The catastrophic quake that struck Haiti on Tuesday involved a collision of lethal circumstances: a massive, shallow eruption below a densely populated city with few, if any, building codes.
The magnitude 7.0 quake occurred near the boundary between two major tectonic plates, the Caribbean and North American plates.
Most of the movement along these plates is what is known as left-lateral strike-slip motion, according to the U.S. Geological Survey, with the Caribbean plate moving eastward in relation to the North America plate.
Kate Hutton, a seismologist at Caltech, said the quake was similar to those seen along the San Andreas fault: It was shallow, a fact that enhances the intensity and makes it more localized to the region right along the fault.
"We are not surprised by any of it," Hutton said.
The Haiti quake had many similarities to the 1989 Loma Prieta quake in Northern California. That quake, said Tom Heaton, director of Caltech's Earthquake Engineering Research Laboratory, "caused a lot of damage, but it wasn't a disaster like this in terms of the number of people injured and killed."
For engineers and others well versed in the strict guidelines that California, Japan and other quake-prone zones mandate, the devastation seen in Haiti -- and other developing countries that have been hit by similarly sized temblors -- is horrifying but understandable. They blame the high numbers of earthquake fatalities in developing countries on poor building construction and rapid urban growth.
Before about 1950, a given-sized earthquake would do about the same amount of damage in the developed and underdeveloped world, said Ross Stein, a geophysicist with the U.S. Geological Survey in Menlo Park, Calif. Now the loss of life is typically 10 times higher in developing countries and the damage can be as much as 100 times higher, he said.
When a magnitude 7.9 earthquake rocked China's Sichuan province in 2008, schools, hospitals and other public buildings collapsed, contributing to the huge toll -- about 87,000 dead and missing. Shoddy school construction was blamed for the deaths of about 5,000 children.
The Chinese government was criticized for failing to impose strict building regulations, which it pledged to remedy.
Farzad Naeim, president of the Earthquake Engineering Research Institute, said that the quake in Haiti demonstrates "the same bad history, the nightmare, being repeated over and over again."
Naeim said that older construction in the region was built at a time when "people didn't know better." And new construction, he said, has not kept pace with advances in earthquake engineering, including reinforcements that are standard for new construction in California.
Turkey had a "very advanced code" in 1999 when a magnitude 7.4 earthquake killed at least 17,000 people, said Stein, who has worked extensively in the country. But the government left it to contractors to do their own inspections, he said.
In a city like Istanbul, "you are not really going to get anywhere by making rules," he said. "Many, many people are just pouring into the area without anything, and they knock down some trees and put a tent up. And the next year it's a shack. And the next year it's kind of a building. And the next year they start adding a floor as their family grows or other relatives come into the area.
"So here I am worrying about construction standards, but in reality so many of the buildings are built without any ownership, without any architect or engineer or anything," Stein said.
"What you have to do is train people to build stronger buildings with the means at their disposal."
Brian Tucker heads a Palo Alto-based group, GeoHazards International, that works with communities in developing countries to do just that. But he said that people "tend to treat earthquake disasters as God-given and controlled by God," especially in countries with many other pressing problems.
"I try to respectfully tell people that the earthquake disaster is in our hands," he said. "It's not like a comet coming from out of space that you have no way of anticipating."
Stein, of the USGS, said that part of the problem is that scientists have spent much of their time trying to understand the earthquake risks in California, Japan and other well-off parts of the world with high seismic hazards, while ignoring poorer and more densely populated parts of the world.
That's why the United Nations Development Program and other international agencies have been helping vulnerable countries -- including Jordan, Bhutan, China, Fiji, India and Iran -- to improve planning for earthquakes. The U.N. advises governments to upgrade schools, hospitals and other public buildings to better withstand earthquakes; to impose stricter building codes; and to develop evacuation, rescue and contingency plans.
Jordan Ryan, director of the UNDP crisis bureau, said his agency estimates that 60 million people have been affected by quakes in the last 10 years.
Ryan said there had been progress in getting the issue onto the agenda of some governments. "It's a very difficult argument to make," he said.
"It's like the old insurance argument: 'Who cares about prevention? We don't have enough money. We're a poor country.' "