????繼上周五日本遭遇8.9級地震和毀滅性的海嘯襲擊后，本周一投資者紛紛逃離日本股市，當地股指重挫6%。這次日本歷史上損失最慘重的大地震重創當地電力基礎設施，未來龐大的重建支出將使早已捉襟見肘的政府預算雪上加霜。

????過去一年，美元兌日元跌幅達10%，你或許以為此次（日本大地震后）美元會出現反彈，畢竟日本的財政狀況看上去可能會比美國還要糟。

????但美元未現振作。周一交易時段，美元走勢平平，美元/日元僅比1995年創下的歷史低點高出約2日元。1995年美元/日元創下歷史低點，正是發生在歷史上同樣慘烈的自然災難——阪神或稱神戶大地震震后3個月。

????究竟什么才能讓美元上漲？鑒于美國經濟復蘇跡象喜憂參半，而美聯儲承諾將長期維持接近零利率水平，美元要上漲看來很難。

????“僅僅由于日本遭受了重大自然災害，并不意味著日元會貶值，”野村證券（Nomura Securities ）分析師上周日在發送給客戶的報告中指出。

????日元匯率能保持高位的一個原因是保險公司為支付索賠，將資金匯回日本。野村證券估計未來幾個月此類資金匯回將達到80-110億美元——數額龐大，但外匯策略師珍斯?諾德韋格 認為，這樣的數額并不“足以左右日元整體資金流格局”。

????諾德韋格和野村證券的其他分析師還指出，未來幾個月對日元資金流影響更大的一個因素可能是避險意識抬頭，投資者在經歷了兩年的股市反彈后已變得更加謹慎。

????如果日元匯率上升至1995年創下的歷史高點，日本央行很可能會在外匯市場賣出日元、買入美元，以便將匯率維持在不會過度抑制國內經濟增長的水平。這種干預通常會使其他央行不快，但迫于形勢，他們也只能苦笑了之。

????"短期內，日元的強勢走勢可能得到強化，但我們認為現如今當局干預的可能性比震前更高了，”野村證券的泰庫克?塔納卡寫道，“假如出現負面的連鎖反應，即地震損害導致日元進一步走強，日本當局出手阻止日元升值可能情有可原。”

????當然，美元/日元的積弱走勢并非孤立現象。過去十年，貿易加權的美元指數跌幅超過1/3。此外，雖然葡萄牙是否需要救助仍是個問題，但歐元/美元仍徘徊于52周高點附近。

????美國經濟增速將快于歐洲和日本的預期，目前看來對美元似乎毫無助益。

????不過，Tanaka和其他分析師們預計，隨著全球復蘇力度增強，以及美聯儲逐步取消對經濟的支持性舉措，未來幾年日元/美元有望從80附近的高點降回至90附近。但正如過去幾天所示，如今哪怕是最基本的預測也面臨很大風險。

????Investors fled Japanese stocks Monday, sending market indexes down 6%, in the wake of Friday's 8.9-magnitude earthquake and a devastating tsunami. Japan's costliest quake ever left power infrastructure in tatters, promising that an already stretched government budget will be strained further by massive rebuilding costs.

????You'd think that might be a recipe for a snapback rally in the dollar, which has lost 10% against the yen over the past year -- at a time when Japan's fiscal picture has if anything come to look even more desolate than ours.

????Yet the dollar failed to snap out of its torpor. The U.S. currency was flat in trading Monday, leaving it just 2 yen or so from its all-time low against the yen – a record that was set in 1995, three months after a comparably costly disaster, the Great Hanshin or Kobe earthquake.

????Just what has to happen to get the dollar to rise? With the U.S. recovery sending mixed signals and the Federal Reserve pledging to hold interest rates near zero for a long time, the bar seems to be set pretty high.

????"Just because Japan has suffered substantial damages does not mean that the yen will weaken," analysts at Nomura Securities wrote in a note to clients Sunday.

????Part of what's keeping the yen high is the flow of funds back into Japan for the payment of insurance claims. Nomura estimates these at $8 billion to $11 billion over coming months – a substantial sum but one that foreign exchange strategist Jens Nordvig says is not "sufficient to dominate the overall yen flow picture."

????He and others at Nomura say a bigger factor driving fund flows into the yen in coming months could be a rise in risk aversion, as investors take a more cautious stance following a two-year-long stock market rally.

????If the yen rises to challenge the 1995 high, the Bank of Japan might well start selling yen and buying dollars in foreign exchange markets, in a bid to keep the exchange rate at a level that doesn't choke off too much domestic growth. This is not usually a move that's apt to make other central bankers happy, but they will grin and bear it given the circumstances.

????"Over the short term, the strong yen bias could increase, but we think authorities are more likely now than before the earthquake to intervene," Nomura's Taisuke Tanaka writes. "If a negative chain reaction were to occur in which the damages from the earthquake lead to a further strengthening of the yen, Japanese authorities would likely be justified in taking action to stem the yen's appreciation."

????The dollar's weakness against the yen is anything but isolated, of course. The trade-weighted dollar index is down by more than a third over the past decade, and the euro continues to trade near a 52-week high in spite of questions about whether Portugal will need a bailout.

????The notion that the U.S. economy will outgrow Europe and Japan doesn't seem to count for much at the moment.

????That said, Tanaka and others expect to see the yen pull back from its highs near 80 to the dollar to trader nearer 90 over coming years, as the global recovery gains strength and the Fed slowly removes its support for the economy. But as the past few days have shown, there are an awful lot of risks looming over even the most basic forecast nowadays.