MANILA — Another potential eruption of Taal Volcano could be stronger than last week's explosion that drove tens of thousands to evacuation centers, authorities said Tuesday, as some residents haggled to return home and reopen businesses.

A fresh supply of magma or molten rocks from underneath Taal is moving towards the volcano's crater, vaporizing the water on its lake and creating steam, said seismology institute Phivolcs Director Renato Solidum.

If unreleased into the air, the steam could build up pressure and trigger an explosion, he told radio DZMM.

About 10 to 15 kilometers southwest of Taal, Phivolcs also spotted a separate "magma intrusion" or a narrow dike of molten rocks moving towards the volcano, which could feed its unrest, said Solidum.

"Kung mabilis po ang pag-akyat ng magma o di kaya'y maghalo pa sa tubig, posible pong malakas [ang pagsabog]," he warned.

"Marami pong mga ganyang salaysay o naisulat sa Taal na minsan ang mga nauna ay malakas, pero iyong sumusunod ay mas malakas," he added.

(If the magma moves fast or if it mixes with water, the explosion could be strong. There are many written accounts that the first explosion could be strong, but the next could be even stronger.)

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An ash cloud that Taal belched last Jan. 12 sent some 148,500 people to evacuation centers and damaged at least P3.2 billion worth of crops and livestock south of the capital.

The volcano remains under Alert Level 4, the second-highest in a 5-step warning system, meaning a "hazardous explosive eruption is possible within hours to days," the state seismology agency said.

Residents are prohibited from returning to their homes inside a 14-kilometer "danger zone" around Taal.

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Authorities and volunteer groups in Batangas are feeding pets abandoned by the evacuees to discourage them from returning home, said the province's disaster office chief Lito Castro. The local government is also evacuating and offering to buy residents' livestock, he said.

"Kung iyan po ang dahilan, e di alisin po iyong dahilan para sila ay pumasok pa doon [sa danger zone]," Castro said in a separate DZMM interview.

(If the animals are their reason for entering the danger zone, then let's remove this reason.)

TAGAYTAY BUSINESSES

Meanwhile, businesses in 8 low-lying barangays in neighboring Tagaytay, Cavite -- a popular tourist spot -- are barred from reopening due to Taal's threat, said Interior Undersecretary Epimaco Densing.

The interior department, he said, will let Tagaytay Mayor Agnes Tolentino decide on whether or not businesses in the city's mountain ridge could re-open after Phivolcs deemed that this area is safe from "base surge" or current of ash, rocks and hot gas that looks like an atomic bomb explosion.

Should the commercial establishments there re-open, these should have emergency plans to protect employees and customers from Taal's ashfall, said Solidum.

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NO MAN'S ISLAND

The Phivolcs chief also reminded the public to refrain from returning to Taal's danger zone, especially the island on its lake, even under the guard of lawmen.

"Wala naman pong oras kung kailan talaga mangyayari, kung sasabog man. Siyempre iyong uniformed personnel natin, pareho lang silang apektado kung halimbawang andoon sila sa danger zone, naglalagay rin ng buhay sa alanganin iyong mga kasamahan nating nagbabantay," he said.

(The explosion, if it will happen, has no definite timeframe. Of course, our uniformed personnel will be affected too if they are in the danger zone, their lives will also be put in jeopardy.

Taal, one of the most active volcanoes in the Philippines, erupted more than 30 times in the past 5 centuries, most recently in 1977. An eruption in 1911 killed 1,500 people and one in 1754 lasted for a few months. — With a report from Reuters