An 18-year-old man from Maine died Tuesday on a beach near Toms River, N.J., when the hole he was digging in the sand collapsed, the Asbury Park Press reported earlier this week.
A similar death occurred in 2017 in Ocean City, Maryland, when a woman from Plano, Texas, was found buried in a hole on the beach. Ashley O’Connor died of asphyxiation, according to police.
The deaths highlight the dangers of what seems like an innocent beach activity. Holes dug in the sand can collapse, quickly turning a trip to the beach into a tragedy.
Why is digging on the beach dangerous?
Holes on beaches — and their tendency to collapse — are far more dangerous than they appear at first glance.
A hole dug on a beach of sand reacts differently than a hole dug in a farm field, explains Stephen Van Ryswick, chief of the Coastal and Environmental Geology Program at the Maryland Geological Survey.
What makes holes in the sand so prone to falling in on themselves, or “slumping,” has to do with their low “angle of repose,” Van Ryswick said.
An angle of repose is the maximum angle an object can rest on an incline without sliding down. A rock, for example, would have a 90-degree angle of repose, meaning that its sides can be straight up off the ground. Beach sand, however, would have an angle of repose closer to 30 degrees, he said.
A grain of sand that reaches the beach has tumbled far through a marine environment, Van Ryswick said, making it round. All those grains on the beach add up to a wide expanse of tiny marbles.
“Think of it like a sandcastle, where if you add a little water to the sand, you can achieve even a 90-degree angle,” he said. “The water holds it together. However, too much water is going to liquify it. If you add a bucket of water to that castle, it’s all going to slump away.”
Holes are typically dug into the beach when the sand is moist, in a zone where the tide has recently receded. As the sand dries, its structural integrity gets weaker. And when disturbed — by a person or other vibrations — it can collapse suddenly.
If someone falls into that hole, it can quickly prove deadly.
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What happens when sand collapses?
The risk with a sand collapse is similar to drowning in a liquid: oxygen deprivation leads to cardiac arrest and organ damage. The brain is particularly vulnerable, said Dr. Brian Delligatti, a physician and assistant medical director at the Peninsula Regional Medical Center emergency room.
“With drowning, you can inhale water and, to a lesser degree, sand particles,” Delligatti said. “They’re really very similar. The latter is almost like drowning in sand, essentially the same.”
After a few minutes without oxygen, Delligatti said, a victim would lose consciousness. The heart rate would drop, then stop. At that point, the victim would be without oxygen to his or her brain.
“It’s hard to say for certain, and it can vary from patient to patient, but within fewer than 10 minutes you’re in serious, serious risk of death,” he said.
Emergency responders must work fast, Delligatti said, because inhaling sand blocks air flow.
The first step would be a breathing tube and IV fluids. If that doesn’t work, experts would insert a tiny camera via a breathing tube directly into the patient’s airway to help a pulmonologist determine if sand needs to be washed out, he said.
If sand or swelling in the lungs still prevents oxygen from entering, the final step would be an advanced procedure in which the blood would be passed out of the body and through a machine –– bypassing the lungs, to provide oxygen to the patient.
The weight of sand makes sand collapses even more dangerous.
According to the U.S. Natural Resources Conservation Service, sand weighs about 100 to 112 pounds per cubic foot. By comparison, a cubic foot of water (roughly 7.5 gallons) weighs about 62 pounds.
Each cubic foot of sand on a victim’s torso is the equivalent of a 13- to 15-year-old boy standing on the victim’s chest.
“Just from a mechanical standpoint, the muscles of the chest wall might not be able to overcome the pressure and expand to allow the patient to breath,” Delligatti said.
“That’s a complication that’s actually not present in drowning, and one that can really lessen the time a victim has before rescue is an absolute necessity.”
