Few volcanoes on Earth pose as much of a potential threat to human life as Taal in the Philippines. It's a caldera volcano that last erupted in 1977 and which has over 24 million people living within ~60 miles (100 km) of it. Taal has the potential for large explosive eruptions that could spread ash across much of the Philippines, including the capital, Manila.
On January 12, Taal woke up from its more than 40 year slumber, producing an explosive eruption from its central vent inside Lake Taal. The continuing explosions have been sending steam ash up over 32,000-49,000 feet (10-15 km) above the volcano. Ash fell on many towns near Taal and the international airport at Manila has closed in response. Thousands of people living on the shores of Lake Taal have been evacuated due to the threat of a potential tsunami in the lake if a larger eruption occurs.