The Lake Cahuilla Basin, 132 miles from downtown Los Angeles, is separated from the Gulf of California to the south by the expansive, ever-changing delta of the Colorado River. The current body of water in the lake’s southern basin, called the Salton Sea, was born in 1905, when heavy rain and snowmelt in the Colorado River drainage led to the collapse of an intake canal built for irrigation purposes just south of Yuma, Ariz. The river then poured into the sink.

The observation that the last lake and last quake were at about 1700 AD and that there have been seven earthquakes and seven lakes during the approximately past 1,000 years have led to the hypothesis that the filling or emptying of each lake triggered earthquake events by changing the pressure on the fault plane below. The new study, Weldon says, shoots down that idea.

The data show that earthquakes occurred in all scenarios: when the lake was filling, while it was full, when it was draining and even when it had long been dried up. In fact, researchers found, the last quake in about 1690 occurred when the lake was full, just before it drained.

Calculations of how long the lake would take to dry, if shut off from its Colorado River source coupled with travelers’ journals, cited in the study, actually provide witness to the lake’s disappearance. “If anything, the earthquake made the lake go away,” Weldon says.

“The most popular hypothesis has been that the filling of the lake causes an earthquake, or the draining of the lake causes a quake,” he says. “Neither can be true based on where we’ve found. There’s probably no relationship, but if you want to say there is a relationship, it could be that the quakes make or unmake the lakes.”