Could someone explain the 1998 Russian Ruble Crisis?
A shorter less technical answer is this: The Ruble was pegged to the dollar. The commodities Russia sells (incl oil) were also sold in dollars. When those commodities became cheaper due to the Asian crisis, Russia got less money for what it sold and was unable to pay its own debt. so they skipped paying on their own bonds and let the ruble float freely on the currency markets… the resulting adjustment was the drop in the Ruble. If oil goes to $20 a barrel it could happen again, but not as bad because the ruble is already down in the 30’s.
