Taal, one of the world's smallest active volcanoes, sits in the middle of a lake about 70 km (45 miles) south of the centre of the capital, Manila. Authorities warned that an eruption could send a tsunami surging across the lake
Schools and businesses shut across the Philippine capital on Monday as a volcano belched clouds of ash across the city and seismologists warned an eruption could happen at any time, potentially triggering a tsunami.
Thousands of people were forced to evacuate their homes around Taal, one of the world's smallest active volcanoes, which spewed ash for a second day from its crater in the middle of a lake about 70 km (45 miles) south of central Manila.
"The speed of escalation of Taal's volcanic activity caught us by surprise," Maria Antonia Bornas, chief science research specialist at the Philippine Institute of Volcanology and Seismology told reporters.
"We have detected magma. It's still deep, it hasn't reached the surface. We still can expect a hazardous eruption any time."
Authorities warned that an eruption could send a tsunami surging across the lake.
More than 16,000 people were evacuated from the volcanic island and the area immediately around it - normally a popular tourist spot. Dozens of tremors set residents on edge.
Some tourists ignored the dangers and travelled to towns closest to the volcano to get a better look.
"It's a once in a lifetime experience for us," Israeli tourist Benny Borenstein told Reuters as he snapped photos of Taal from a vantage point in Tagaytay City, about 32 kms away.
In nearby Talisay Batangas, Vice Governor Mark Leviste said rain had turned ash to mud and trucks were needed to evacuate more people from remote communities.
"There is no power. Even water was cut, so we are in need of potable water," he said. "We are in need of face masks."
In Manila, masks sold out quickly after residents were advised to wear them if they had to go out. Some wore handkerchiefs across their faces as they breathed air tainted by the smell of sulphur.
Streets that would normally be snarled with some of the world's worst traffic were largely empty in the city of 13 million people.
Schools and government offices were closed on official orders. The stock exchange suspended trading and many private businesses shut for the day too.
Flight operations at Manila's international airport partially resumed, authorities said, after at least 240 flights were delayed or cancelled on Sunday.
One flight that did land carried President Rodrigo Duterte, who was coming back from his home city of Davao in the southern Philippines. He had been unable to fly on Sunday because visibility was so low.
One of the most active volcanoes in the Philippines, Taal has erupted more than 30 times in the past five centuries, most recently in 1977. An eruption in 1911 killed 1,500 people and one in 1754 lasted for a few months.
The island has been showing signs of restiveness since early last year.
The Philippines lies on the "Ring of Fire," a belt of volcanoes circling the Pacific Ocean that is also prone to earthquakes.
About 8,000 residents of the volcano island and other high-risk towns were being evacuated, with about 6,000 already out of the danger zone by Sunday evening, the National Disaster Risk Reduction and Management Council told reporters.
The volcano and its surroundings are a popular weekend getaway from Manila.
The drifting ash forced the cancellation of 172 flights in and out of the international airport on Sunday. General Manager Ed Monreal said flights would also be suspended on Monday because there was ash on the runway.
President Rodrigo Duterte's office ordered the suspension of government work in the capital and of all school classes in Manila and other areas affected by the ash. A statement advised private companies to follow suit.
In Manila, long queues formed in shops selling face masks as health officials warned of possible breathing problems for people with respiratory ailments and urged the public to stay indoors and use dust masks when going out.
"When I went to my car to bring my groceries, I saw it was covered in ash. So I hurriedly went back inside to buy a mask from a drugstore but they had run out," said Angel Bautista, 41, a resident of Paranaque city, south of the capital.
Taal's ash plume was clearly visible from the city of Tagaytay, a well-frequented viewing spot for the volcano.
"We were having lunch when we heard rumbling. We saw the volcano erupting. It rained and some small pebbles fell to the ground," Jon Patrick Yen, a restaurant customer in Tagaytay, told Reuters.
"I did not expect to see such spectacle. We just went by to eat."
Financial Markets Shut Down
Philippine financial markets were shut on Monday to ensure the safety of employees and traders.
The suspensions cover stocks, fixed-income, and dollar-peso spot trading.
Regular fixed-income trading and settlement operations were expected to resume on Tuesday, the operator of the country's fixed-income trading platform, PDS Group, said in a statement.
Separately, the Bankers' Association of the Philippines encouraged banks to exercise discretion to ensure the safety of their employees.
Clearing and settlement operations at the Securities Clearing Corporation of the Philippines have also been suspended, the Philippine Stock Exchange said.