Slid Sliding Away

Steve's picture

I’m not from the “Show Me” state, but like those folks, I tend to believe it when I see it. Earth scientists like myself have some advantage in seeing because we “dig in the dirt”. From what we find there we can envision geological happenings over scales of space and time that others can’t fathom. 

Back in the 1960’s sonar mapping around Hawaii revealed what, for all the world, looked like debris fields from giant landslides trailing from the Islands for 50 miles or more. For a long time, scientists remained skeptical about a landslide explanation for these deposits because of their immense volume.  Just one would be as if ground the size of San Francisco vanished into the ocean --- and there were dozens of slides branching from all the Islands.  As the 1970’s and 1980’s past however, no one could offer a plausible explanation for the debris other than the obvious one. It seemed inescapable that many times during their youth, the volcanoes of Hawaii rose in height, expanded in width and became unstable. In a matter of minutes, hundreds of cubic miles of material then broke off their flanks and tumbled down at 200 miles per hour.

Maybe so, I thought when I heard this tale years ago, but I’ll believe it when I see it. Then in November 2000, a set of GPS geodetic stations confirmed that a huge chunk of Kilauea Volcano had suddenly moved 10 cm toward the sea in one night. Sure enough, a 10 or 15 mile-wide slice of Hawaii was slip sliding away. A precursor to the next colossal landslide? That night thankfully, another wonderful piece of Island real estate did not become a corpse laid out on the sea bed. I had seen sonar images of those pre-historic slides and now I witnessed half a volcano lurch all at once. I’m not from the Show Me State, but I believed.

I put together this YouTube movie of a Kilauea flank failure and mega tsunami. Likely you and I will never see the real thing, but physics based simulations count as next best.

Steven N. Ward   Santa Cruz

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