The Bank of Japan unveiled fresh easing measures Thursday to kickstart the stuttering economy after its first policy meeting under new management, moves hailed by some analysts as game-changing.
The yen plunged on the news, sparking a huge swing in the Nikkei 225 stock index, with investors cheering the measures as Japan wrestles with a mixed bag of economic data and no clear sign of a firm recovery.
A moderate 5.0-magnitude quake struck east of the Japanese capital just as the bank announced its new measures, which were described by one analyst as a "huge regime change" steered by Prime Minister Shinzo Abe.
The conservative leader swept to a December election victory on a pledge to boost the world's third-largest economy and put an end to years of deflation that has crimped private spending and corporate investment.
Abe had tapped Haruhiko Kuroda, former head of the Asian Development Bank, for the bank's top job, as he publicly criticised previous BoJ management for being too timid in stoking Japan's economy.
Speculation over the meeting's outcome has been building for weeks, with analysts warning the new-look BoJ may have set an unrealistically high bar for itself and that any new measures on Thursday could disappoint markets.
But Tsuyoshi Ueno, economist at NLI Research Institute, described the moves as a "huge regime change in monetary policy".
"What the BoJ announced today met almost all policy measures that had been speculated in the market," Ueno added.
After wrapping up its two-day meeting, the central bank said it would embark on an aggressive spending programme, while pledging to meet a two-percent inflation target within two years, aimed at reversing years of falling prices.
Its purchases would include riskier assets such as exchange-traded funds (ETFs) and real-estate investment trusts, while the BoJ would also buy longer-term government bonds, aimed at pushing down long-term interest rates to encourage companies and individuals to borrow.
ETFs are similar to an index fund, but trade on the market like stocks.
The bank also said it would aim to boost the monetary base -- the amount of currency in circulation including commercial bank deposits in BoJ reserves -- by 60 trillion yen ($632 billion) to 70 trillion yen annually.
The moves would see the BoJ "enter a new phase of monetary easing both in terms of quantity and quality", as it pointed to a pickup in the economy which has been hurt by a poor trade picture overseas.
"Japan's economy has stopped weakening and has shown some signs of picking up," it said.
Yoshikiyo Shimamine, executive chief economist at Dai-ichi Life Research Institute, said the announcement "went beyond market expectations".
"Kuroda showed today that the Bank of Japan is now different from what it was in the past," he added.
The news out of Tokyo sent the dollar surging against the yen, providing a boost to Japan's exporters who have been struggling under the weight of a strong currency.
The dollar surged to 95.22 yen after the announcement, from 92.94 earlier in the day, while the euro also jumped to 122.18 yen from 119.39 yen.
The weakening yen also sent the Nikkei up 2.20 percent by the close, reversing losses earlier on Thursday, although the currency's tumble may renew criticism from abroad that Tokyo was intentionally driving down the value of its currency to help exporters.
Kuroda, who took over at the BoJ last month, has been talking up his plans for a renewed assault on the deflation that has plagued Japan's economy for years, calling it "abnormal" for a developed economy.