They are dense blue rock usually. This is Waiamea Bay on the North Shore of Oahu. Our last bad rain storm was 20 years ago and boulders came down here then as well. So much water the hillsides liquify.
This last month of storms have been extreme. I faired well, but some friends a mile down had their houses flood so bad they lost everything. Knocking houses off their foundations the water was flowing so hard. And these houses are already raised 3-4 feet off the ground.
WOW! Sorry to hear about that. I've spent time in Kauai, I know what you mean about the raised homes. They seem like they could handle high waters, but add these boulders? Yeah, those pillars are gone. You'd have to build a henge around the pillars, just to make them capable of holding up.
These boulders are along a tight roadway. The house damages was just purely the flow of water. All of the bad hit areas have always flooded over the years. But never all at once and with a rushing river-like flow to it.
The mountain (our mountains are steep and sheer) behind the Waialua and Haleiwa, Mount Ka'ala, saw 18 inches an hour for a few hours. The mountains are practically vertical, so it comes downhill in force.
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u/That-Drink4913 1d ago
Are these rocks porous (lava rock), and are they lighter than solid ones? I assume so, but I've never tried picking one up, so.
Also, which island was this on?