A massive 8.9 magnitude earthquake — fifth largest since 1900 — struck at 2:46 p.m. local time Friday (12:46 a.m. ET), centered approximately 100 miles east of Sendai city on Japan’s main island, Honshu.

The quake generated a tsunami of at least 23 feet, that swept boats, cars, buildings and tons of debris miles inland in Japan. Smaller swells struck other Pacific Rim countries, causing serious but far less extensive damage.

The confirmed death toll on Saturday stood at 686, but officials say they expect it to be far higher as they reach the hardest hit areas.

Authorities declared states of emergency at five nuclear reactors in Fukushima prefecture; the situation at the Tokyo Electric Power Co.'s Fukushima Daiichi nuclear ractor No. 1 was of highest concern, with the company saying it feared a possible meltdown of the radioactive core before an explosion on Saturday severely damaged the building around the unit.

Transportation and communications systems were largely paralyzed and large areas of the country were without power At least 1 million households remained without water.