s liketelling people in a town very concretely: ‘It’sgonna blow your roof off, so you better run’.”

But it is not all about listening to the media.Teaching people how to notice warning signalsfrom nature — such as shaking ground or a

VOLCANOESPast The past two centuries have seen morethan a dozen volcano disasters that caused atat least 500 deaths. One such was Mt Pelee’seruption in 1902 (pictured). Affected regionsare mostly in the developing world, includingIndonesia, Colombia, Mexico, Guatemala,Martinique, Papua New Guinea, Cameroonand Congo. Future Were the 1815 eruption ofIndonesia’s Tambora to happen today, 15,000 people might be killed. Volcanologistsare struggling to develop timely warnings formountains that have lain dormant for manyyears and could erupt at a moment’s notice.

NATURE|Vol 438|15 December 2005 NATURAL DISASTERS NEWS FEATURE

POPP

ERFO

TO.C

OM

AFP

/GET

TY

IMA

GES




906

receding ocean — can save lives in all sorts of natural dis-asters. Other relatively simple measures include planningescape routes and evacuations, and reconsidering land usein regions threatened by floods, storms, landslides andavalanches. A 2004 World Bank report on the cost of nat-ural disasters in the 1990s estimates that $40 billioninvested in risk reduction and preparation could have cut

the decade’s final bill in half, from$535 billion to $255 billion. It alsoestimates that, over the past fourdecades, $3.15 billion invested inflood control by China has averted$12 billion in losses.

Such mitigation strategies haveworked to save lives most dramat-ically during floods, says Muir-Wood. In China, for instance, floodcasualties have dropped through-out the century, in part because ofinvestment in protection systemsand evacuation plans. In the 1930sand 1940s, 4.4 million people diedfrom flooding in China; in the1950s and 1960s, that numberdropped to 2 million, and by the1970s and 1980s it was 14,000.

Still, the Indian Ocean tsunamiand Katrina have highlighted thefailure of society as a whole to takepreventative action, says Maxx

Dilley, a geographer at the Disaster Reduction Unit of theUnited Nations Development Programme (UNDP) inGeneva. From international organizations to local decision-makers, those in charge are realizing that they need to knowhow natural events become tragedies. “A lot of things arecoming to a head,” says Dilley. “There is an internationalpush to focus more on risk identification and management,as opposed to post-disaster emergency action.”

Several organizations, including the UNDP, the RedCross and the International Strategy for Disaster Reduc-tion, have recently published reports outlining improvedrisk-management strategies2–4. They emphasize puttingmore resources into preparedness — restricting the expan-sion of cities in earthquake-prone regions, for example. Sci-ence, says Dilley, should be the basis of all these activities.But the fragmented research community is not positionedto provide the right input, he adds: “What you need areplanner-friendly common views, as opposed to highly spe-cialized scientific papers.”

To address the issue, a group of experts led by DavidKing, Britain’s chief science adviser, has suggested setting upan International Science Panel for Natural Hazard Assess-ment. Such a panel would function like the Intergovern-mental Panel on Climate Change, sorting through a flood ofscientific information and creating a generally accessiblesummary of the latest findings. And the UNDP and WorldBank are working with Columbia University’s Earth Insti-tute in New York on a project to identify high risks, and givegovernments and local planners the data to recognize them.

“This is the kind of information,” says Sparks, “that, hadit been available ten years ago, would have allowed governments in southeast Asia to take precautions againstthe tsunami.” ■

Quirin Schiermeier is Nature’s German correspondent.

1. Alversen, K. Nature 434, 19–20 (2005).2. Reducing Disaster Risk: A Challenge for Development (United Nations

Development Programme, 2004).3. World Disasters Report 2005 (International Federation of Red Cross and Red

Crescent Societies, 2005). 4. Living with risk: A global review of disaster reduction initiatives (International

Strategy for Disaster Reduction, 2004).

EARTHQUAKESPast The devastation of San Francisco in1906 (pictured) is legendary, but thedeadliest earthquake known happened inChina: at least half a million died in theTangshan disaster of 1976.Future Specialists point to China, theHimalayan front or the city of Tehran aspossible locations for the first earthquake tocause a million casualties. Events in Tokyo,California and the Mississippi Valley are likelyto cause the most economic damage.Improving construction standards andemergency plans could significantly reduce fatalities.

The death toll of theKashmir earthquake is still rising.

NATURAL DISASTERS NEWS FEATURE NATURE|Vol 438|15 December 2005A

P/EM

PIC

SBE

TTM

AN

N/C

ORB

IS

FLOODSPast Seven of the ten deadliest flooddisasters in the twentieth century haveoccurred in China. More than 6 million peopledied from drowning, starvation and diseaseduring the three biggest floods in 1931, 1939and 1959.Future China is building its controversialThree Gorges Dam, to be completed in 2009,in part to reduce flood risk. Central America,Bangladesh, Taiwan and elsewhere remain atrisk from heavy rains. Dams and otherbarriers, as well as re-naturalization of rivercourses, may help. Low-lying countries suchas the Netherlands are accustomed toinundations such as that pictured above, butclimate change may increase flood risk.

KEY

STO

NE/

GET

TY

IMA

GES



Documents

Natural disasters: The chaos to come