The 8.8-magnitude earthquake that struck on Friday, the strongest ever recorded in Japan, has inflicted great harm on the quake-prone archipelago.

The mega quake has set off a deadly tsunami up to 10m high that sent walls of water sweeping across coastal cities in the north, which forced many other Pacific countries and regions on high alert.

The death toll from the disaster expanded Saturday to around 600, and the total number of people who have died or are unaccounted for is feared to top 1,700, according to Japanese media reports. About 300 to 400 bodies were found along the waterline in Sendai, a north-eastern city that is worst pummelled in the tragedy.

According to Japan's Nuclear and Industrial Safety Agency, radioactive materials including cesium and iodine were detected in Fukushima No. 1 nulear plant.

Moreover, NHK video showed that a significant explosion occurred at Fukushima No. 1 nuclear plant at 3:30 p.m. local time, causing four injuries. The walls and roof of one of the four containment buildings were destroyed after the blast.

Following the explosion, the Japanese government asked residents living within a 10 km radius of the No. 1 and No. 2 nuke plants to evacuate, but later enlarged the scope to a radius of 20 km.

According to the fire agency, the number of partially or completely destroyed buildings has now reach some 3,400.

In port city of Rikuzentakata in Iwate Prefecture, the landscape was virtually submerged, with only a few buildings remaining in the urban area.

In Sendai city in Miyagi Prefecture, flat farmland and a considerable number of buildings near the coast were whisked away that offered no resistance.

A municipal official of the Futaba town in Fukushima Prefecture was quoted by Kyodo as saying that more than 90 percent of the houses in three coastal communities have been washed away.

Thirty hours after the massive quake happened, many roads in the affected areas are inaccessible, public transportations came to a halt in the hard-hit region, and power and cellphone are still out of service.

So far, at least 100 aftershocks have jolted the coastal areas of Japan including over 25 upper-5.0 magnitude tremors, with more expected to follow.

The economic loss of the quake and tsunami and its long-term impact is estimated at exceeding $100 billion, according to some economists.

(Xinhua News Agency March 12, 2011)