Developments after major Japan earthquake

* Japan battles to prevent nuclear catastrophe as there is a hydrogen explosion at the No. 3 reactor of the quake-hit Fukushima Daiichi nuclear power plant,which is 240 km (150 miles) north of Tokyo.

* Tokyo Electric Power Company (TEPCO) says 11 people were injured in the explosion at the No. 3 reactor.

* Chief Cabinet Secretary Yukio Edano says the core container at the reactor is intact after the fresh explosion which is unlikely to have led to a large escape of radioactivity.

* U.S. warships and planes helping relief efforts have moved away from Japan’s Pacific coast temporarily because of low-level radiation from the stricken nuclear power plant.

* Prime Minister Naoto Kan says the situation at the nuclear power plant remains worrisome and authorities are doing their utmost to prevent damage from spreading.

* Earlier,TEPCO said radiation levels at the Fukushima nuclear power plant,which is 240 km (150 miles) north of Tokyo,had risen above the safety limit but this posed no immediate threat to human health. An explosion blew the roof off at reactor No. 1.

* Authorities have set up a 20-km (12-mile) exclusion zone around the Fukushima Daiichi plant and a 10 km (6 miles) zone around another nuclear facility close by.

* Strong aftershocks persisting in the stricken area.

* About 300,000 people evacuated nationwide and almost 2 million households without power in the freezing north.

* The Nikkei plunges more than 6 percent; yen falls against the dollar. Shares in Sony Corp and Toyota Motor fall sharply.

* The Bank of Japan offers to pump a record $85 billion into the banking system to soothe market jitters. Sources say the BoJ is expected to discuss easing monetary policy further at its rate review on Monday.

* TEPCO says rolling blackout to affect 3 million customers,including large factories,buildings and households.

* Nuclear safety agency rates the incident a 4 on the 1 to 7 International Nuclear and Radiological Event Scale,less serious than Three Mile Island,which was a 5,and Chernobyl at 7.

* Quake triggered tsunami up to 10 metres (30 feet). Waves swept away homes,crops,vehicles and submerged farmland.

* Total insured loss could be up to $15 billion,equity analysts covering the industry say. Disaster-modeling company AIR Worldwide estimates the insured losses from the Japan earthquake at between $14.5 billion and $34.6 billion.