MADRID (AP) — Officials say there is no sign that a volcanic eruption on the Spanish island of La Palma is coming to an end, four weeks after it began. The volcano on one of the Canary Islands off northwest Africa has so far destroyed more than 1,800 buildings, mostly homes. Prompt evacuations have helped avoid casualties on the island of some 85,000 people. Rivers of lava continue flowing slowly toward the sea, and some 7,000 people have had to leave their homes. The volcano has produced a constant rumble and roar, with dozens of minor earthquakes most days, and has covered a wide area with volcanic ash.