The idea: take “Waiting for the other shoe to drop,” normally used when a damaging bit of news has been released and another damaging bit is expected, and apply it to a politician who is suffering a whole series of damaging revelations. It’s typical for big scandals to go thru a phase like that, when the hits just keep on coming, headline after headline, and reporters love the shoe-drop figure of speech. But nothing about shoe stores in earthquakes; I even checked Google.