In 1974, residents of Sitka, Alaska were alarmed when the long-dormant volcano neighboring them, Mount Edgecumbe, suddenly began to belch out billows of black smoke. People spilled out of their homes onto the streets to gaze up at the volcano, terrified that it was active again and might soon erupt.
Luckily it turned out that man, not nature, was responsible for the smoke. A local practical joker named Porky Bickar had flown hundreds of old tires into the volcano's crater and then lit them on fire, all in a (successful) attempt to fool the city dwellers into believing that the volcano was stirring to life. According to local legend, when Mount St. Helens erupted six years later, a Sitka resident wrote to Bickar to tell him, "This time you've gone too far!"
Did you guess? The theme this week is April Fools.