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Koa'e fault zone and the Kamakaiʻa Hills

1:44 AM · Apr 19, 2022

"Photogrammetric survey above the Koa'e fault zone and the Kamakaiʻa Hills, [Kīlauea] ... DEM (low res) processed by @stefano_volcano" ~ Joël Ruch The following is taken from USGS Volcano Watch, 2016: "Kamakaiʻa Hills: what are they and why are they there?": "The cones are the Kamakaiʻa Hills. Their Hawaiian name means "the eye of the fish," possibly because the cones, each dimpled with a cup-shaped crater, reminded early Hawaiians of the eyes on prized fish, such as ulua. The Kamakaiʻa cones are merely the largest of a series of vents, including older, more eroded cones, spatter ramparts, and large ground cracks, that spewed lava clots and blocks of older rock for short periods. Multiple eruptions have originated along this three-mile long "mini-rift" over a period spanning at least 500 years. The two largest eruptions, each probably lasting weeks to a few months, produced far-travelling flows and rootless lava shields similar to those that have grown around Kīlauea's East Rift Zone Pu‘u ‘Ō‘ō vent over the last three decades. The big Kamakaiʻa cones developed during explosive phases of the eruptions, producing fields of volcanic bombs, rubbly scoria, and spatter. The largest bombs in these ejecta beds exceed 1 m (3 ft) in diameter. Unusual eruption products at the Kamakaiʻa Hills correspond with a form of lava that has no equivalent elsewhere on Kīlauea—pasty pāhoehoe with a distinctively stretched "skin" that resembles the grain one might find on pieces of old driftwood. This lava is also chemically distinctive. Preliminary analyses of the lava indicate that at least some of it contains much more silica than ordinary Kīlauea basalt. In fact, it is similar to basaltic andesite, a type of lava abundant in the Coast Range of Oregon and northern California." (More: Volcano Watch — Kamakaiʻa Hills: what are they and why ...) --- Since this Volcano Watch was written, Kīlauea erupted into the Lower East Rift Zone where one fissure, Fissure 17, also produced an eruption with a similar andesite chemical composition.


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