FACTBOX: The world's oil shocks

(Reuters) - Oil remains within sight of a record hit in mid-June of nearly $140 a barrel -- a rise of 40 percent since the start of the year that has prompted many to suggest the world is experiencing a third "oil shock."

Earlier this month the head of the International Energy Agency Nobuo Tanaka said the world was in a third energy crisis and called for an "energy revolution" to cut demand.

The previous crises were caused by a sharp reduction in supply preceded by political turbulence and war.

This time round, booming demand from emerging Asian and Middle Eastern economies has pushed the price of oil to real-money highs even as consumption slows in the developed world.

* 1973 - The first oil shock was caused by an Arab oil embargo directed at Israel's supporters in the Arab-Israeli war: primarily the United States but also Japan, the Netherlands, Portugal and South Africa.

The price of oil quadrupled to almost $12 a barrel. Sudden inflation quickly infected the economies of other industrialised countries.

The crisis ushered in an era of oil price forecasting, encouraged conservation and the search for diversified sources of oil and furthered research and use of alternative fuels.

* 1979 - The second oil shock followed the Islamic Revolution in Iran and was keenly felt in top consumer the United States which had to ration fuel. All exports from Iran stopped, resulting in a loss of about 5 percent of overall supply and a price spike of 150 percent. Oil averaged just under $32 a barrel in 1979.

* Iran-Iraq war - Battle between the two major oil producers initially cut 4 million barrels per day from the market, or 8 percent of world demand. Oil averaged about $37 in 1980.