Fishing boats are pictured amid heavy winds and rain brought by Typhoon Rammasun (locally named Glenda) as it hit the town of Imus, Cavite southwest of Manila, July 16, 2014. [Photo/Agencies]

Tens of thousands of people in the Philippines took shelter in evacuation centers on Tuesday as a typhoon began pounding the country's eastern coast and authorities warned of giant storm surges and heavy floods.

The eye of Typhoon Rammasun was poised to strike Legazpi city in the eastern Bicol region in the early evening, with Manila and other heavily populated areas also expected to be hit early on Wednesday, the state weather service said.

"We are preparing for the worst," said Rafaelito Alejandro, civil defense chief of Bicol, an impoverished farming and fishing region of 5.4 million people.

More than 96,000 families have already moved to evacuation centers there, Social Welfare Minister Corazon Soliman said in Manila.

The Philippines is hit by about 20 major storms a year, many of them deadly. The Southeast Asian archipelago is often the first major landmass to be hit after storms build above warm Pacific Ocean waters.

Super Typhoon Haiyan unleashed 7-meter storm surges that devastated the coasts of the eastern islands of Samar and Leyte last year, killing up to 7,300 people in one of the nation's worst natural disasters.