* Markets await Slovak vote on euro zone debt plan
* ECB's Trichet warns of systemic risk from debt crisis
* U.S. weekly crude stocks likely up on higher imports (Recasts, updates prices and market activity, changes dateline, previously LONDON, and changes by-line)
By Gene Ramos
NEW YORK, Oct 11 (Reuters) - Brent crude oil futures surged to nearly $111 a barrel on Tuesday, rising for the fifth straight session as investor optimism ahead of earnings season lifted markets.
Brent crude's 11 percent, five-day gain was the biggest since August 2009 and marks a sharp rebound from the eight-month low close below $100 just a week ago.
Crude futures fell sharply earlier on worries over the health of Europe's economy as its top financial watchdog said the euro zone's sovereign debt crisis threatened global economic stability.
By 12:45 p.m. EDT (1645 GMT), Brent crude for November
delivery
U.S. November crude
"It looks like the stock market turned higher and crude is following it," said Mark Waggoner, president at Excel Futures in Bend, Oregon.
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For a graphic on Brent's five-day gains: http://graphics.thomsonreuters.com/gfx/MR_20111110120149.jpg
For a 24-hour technical outlook on Brent:
http://graphics.thomsonreuters.com/WT1/20111110082525.jpg
For a 24-hour technical outlook on WTI:
http://graphics.thomsonreuters.com/WT1/20111110075735.jpg
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^> (Additional reporting by Robert Gibbons in New York; Christopher Johnson in London; Florence Tan in Singapore; Editing by Alden Bentley)