Oil prices dropped below $100 a barrel today after a massive earthquake and tsunami devastated northeastern Japan, denting demand for crude from the world’s third-largest economy.

Officials estimate a 33-foot wall of seawater triggered by an 8.9 magnitude quake off the coast of northern Japan on Friday severely damaged the country’s energy infrastructure. The benchmark Nikkei 225 stock average fell more than 6 percent today.

“This disaster has in effect temporarily frozen the world’s third largest economy,” said Richard Soultanian of NUS Consulting. “It seems clear that Japan’s appetite for crude oil may be diminished in the near-term which should provide previously unforeseen slack in international oil markets.”

By early afternoon in Europe, benchmark crude for April delivery was down $1.42 at $99.74 a barrel in electronic trading on the New York Mercantile Exchange. The contract slipped as low as $98.47 earlier in the session and lost $1.54 to $101.16 on Friday.

In London, Brent crude was down $1.22 at $112.62 a barrel on the ICE futures exchange.

Three of Japan’s five largest refineries have been shut down, which will immediately crimp demand for crude. Japan is the world’s third-largest crude consumer at 4.5 million barrels a day, the second-largest net oil importer and the biggest importer of liquified natural gas and coal.

On the other hand, analysts said diesel use in Japan could be on the rise.

“The demand for diesel fuel to generate electricity should be higher, as the rationing of power is likely after numerous nuclear power stations have been switched off,” said a report from Commerzbank in Frankfurt.