The Cataclysm Which Split Oahu in Half; The Nu'uanu Slide

A little more than 1 million years ago, a cataclysm struck the island of Oahu, causing the island to split in half. As a little more than half of an entire shield volcano dramatically collapsed into the ocean, a towering megatsunami was generated. Today, the remnants of this event which is known as the Nu'uanu Slide can be widely seen on the northern section of Oahu, as it left behind several thousand foot tall steep cliffs.

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Sources/Citations:
[1] U.S. Geological Survey
[2] Hawaiian Volcano Observatory

0:00 Oahu's Cataclysm
1:13 Landslide Volume
2:21 2 Volcanoes
3:09 Overloaded Edifice
3:59 Conclusion

[GeologyHub]

Large volume landslides have occurred at many island shield volcanoes such as in the Canary Islands and Hawaiian Islands. However, incredibly large volume volcanic landslides are incredibly rare.

[tactiletinkerer]

Excellent! Was waiting for GeologyHub to publish this episode, being raised in HI and learning about the Nu‛uanu Landslide in the '80s. Just the sheer scale of the collapse must've been terrifying -- esp to life on the Eastern side of the Ring of Fire... can you imagine a 50-story-high wave after all the water drains out of your little idyllic bay home, 1Ma ago? 🤯

Small note on pronunciation of Hawaiian names: the Western O‛ahu mountain range is the Ko‛olau range, pronounced 'KOH-[/ʔ/ glottal stop]-oh-lau (all open vowels, as in the word 'loud'). Only use a glottal stop when the *‛okina* or rotated apostrophe's present and you'll be fine (regular apostrophe's fine for most non-academic publications imo). What many publications not sensitive to proper presentation of Hawaiian names tend to do, is omit the apostrophe altogether (like Google unfortunately) which spell it Koolau -- doesn't help those new and well-meaning to Hawaiian / Polynesian names. Thanks and keep publishing and growing the channel! It's a must watch for this GenX Maui boy geology fan 🙂👍👍

[sergiorodriguezballestero]

Blow my mind every single time I watch one of your videos!!!! Dang!!!! 🤙🏼

[duaneharnes]

I learned of this slide back in the early nineties. Sure does change one's perspective. I am so glad you covered this event, We little creatures need to understand the geology beneath, and all around us.

[bradsnider]

Mahalo nui loa for this! I asked for it a while back, and you delivered!

Such excellent timing, too! My brother, who lives in Lʻaie, is coming to visit in 2 weeks! I can’t wait to show this to him, to get to watch it together! Aloha! 🤙🏼

[cpwrx]

Great information! And for future reference, the proper pronunciation of the upper east mountain range on the Windward side of the island is pronounced Ko'olau (Ko•oh•laow). The 'okina in our language is read as a glottal stop and is technically its own letter in our alphabet. How you pronounced Waianae was perfect though!

[adriennewaterhouse]

THANK YOU!!! Also a cool tidbit, when it rains heavily enough ( which is often esp during winter like now ) we get plenty little waterfalls known as tears from Koolau

[thebarak]

Before Waianae was what we now call Ka'ena volcano, currently deep underwater towards the direction of the older island Kauai. So Ko'olau is the third volcano making up the O'ahu system. At the time of the Nu'uanu slide, Ko'olau was likely as high as today's Mauna Kea, so that also helps to visualize why the slump is so far offshore. The caldera is usually regarded as being south of Kaneohe Bay near to Maunawili, but of course it was thousands of feet higher in the air so we cannot be certain where the center was. You don't have to look far to find a more recent slump off the north shore of Molokai.

[WilliamRWarrenJr]

I was either 10 or 11 when I first saw the Nuuanu Pali Lookout. Even then (1964-66), I was blown away by the sheer cliffs and the stark contrast with the gentle slopes of the leeward side. I only recently heard about the Nuuanu slide in relation to another similar geological disaster a'building, I think Monteserrat? I always enjoyed our opportunities to visit that site. Thanks for the memories!

[bryanruss]

As you probably know there are many many of these massive landslides among pretty much all the Hawaiian islands. Can you do a video on this phenomenon as a whole and all the places around the world where volcanic islands show this occurrence all over the ocean floor. It’s fascinating.

[rh]

I was lucky enough to be stationed at MCAS Kaneohe on two separate occasions. Absolutely stunning view. I was able to see the elevated view daily as I drove through the tunnel on H3. The view from base was equally impressive. It’s tempting to keep your eyes off the road for too long when driving in that area. 👍👍👍

[S-T-E-V-E]

Mind Blowing! I love thinking about these huge destructive events in our history! Great Video! 👌

[TheJohtunnBandit]

My parents live right on the coast near kaneohe bay and it is so cool to know when I visit I will have been swimming in an ancient caldera/historic landslide.

[tolson]

I think that Molokai experienced a flank collapse like Oahu. The offshore seafloor topography north of Molokai is very similar to what we see NE of Oahu only in the case of Molokai, the blocks are parallel to the north shore of the island.

Even more interesting is that we are witnessing the formation of another major flank collapse on the southeast side of Hawaii. Note the steepness of the undersea terrain dropping 15, 000 feet in 15 miles. I believe the fissure that opened in the Leilani Estates in 2018 was a result of the south flank of the island experiencing extensional forces due to the instability of the south flank.

[HonoluluBoy]

Thank you for doing this one, I recall suggesting it a few months ago.

[richardcrabbe]

I was born, raised and still live on O'ahu. Mahalo (thanks) for your great video filled with wonderful and informative information. Keep up the great work!

[mistysowards]

I wondering these insane slides or edifice collapse events happen mostly over a long time span or kinda like the way falts constantly creep for years a few mm a day or even less. I'm surprised you didn't mention the big island of Hawaii southern segment that is currently sliding now, just a few mm a year as of now. But to have blocks the size of Manhattan transported over 20 miles means an enormous event took place suddenly. Really fascinating stuff.

[anassorbestiak]

Super interesting, what a huge event!

[MrDogfish]

Glad I found this video. I knew Oahu had a big slide, but I thought it somehow involved the west half and the east half of the island. This clears it up.

[DonzLockz]

Wow, I had no idea when I visited there in 2017. I did a bus tour around the south half of the island and have video and pics that I'll need to look at again. Thank you, Oahu is such a beautiful place now. That side of the volcano is luckily not commercialised like Honalu. I wish I knew this before but thats a good excuse to go back again. :)