Final answer:
A supply shock is when OPEC significantly alters oil production, impacting the market equilibrium.
Step-by-step explanation:
When OPEC attempts to influence the price of oil by significantly altering production, economists refer to this type of event as a supply shock. Supply shocks occur when there is a sudden change in the supply of a commodity, such as oil, that disrupts the equilibrium in the market. In the case of OPEC altering production, it can lead to a decrease or increase in the supply of oil, which can have a significant impact on the price and availability of oil in the market.