一些投资者正在购买日本政府债券作为股市低迷之下更为安全的选择，而另外一些投资者则在购买日本政府债券信用违约掉期，因为他们认为，用不了多久日本政府就会拖欠债务。这两种投资者之间正进行着一场拉锯战。五年期日本政府债券的信用违约掉期价格正在飙升至历史新高。

    日本国债受到关注的原因很简单。由于向本国银行、保险公司和国民出售国债，日本目前已经债台高筑（预计今年将高达 GDP 的 228%）。其债权人一直允许利率保持在能够承受的范围之内，近乎于零。但债务负担如此之重，即便是利率的微幅增长也会将不可持续的国家收入消耗殆尽。

    当然，这里要说明一点，这种情况是不可持续的。根据国际评级机构标准普尔（Standard & Poor's）的一份报告，日本的人口老龄化将会促使承担大部分政府债务的机构——日本国内寿险公司和政府养老投资基金——成为净卖家，以承担与养老金有关的费用。

    总有一天，日本人口结构的变化会迫使其向国外买家借款，而这些国外买家很有可能会收取日本无力支付的高利率。如此一来，日本就会陷入债务危机。

    然而，这次地震也可能不会导致债券收益飙升，原因有二。

    首先，根据报道，这次地震未必会使保险公司赔付巨大的地震损失，因为仅有 18.5% 的日本家庭拥有地震保险。如果那些承保人不必进行巨额理赔，他们就大可不必清算国债之类的资产。

    事实上，日本债券依然稳定，灾后日元甚至更为坚挺。经济学家把这种现象归因为以下猜测：日本机构可能会出售美国国库券来募集资金，而且日本本土公司可能会将资金汇返该国以支付地震损失。日本是除中国之外美国债务的最大买家，当其弄清楚救援和灾后清理到底需要多少资金时，也可能会立即停止购买美国国库券。

    其次，根据日本银行的数据，日本持有本国债务的 95% 以上。所以即使国外投资者开始减持债券，这些债券也只是整个债券市场的一小部分。

    因此，虽然债务危机的恐慌和以前一样笼罩着日本，但这在震后短时间内恐难发生。日本政府债券的利率需由国外市场决定之时，才是日本债务问题“清算”之日。

    日本具有向本国机构和国民借款的能力，这在很大程度上加剧了日本对信用的依赖。而现在，在日本最需要保护的时候，同样的状况也许会保护其免受严酷的市场冲击。

    There's a tug of war happening right now between investors who are buying Japanese government bonds (JGBs) as a safer alternative to the sinking stock market, and investors who are buying credit default swaps on JGBs because they believe the country is will soon default on its debt. The price of credit defaults swaps on 5-year JGBs is hitting record highs.

    Here's a quick look at why people are scrutinizing Japanese sovereign debt. Japan has been able to rack up a massive debt load (expected to hit 228% of GDP this year) by selling JGBs to its own banks, insurance companies, and citizens. These lenders have allowed interest rates to stay at a very affordable near-zero percent. But with a debt so large, even a small increase in interest rates would start to eat up an unsustainable amount of the country's revenues.

    Certainly there's an argument to be made that this situation is unsustainable. According to a report from Standard & Poor's, Japan's aging population will push the institutions that hold the most government debt -- domestic life insurance companies and the Government Pension Investment Fund -- to become net sellers to support pension-related costs.

    The demographic shift will someday force the country to borrow from foreign buyers, who will likely charge higher interest rates that Japan can't afford to pay. And then you have your debt crisis.

    But there are two reasons that the earthquake may not trigger a sharp rise in yields.

    First, the quake is unlikely to force insurance companies to make massive payments for earthquake damage, since only about 18.5% of Japanese households have earthquake insurance, according to reports. If those insurers don't have to make massive payments, they probably won't have to liquidate assets like JGBs.

    In fact, Japanese bonds have remained stable and the yen has even strengthened since the disaster. Economists have attributed this phenomenon to speculation that Japanese institutions could sell US Treasuries to raise money, and that domestic companies might repatriate money to pay for earthquake damages. Japan, the largest buyer of US debt after China, could also momentarily stop buying Treasuries while it figures out how much it needs to spend on rescue and clean up efforts.

    Second, Japan holds more than 95% of its own debt, according to Bank of Japan data. Even if foreign investors began to unload their bonds, they account for a small part of the overall market.

    So while the specter of a debt crisis hangs over Japan as much as it ever has, it's unlikely to occur in the immediate wake of the earthquake. The day of reckoning for Japan's debt problem will come when foreign markets determine the interest rates on JGBs.

    Japan's addiction to credit was fueled in large part by its ability to borrow from its own institutions and people. Now that same dynamic may shield the country from the harsh forces of the market at a time when it needs the protection the most.