BATANGAS CITY?Disaster officials put nine Batangas towns on alert after volcanologists announced that Taal, the volcano closest to Metro Manila, was acting up.

Allan Loza, resident volcanologist at the Taal Volcano Observatory, said the alert level for Taal was raised to 2 at 8 a.m. Tuesday. Alert level 2 means magma was rising ?which could eventually lead to an eruption.?

The Regional Disaster Coordinating Council (RDCC) in the Calabarzon (Cavite, Laguna, Batangas, Rizal, Quezon) said there was nothing to worry about, however.

The nine Batangas towns put on alert include Agoncillo, San Nicolas, Sta. Teresita, Laurel, Lemery, Talisay, Tanauan City, Balite and Mataas na Kahoy.

Officials of the tourist city of Tagaytay in Cavite, which counts Taal as one of its attractions, were also asked to prohibit tourists from descending on the crater and entering the Daang Kastila Trail, which is considered to be a danger zone.

The RDCC said if the alert level hits 3, it was time for authorities to activate its contingency plan and enforce the evacuation of residents.

Taal has been on alert level 1 since Nov. 23, 2005. ?Changes in the activities of Taal Volcano are usually sudden,? said Vicente Tomazar, RDCC director.

Taal?s last eruption was on Oct. 3, 1977, but its most violent was on Sept. 28-30, 1965.

Loza said since April 26, the number of volcanic quakes in Taal continued to increase.

He said on May 24 temperature at the main crater lake increased to 34 degrees Celsius from 32 degrees Celsius last May 11.

On June 2, a low frequency type volcanic earthquake was detected while in the past 24 hours, 32 high frequency volcanic earthquakes were detected.

Steam was visible at the northern and northeastern sides of the main crater. Hissing sounds were also heard.

Renato Solidum, head of Phivolcs, said water around Taal?s crater adds to its danger.

?The thing about Taal is that it has water. And the interaction of hot magma and water is not good. If you drop a glass of water in hot water, it will explode. So water can contribute to an explosive eruption,? he said.

The other signs that an eruption was imminent, he said, was if islands around the volcano rose and water levels on the shore became lower.

?We verified this visually,? said Solidum.

The 311-meter high volcano has a total of 47 craters. It has erupted 33 times in the past.