By Ben Berkowitz and Julie Steenhuysen
(Reuters) - Moore, Oklahoma, has had the bad luck of being hit by two highly destructive tornadoes, both in the month of May, 14 years apart.
But the Moore that got struck on Monday is not the same as in 1999. Like a lot of towns across America and in the so-called "Tornado Alley," rapid growth has made it a bigger target, vulnerable to more damage.
The tornado, with winds that may have topped 200 miles per hour, killed at least 24 people and injured hundreds more, with many of the casualties children from two schools that were destroyed.
Local media said the storm was much more destructive than the tornado that laid waste to Moore in May 1999. At the time, that storm was the most destructive in history by insured loss ($1 billion), later eclipsed by two 2011 tornadoes in Joplin, Missouri and Tuscaloosa, Alabama.
Between 2000 and 2011, Moore's population grew by about 34 percent to 56,300, according to U.S. Census Bureau data. Over the same time, Oklahoma's population grew 9 percent and the U.S. population grew almost 10 percent.
"Every so often, (a tornado) will hit a city. Sometimes you may get clusters where there are several of those hitting in a given year. Other times you will go years and years without that happening," said Bob Henson of the National Center for Atmospheric Research.
"The U.S. population is growing and more territory is covered by homes and businesses than used to be the case. So the targets are getting larger."
Insurance industry experts call the phenomenon "disaster amnesia." People forget how badly devastated a region has been and focus only on what it can become through rebuilding.
One of the best examples is the Miami-area community of Homestead, all but obliterated by Hurricane Andrew in 1992 but since rebuilt and now doubled in population.
'SMACK IN THE HEART'
In fact, this was at least the third severe tornado to strike Moore over the last 15 years - a fact scientists called interesting but not indicative of the town being any more susceptible than any place else.
"Oklahoma City is smack in the heart of the most prone area where these conditions come together in the most dangerous way at (this) time of year," said Tim Doggett, senior principal scientist at disaster modeling company AIR Worldwide. "When things happen with some sort of random aspect to them, people look for patterns."
After a record number of twisters in 2011, volume has actually dipped of late. Last year was the first time in at least 20 years that fewer than 1,000 tornadoes touched down in the United States.
"Until the breakout this week, it's been a very quiet year for tornadoes in the United States," said Anthony Del Genio, a climatologist at NASA's Goddard Institute for Space Studies.
While it can be tempting to wonder whether severe events like this week's tornadoes are part of a bigger pattern, he said, "it's always good to remember that we went through a very quiet period leading up to this."
(For a government map of the most severe tornado strikes since 1950, click here: http://www.spc.noaa.gov/faq/tornado/f5torns.html)
LOSSES STILL UNCLEAR
The German reinsurer Munich Re has estimated tornadoes caused about $40 billion in insured losses in the United States in 2011 and 2012. Since 1980, average thunderstorm losses (including tornadoes) have risen sevenfold.
Though the scope of the damage seems obvious, it will be days before there is any sense of just how much the Moore storm has cost the insurance industry.
One problem is a lack of precision. As good as the science may have become, it remains hard to predict where and when a tornado is likely to hit in future, making it hard for insurers to fully model their exposure.
I really think (insurers) would like to know a much more precise location level ... and even in tens of thousands of simulated storm years that's a difficult question to answer," AIR's Doggett said.
Catastrophe bond investors, who have about $1 billion in exposure to U.S. tornado risk, were especially on edge Tuesday. One such bond was wiped out by 2011's record tornado season, putting a chill in that market.
USAA, the insurer that caters to military veterans and their families, said it had been unable to get its team of 120 adjusters into Moore. A spokesman said the company already had more than 350 claims, ranging from hail damage to total loss.
State Farm, the largest home and auto insurer in Oklahoma, said Tuesday it did not yet have claims numbers compiled, as its adjusters have not been able to get close to Moore either. A spokesman told Reuters it had already started receiving calls, though - including from one customer whose only remaining possession in the rubble of their home was a copy of their insurance policy.
(Editing by Mary Milliken and David Gregorio)