UPDATE 1-Philippines warns of 'explosive eruption' as volcano spews ash

* About 8,000 residents ordered to evacuate
* Authorities warn of "volcanic tsunami" in lake
* Ash fall also prompts class, flight suspensions

(Recasts with higher alert level, adds flight and class
suspensions)
By Enrico Dela Cruz and Karen Lema
MANILA, Jan 12 (Reuters) - A volcano near the Philippines
capital spewed ash up to 15 km (nine miles) into the sky on
Sunday, prompting the evacuation of thousands of people, the
cancellation of flights and warnings of a possible explosive
eruption and volcanic tsunami.
Taal volcano, one of the country's most active, is in the
middle of a lake about 70 km (45 miles) south of the centre of
the capital, Manila. As tremors shook the area, volcanic
lightning flickered in the column of steam and ash.
The Philippine Institute of Volcanology and Seismology
(Phivolcs) raised its alert level to 4 out of 5 - meaning
"hazardous explosive eruption is possible within hours to days".
Phivolcs also warned of possible hazards of a volcanic
tsunami and rapid currents of hot gas and volcanic matter that
could hit areas around the Taal lake, a popular weekend getaway
from Manila.
Evacuation of about 8,000 residents of the volcano island
and other high-risk towns is underway, with about 6,000 already
out of the danger zone as of early Sunday evening, the National
Disaster Risk Reduction and Management Council told reporters.
Ash fell as far away as Manila, prompting the suspension of
flights at the capital's busy international airport. General
Manager Ed Monreal said the suspension would continue into
Monday because there was ash on the runway.
Local authorities cancelled school classes scheduled for
Monday and urged people to stay indoors.
President Rodrigo Duterte had instructed authorities to move
people within the perimeter of Taal out of the danger zone, his
spokesman said in a statement.
The ash plume was clearly visible from the nearby 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."