Nonchaotic collapse at funnel calderas; gravity study of the ring fractures at Guayabo Caldera, Costa Rica

The Guayabo caldera, northern Costa Rica, has an overall funnel-shaped morphology, but gravity data supported by detailed borehole stratigraphy demonstrate that the collapse mechanism does not conform to the so-called chaotic models proposed for such calderas. Rather, an inner block collapsed across steep ring faults, delineated by a central gravity minimum. This initial subsidence was succeeded by multistage collapse across outer arcuate faults that are responsible for the currently defined caldera rim.