Palisades , New York ( CNN ) -- About six weeks ago , a large earthquake devastated Haiti and killed over 200,000 people . Saturday , a huge earthquake releasing 500 times more energy , devastated Chile and killed hundreds . So why did the smaller earthquake kill so many more people ? And why the sudden spate of disastrous earthquakes in the Americas ? No , the apocalypse is not coming . No , the two earthquakes are not linked in any way . And no , Pat Robertson , you ca n't blame the Devil or the French . The real answers , for those comfortable with science and the Enlightenment , are tectonics and poverty . Of the many revolutions of the 1960s , the one that really mattered to geologists was the revolution of plate tectonics . Tectonics is the word geologists use to describe the process by which mountains move and rocks squeeze and crunch . In the sixties , new data from research cruises and from earthquake seismometers led to the realization that tectonics makes mountains slide sideways long distances . Earth scientists discovered that the Earth has a patchy skin of mobile plates a hundred miles thick and thousands of miles across , and that they move horizontally at a slow but irresistible pace . It 's where they collide that our problems begin . South America is a prime example of this process , one that geologists call `` subduction . '' It 's why we have the long chain of mountains called the Andes and it 's why countries like Chile and Peru suffer giant , destructive earthquakes every few decades . Off the coast of Chile is a tectonic plate called the Nazca Plate . Unseen by most , it has been inching its way towards the South American continent , and sliding underneath it , for well over a hundred million years . Since the day that Magellan first rounded Tierra del Fuego it has encroached by 130 feet in a roughly east-north-east direction . The Nazca plate does n't slide under the South American plate in an orderly fashion though . It moves in fits and starts , sometimes sticking and sometimes slipping , sometimes here and sometimes there . Along the coast of Chile , patches can get stuck for over a hundred years . When they do finally slip , they go with a bang . All that squeezing energy is released in seconds and an earthquake happens . On Saturday a patch roughly the size of Maryland came unstuck , unleashing one of the most powerful tremors ever recorded . Fifty years ago , a patch four times bigger and with an area of about 50,000 square miles , the size of Louisiana , slipped and triggered the Valdivia earthquake . Its magnitude has been estimated as at least 9.5 , making it the largest earthquake of modern times . Over millions of years , this tectonic squeezing has formed the Andes and raised the high desert known as the Altiplano . Elsewhere it has created the Alps , the Rockies , the Himalayas , and Tibet . It has also created and distorted some of the islands of the Caribbean , including Haiti . So that 's why some parts of the world suffer from big earthquakes that strike with irregular frequency , while other regions are seismically quiet : it all depends on where the plates meet and how fast they are running into each other . Knowing this helps us assess seismic risk and mitigate it . It helps us know where the strongest earthquake shaking will hit and roughly how often . Predicting when the shaking will hit is a much greater challenge , and geophysicists are working hard to reach that goal . In any case , prediction is not the real problem : poverty is . Poverty is what ultimately kills most people during an earthquake . Poverty means that little or no evaluation is made of seismic risk in constructing buildings and no zoning takes place . It means that building codes are not written , and even if they do exist they are difficult , or impossible , to enforce . It means the choice between building robustly or building cheaply is not a choice at all . Haiti is a tragic illustration of this . Weak building materials and poor construction standards share much of the blame for the grotesque numbers of fatalities , injured and internally displaced people . Of course it 's complicated . Earthquake shaking is a complex process and the chain of causation from earthquake source magnitude through infrastructural damage to human harm involves factors like the type of earthquake fault , its orientation , the hardness of bedrock or presence of wet soil , and so on . A lot also depends on the time of day the earthquake strikes in terms of how many people are inside buildings that could collapse . Population density , distance from the epicenter , and the depth of the rupture are the most important factors of all . Nevertheless , those countries most at risk of seismic tragedy are not simply those on tectonic plate boundaries , but also those with the least money to spend on protecting themselves . The opinions expressed in this commentary are solely those of Colin Stark .
Chile 's quake released 500 times more energy than Haiti 's , says Colin Stark . Score: 7 Quake damage partly due to level of poverty , quality of building techniques , he says .