he U.S. Geological Survey. Six people have been taken to hospitals with minor injuries from falling debris, an ambulance service said. "We are being enveloped with dust. It is very, very scary," Christchurch Mayor Bob Parker told New Zealand's National Radio. Christchurch has been shaken by thousands of aftershocks since the 6.3-magnitude quake killed 181 people on Feb. 22. Two men who were salvaging windows from St. John's Church became trapped after one of Monday's temblors brought down the building's facade, the last wall standing after February's quake. Police said they were rescued and taken to a hospital with cuts and bruises. Another nearby building collapsed, but no one was inside. The mayor said more masonry fell from the badly damaged Christchurch Cathedral, sending up large clouds of dust. Fire Service spokesman Dan Coward said they were inundated by calls about burst pipes. He added that many people were "freaked out" by the latest jolts. People attending inquest hearings for victims of the February earthquake with that of the greater consumer market, where renewable fuels seem to have stalled. Corn ethanol, which represents 10% of fuel consumption in the U.S., has been criticized for having a dubious environmental record, and auto makers and refiners are resisting U.S. government attempts to increase the amount of ethanol blended into gasoline. Biodiesel production, a hot industry in 2007, has ground to a halt. Some point to electric cars as being a better alternative than biofuels to reduce fossil-fuel consumption in the U.S. But airlines, unable to electrify their planes, have been pushing biojet fuel forward. On June 6, the renewable replacement won approval for use in jet engines from ASTM International, the international technical standards-setting group. Biojet fuel is an advanced biofuel, chemically indistinguishable from petroleum-based jet fuel. The high cost and decades-long lifespan of aircraft make major changes in engine design impractical, making "drop in" liquid biofuels that work with existing infrastructure the best alternative, said Paul McElroy, spokesman for Alaska Air Group Inc. (ALK), which operates Alaska Airlines. "There are many details that need to be addressed [with biojet], but we believe this is certainly worth pursing," McElroy said. One such detail is obtaining steady supply. Only a handful of producers make the fuel, mostly in relatively small batches for testing with the U.S. military. These include Solazyme Inc. (SZYM), Honeywell International Inc. (HON) subsidiary UOM LLC and Dynamic Fuels, a joint venture co-owned by Tyson Foods Inc. (TSN) and Syntroleum Corp. (SYNM) that converts chicken fat into biojet. Although Astmi's seal of approval for use of the fuel should help to coax investors to the industry, production issues still remain, including developing raw materials that will yield the most amount of fuel. And some