Pit crater

In these cases, the craters may merge into a linear alignment and are commonly found along extensional structures such as fractures, fissures and graben.

[9] A newly formed pit crater has steep overhanging sides and is shaped inside like an inverted cone, growing wider closer to the bottom.

Over time the overhangs fall into the pit and the crater fills with talus from the collapsing sides and roof.

[7][8] While pit craters and calderas form through similar processes, the former term is usually reserved for smaller features of a mile or less in diameter.

The modern Halema'uma'u Shield began growing and then collapsed into a deep funnel-shaped pit.

In 1924 the lava lake emptied when the walls of the crater cracked and collapsed and filled with water that turned to steam.

[10] Devil's Throat (pictured at right) is another good Hawaiian example of a pit crater, especially since we were able to observe its formation through collapse over time.