UPDATE 10-Oil falls after Japan quake, tsunami

                                
 * Japan quake shuts some refineries, nuclear plants
                                
 * Saudi police flood streets to deter protests
                                
 * Coming up: CFTC positions data 3:30 p.m. EST (2030 GMT)
 (Recasts, updates prices and market activity, changes byline
and moves dateline from LONDON)
                                
 By Robert Gibbons
                                
 NEW YORK, March 11 (Reuters) - Oil prices fell on Friday
after a massive earthquake shook Japan, the world's
third-largest oil consumer, sending a tsunami sweeping across
the Pacific Ocean and pushing U.S. crude prices below $100.
                                
 As the implications for oil demand in the region affected
by the earthquake received attention, investors also monitored
a planned day of demonstrations in top oil exporter Saudi
Arabia and the violence in Libya, where oil exports have been
disrupted.
                                
 Brent crude futures for April delivery <LCOc1> fell $1.16
to $114.27 a barrel at 12:03 p.m. EST (1703 GMT), having fallen
as low as $112.25.
                                
 U.S. crude futures for April delivery <CLc1> fell $1.80 to
$100.90 a barrel, having briefly traded at $99.01.
                                
 With the earthquake shutting some refineries in Japan,
refiner profit margins for gasoline in the United States
<RB-CL=R> jumped to $24.96 from $22.76 on Thursday.
                                
 The heating oil crack spread <CL-HO=R> rose to $26.43 a
barrel from $25.18 on Thursday.
                                
 Brent's premium to the U.S. benchmark West Texas
Intermediate crude <CL-LCO1=R> rose 63 cents to $13.18 a
barrel, after falling below $8 this week and reaching a record
above $17 last week.
                                
 Metals and soft commodities also fell. [ID:nLDE72A149]
                                
 Japan was hit by a magnitude 8.9 earthquake, the largest
since observations began in the late 19th century.
[ID:nL3E7EB0MF]
                                
 While the full extend of damage was still being assessed,
analysts said the images and reports so far did not suggest a
major economic and financial disaster. [ID:nN11294567]
                                
 "Crude oil futures have fallen sharply as a sizable portion
of Japan's oil refinery capacity has been shut due to the
earthquake and tsunami. Data from China showing higher
inflation also added pressure," said Joe Posillico, broker at
MF Global in New York.
                                
 Posillico said the question going forward would be, "how
long Japan's crude oil demand will be affected."
                                
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 Japan quake tears through commodity, energy sectors:
                                
                                    [ID:nL3E7EB1UN]
                                
 Graphics showing:
                                
 Middle East unrest          http://r.reuters.com/nym77r
                                
 Libya unrest                http://link.reuters.com/dew48r
                                
 Main Saudi oil region       http://link.reuters.com/gew48r
                                
 FACTBOX on Libya's oil sector              [ID:nLDE7292FC]
                                
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 (Additional reporting by Gene Ramos and Janet McGurty in New
York, Ikuko Kurahone in London and Alejandro Barbajosa in
Singapore; Editing by Walter Bagley)