The Hawaiians call them Pali. Scientists call them fault scarps. Most of us would call them cliffs. But by whatever name you call them, they can be deadly especially along the seacoast close to the Chain of Craters road.
These cliffs are common both around the summit calderas and close to the ocean. Those cliffs on the ocean are being constantly pounded by the surf, which continually erodes them close to their base at water level. This constant undermining is usually not visible from the top of the cliffs so tourists are unaware of their dangerous nature. But large chunks of these seaside cliffs often plunge into the ocean.
There are a few signs cautioning tourists to stay off these sharp, wet and dangerous areas but some choose to ignore these warnings at their own risk. There are few if any places to get from the top of these cliffs to the water so if one fell into the ocean it would be very difficult to rescue them. And, as you can see from the picture, beaches that a victim might use to save themselves are non-existent or very small and dangerous.
It is just smart to admire these beach-side cliffs from the road instead of up close and personal - maybe too personal!