Shaped like a porkchop, this quiet spring was named “Dr. Morey’s Porkchop” in 1961, but it proved unexpectedly volatile, beginning with an eruption in 1971. For the next 14 years, it occasionally erupted through its tiny vent and became known as Porkchop Geyser. In 1985, it erupted and did not stop until exploding several years later. On September 5, 1989, its narrow vent became constricted, throttling its flow of water and steam as heat and pressure intensified until it blew up, throwing rocks more than 200 feet toward eight park visitors. The visitors were not hurt, and the upended rocks visible today resulted from the small hydrothermal explosion they witnessed. Porkchop’s eruptions are now rare, sometimes years apart, and its future behavior remains uncertain.