Japan's economic growth surged in July-September as efforts to restore supply chains and make up for lost output in the wake of the March disasters helped Japan to its first expansion in four quarters. The economy's first growth since the March earthquake, tsunami and subsequent nuclear crisis came ascompanies such as automakers ramped up production. The world's third-biggest economy grew by an annualised 6.0 percent in the July-September quarter, preliminary data showed Monday, the fastest pace since January-March 2010. The result was largely in line with market expectations. On a quarterly basis, gross domestic product grew 1.5 percent in July-September, the data showed. Japanese GDP data is subject to constant revision, however. Improving exports were the biggest contributor to GDP growth in the third quarter, a government official said, followed by private consumption. On a quarterly basis, exports were 6.2 percent higher, or up 27.4 percent on an annualised basis. Private consumption gained a quarterly 1.0 percent, or 3.9 percent annualised. Analysts warned that the third quarter surge could be a one-off due to the size of the drop after the earthquake, while a strong yen and a downturn in overseas export markets has clouded the outlook for Japan's fragile recovery. The disasters left 20,000 people dead or missing, devastated large areas of the northeast and sparked a nuclear crisis at the Fukushima nuclear plant. The damage and devastation brought by the tsunami also shattered crucial component supply chains, forcing companies to shut down factories, slowing the nation's output and exports as the economy tipped into recession. While Japan's producers hve raced to restore output more quickly than expected, there are concerns that effort could be undermined by a strong yen that erodes repatriated profits, as demand wanes amid a global economic slowdown. The yen has recently hit post-World War II highs versus the dollar amid heightened market volatility, despite efforts by Japanese authorities to stage yen-weakening market interventions.