A blast at a locally owned quarry here two months ago struck with surprising power. An earsplitting boom was followed by a violent trembling that shook homes and garages to their foundations, toppled lamps off tables and knocked one man over as he tended his backyard garden. In the investigations that followed, a government scientist said the ground shook because of an explosion at the Jefferson Quarry. But the mining company said its own research found that an earthquake had struck the city seven seconds after it set off charges. The resulting standoff has left homeowners wondering who will pay for all the cracked plaster and other damage, and whether it will be months or even years before legal action can resolve who's at fault. "Nobody wants to take responsibility for anything," said Ann Helgeson, who bought her house adjacent to the quarry just weeks before the ground shook. She was home with her young son that day when the house started to shake from the cellar up. Now, the