A widespread tsunami warning was in effect for some Pacific islands following the strong earthquake in Japan on Friday.

The Pacific Tsunami Warning Centre said the sea level readings confirm that a tsunami has been generated which could cause widespread damage.

A widespread tsunami warning was in effect for the Northern Marianas, Guam, Wake Is, China's Taiwan, Yap, Marshall Islands, the Philippines, Midway Is, Palau, Chuuk, Kosrae, Indonesia, Papua New Guinea, Nauru, Johnston Is, Solomon Islands, Kiribati, Howland- Baker, Hawaii, Tuvalu, Palmyra Is, Vanuatu, Cook Islands, Niue, Australia, Fiji, Wallis Futuna, Samoa, American Samoa, New Caledonia, Tonga, Kermadec Islands, French Polynesia, New Zealand, Easter Island (Chile) and Pitcairn Island.

The Pacific Tsunami Warning Centre said the authorities should take appropriate action in response to this threat.

A tsunami is a series of waves and the first wave may not be the largest.

The time from one tsunami to the next can be five minutes to an hour and the threat can continue for many hours as multiple waves arrive.

In its fourth warning issued, the Pacific Tusnami Warning Centre has issued the following tsunami arrival estimates for Pacific Islands:

Northern Marianas: 0901 UTC; Guam: 0917 UTC; Yap: 0952 UTC; Marshall Islands (Enewetak): 1021 UTC; Palau: 1030 UTC; Pohnpei: 1036 UTC; Chuuk: 1041 UTC; Manokwari: 1125 UTC; Jayapura: 1142 UTC; Papua New Guinea (Kavieng): 1132 UTC; Nauru: 1157 UTC; Solomon Islands (Panggoe): 1228 UTC; Kiribati (Tarawa): 1236 UTC; Hawaii: 1307 UTC; Tuvalu: 1338 UTC; Vanuatu (Esperitu Santo): 1416 UTC; Tokelau: 1417 UTC; Wallis-Futuna: 1435 UTC; Samoa: 1453 UTC; American Samoa: 1500 UTC; Cook Islands: 1500 UTC; Niue: 1535 UTC; Australia (Cairns): 1535 UTC; Fiji: 1537 UTC; New Caledonia: 1538 UTC; Tonga: 1605 UTC; Kermadec Islands: 1656 UTC; French Polynesia (Papeete): 1714 UTC; New Zealand (North Cape): 1723 UTC; Pitcairn Island: 2008 UTC; and Easter Islands at 2303 UTC.

UTC is the abbreviation of Coordinated Uiversal Time, which is the same thing as GMT in the broad sense.