MANILA, Philippines (AP) _ More than 200 earthquakes shook Mount Pinatubo on Friday and thousands were evacuated before landslides of debris as the volcano appeared to be nearing another violent eruption.

Monsoon rains caused debris exhumed in last year's eruption to flow down the volcano's slopes, forcing nearly 7,000 people from their homes. Officials closed bridges near the volcano, 60 miles northwest of Manila, for fear they could be washed away by debris-glutted streams.

The rains also touched off explosions of superheated materials spewed out during the June 1991 eruption, one of the biggest this century and the first by Pinatubo in 430 years. The explosions sent ash clouds nearly five miles high.

Last year's eruption killed nearly 700 people, forced the United States to close Clark Air Base, 10 miles from the volcano, and damaged Subic Bay naval base. It is believed responsible for altering weather patterns worldwide.

Pinatubo resumed its activity last month when lava began to ooze from the crater created in the 1991 eruption. Scientists say a dome of magma is forming on the crater, building up intense pressure inside the volcano.

On Friday, the Philippine Institute of Volcanology and Seismology reported 196 low-frequency earthquakes and 34 high-frequency quakes during the prior 24 hours, nearly double the number of the previous day.

Low-frequency quakes indicate magma is rising to the surface, which scientists say could signal a new eruption.

Jose Andres, director of the Office of Civil Defense, said volcanic avalanches, or lahars, up to five feet deep swept down on communities near the slopes. There were no immediate reports of casualties.

Scientists estimate that enough debris to blanket Manhattan a quarter-mile deep was piled on the slopes in 1991, and only 10 percent has been washed down so far.

Police Chief Superintendent Pantaleon Dumlao said about 6,900 people have evacuated from the towns of Concepcion, Bamban, and Moncada in Tarlac province north of Pinatubo.

In the Pampagan provincial town of Mabalacat, about 800 people were evacuated Friday from areas threatened by avalanches. They were being housed temporarily on Clark Air Base, which is now under Philippine control.