A large eruption at the La Soufrière volcano in the eastern Caribbean early Monday is sending a rapidly moving avalanche of hot rocks and volcanic ash down the mountain, raising fears that some communities could be destroyed. Satellite imagery show the eruption produced dangerous pyroclastic flows traveling faster than a river down the mountain in St. Vincent and the Grenadines as ash filled the air. “I suspect quite a bit of the mountain now, and the communities, the buildings and the structures that are on the mountain, are destroyed and damaged,” said Richard Robertson, the lead geologist w…