* Euro zone hopes, Google earnings help
* Turnover lowest this year as investors remain cautious
* Olympus shares continue plunge after CEO firing
* Exporters continue rising from early-Oct lows
* Nikkei looks set to face Ichimoku cloud test
By Hideyuki Sano
TOKYO, Oct 17 (Reuters) - The Nikkei average rose to a six-week high on Monday, helped by hopes for corporate earnings and expectations that Europe will come up with a plan to contain its debt crisis, though some market players expect the rally to run out of steam soon.
Shares in Olympus plunged for a second day as the shock dismissal of its CEO widened into corporate governance concerns. The stock has lost 37 percent since Thursday's close, wiping out $3.2 billion in market value from the Japanese precision instrument and camera maker.
Caution over the outcome of the European Union summit on Sunday, where European leaders are under huge pressure to present a plan that will decisively address the sovereign debt crisis, could cap the market later in the week.
"Global stocks and commodity prices have rallied in the past week on hopes of policy steps. But if you look at interbank money markets, tension remains high. There is the risk of disappointment," said Hideyuki Ishiguro, assistant manager of investment strategy at Okasan Securities.
The Nikkei added 1.5 percent to 8,879.60 -- its best finish since Sept. 2, while the broader Topix index gained 1.8 percent to 761.88.
But in a sign of investor caution, turnover for the Tokyo Stock Exchange's main board was 891 billion yen , its lowest since late December.
On technical charts, the Nikkei looks set to face resistance from the bottom of the Ichimoku cloud, which is around 9,010 and which will gradually fall to 8,822 by Friday.
If the Nikkei breaks above the cloud bottom, that would send strong bull sign, and could open way for a test of its Sept. 1 high near 9,100.
"I'm not that pessimistic. I think the debt crisis is coming to a climax. The Nikkei will likely pierce the cloud this week," said Hisashi Kuroda, portfolio manager at Meiji Yasuda Asset Management.
Before the weekend EU Summit, the market will be also looking to U.S. corporate earnings after solid results from Google Inc helped lift U.S. shares on Friday.
This week's U.S. results include those from Goldman Sachs , Bank of America and Apple Inc .
Olympus fell 24 percent at 1,555 yen with volume jumping to more than 30 times the company's daily average before the firing of its president. Its turnover accounted for nearly 10 percent of trade in the TSE's first section.
Many brokerages have cut their rating on the stock to "hold" or "neutral" from "buy" or "outperform".
The British former chief executive of the camera and endoscope maker said in a Financial Times interview he was fired for probing payments relating to acquisitions made by the company before he joined the board.
"The shocking developments at Olympus do not seem to be affecting broader market sentiment, as investors cautiously buy back other Japanese shares as European worries fade," said Fujio Ando, senior managing director at Chibagin Asset Management.
Among exporters, Komatsu and Sony Corp were among those continuing to post strong gains after falling to dramatic lows earlier this month on fears that Europe's woes would spread to the global financial system and have a wide impact on growth.
Sony shares added 5.0 percent to 1,607 yen, and have now gained more than 17 percent since hitting a 25-year low of 1,370 on Oct. 4.
Komatsu rose 2.9 percent to 1,783 yen, and is now up 23 percent from 1,449 yen, a two-year low marked on Oct. 5.
Some 1.45 billion shares changed hands on the Tokyo Stock Exchange's main board, about 30 percent below this year's average. (Editing by Edwina Gibbs)