Tourists have been banned from a misty, picturesque island in a crater lake south of Manila because volcanic activity detected there could precede an eruption, scientists said Tuesday. Rising magma under Taal volcano was increasing volcanic earthquakes, detectable only by instruments, and raising the temperature of the lake, said volcanologist July Sabit of the Philippine Institute of Volcanology and Seismology. The island's 5,000 residents should prepare for a possible evaculation, Sabit said. Taal, about 45 miles (75 km) south of Manila and one of the Philippines most-visited sites, is off-limits to tourists as of Tuesday, he said. The volcanology institute issued a level 2 volcanic alert out of a possible 5, indicating that “the volcano is undergoing magmatic intrusion which could eventually lead to an eruption.” Seismographs recorded 32 volcanic earthquakes in just 24 hours ending early Tuesday. There also has been a “significant” rise in the temperature of the crater lake, in addition to increases in dissolved chemicals associated with volcanic rocks, the institute said. Taal island, most often reached by wooden boat, is a favorite destination among tourists who marvel at the site of a volcano rising from the middle of a lake. Some residents work as tourist guides, but most fish and farm. Rene Mendoza, chief of Tabla village – one of five villages on the island – said some women and elderly residents left because of the institute's warning, but most people are staying put. Most families on the island volcano own motorized outriggers they can use if an evacuation is ordered. The volcano has erupted more than 30 times since the 16th century. An eruption in 1911 killed nearly 2,000 people. A mild eruption in 1977 caused no damage or injuries.