MANILA, Jan. 20 (Xinhua) -- The Philippine scientists advised thousands of displaced residents to stay clear of a 14-km danger zone around an erupting volcano despite a momentary lull in activity in recent days.
Since Jan. 12, Taal volcano in Batangas province on Luzon island, approximately 66 km south of Manila, remained at alert level 4, the second-highest warning, indicating "a hazardous explosive eruption is possible within hours to days."
Towns near the volcano island, one of the most active volcanoes in the Philippines, were largely deserted after more than 200,000 people fled to safety since the volcano rumbled back to life a week ago. At least half have been crammed in evacuation centers set up by the government.
For the past 24 hours, the Philippine Institute of Volcanology and Seismology (Phivolcs) said in its latest bulletin on Monday it recorded 673 volcanic earthquakes including 12 low-frequency earthquakes.
"Such intense seismic activity likely signifies continuous magmatic intrusion beneath the Taal edifice, which may lead to further eruptive activity," the institute said.
The institute added that a steady steam emission, continuing tremors and the drying of Taal Volcano's crater lake indicated rising magma.
Phivolcs Director Renato Solidum said the signs, including earthquakes and ground deformation, pointed to an imminent explosive eruption, so the threat remained.
No people were killed in the week-long eruption. But scores of horses and farm animals left behind by villagers that fled the volcano island were buried under the dense ash after the Jan. 12 eruption. Dozens of birds also died from the clouds of ash emitted by the volcano, home to more than 50 bird species.
There are approximately 3,000 horses on the volcano island, according to reports. Tourist guides use horses to bring tourists near the crater of the volcano island with an area of around 24 square km.
Taal Lake has an area of approximately 239 square km with a lakeshore circumference of about 267 km. The government said there are about 2,761 villagers whose livelihood depends on the lake.
The lake harbors the Tawilis fish, the only freshwater sardine in the world. It is an endemic species of sardines that can only be found in Taal Lake. The lake is also a major production area for tilapia and milkfish.
The government said the lake is predominantly used for fisheries but has multi-resource uses such as recreation, tourism, navigation, the water source for Tagaytay, irrigation, and source of feeds for ducks.
"As a major tourist destination area, the lake is used for sight-seeing, boating, swimming, sailing, and water skiing," the National Economic and Development Authority said in a report.
"Tourism industry in the affected areas, particularly in Tagaytay City, has suffered a tremendous setback," Tourism Secretary Bernadette Romulo-Puyat said.
Located 600 meters above sea level, Tagaytay City has a cool climate. The verdant green volcano and the placid lake are best seen in this city on ridge. Tourists go to Tagaytay on weekends to buy fruits and vegetables, and eat at restaurants overlooking the volcano.
An active earthquake zone, the Philippines has frequent seismic activity due to its location along the "Pacific Ring of Fire."
The Philippine archipelago is dotted with at least 24 active volcanoes. The country is also lashed by around 20 typhoons each year.