‘On the high side’

Ki­lauea’s sum­mit lava lake rises; small tem­blors rum­ble un­der volcano

Hawaii Tribune Herald - - FRONT PAGE - By TOM CALLIS

Ki­lauea’s sum­mit lava lake is the high­est it’s been in more than a year.

The lake inside Over­look crater, which sits inside Halema‘uma‘u Crater, con­tin­u­ally rises and falls in con­cert with magma pres­sure be­low. As of Mon­day morn­ing, this cy­cle had pushed it to just 33 feet be­low the Over­look rim, mak­ing it vis­i­ble from a safe dis­tance at Jag­gar Mu­seum.

Hawai­ian Volcano Observatory spokes­woman Janet Babb said it was last that high on Jan. 4, 2017. The lava has been ris­ing since Fri­day but it’s not known how long that trend, which can quickly re­verse, will con­tinue.

“Over­all, it’s been on the high side” re­cently, Babb said, re­fer­ring to the lake level.

“With this lat­est in­fla­tion, it’s just push­ing up even higher.”

Oc­ca­sion­ally, the lake will go high enough to spill onto the floor of Halema‘uma‘u Crater. That hap­pened in Oc­to­ber 2016 and April and May 2015, Babb said.

But it’s not the only vol­canic ac­tiv­ity of note.

On April 10 and 11, HVO de­tected a swarm of small earth­quakes be­tween 5 and 10 kilo­me­ters be­low the sum­mit.

Brian Shiro, HVO seis­mol­o­gist, said that’s a re­sult of magma mov­ing through the volcano’s plumb­ing. It oc­curred at the right depth to be lo­cated within or around the lower magma cham­ber.

“It stands to rea­son that some­thing changed down deep,” he said. “I cau­tion to make a direct cor­re­la­tion there,” Shiro added, re­fer­ring to the rise in the lava lake.

He said there were 194 small tem­blors counted. Most were of mag­ni­tude-2 or smaller and were too weak to be felt.

Shiro said such swarms hap­pen ev­ery cou­ple of years, of­ten with no ap­par­ent ef­fects on erup­tion ac­tiv­ity at the sum­mit or Pu‘u ‘O‘o.

He noted there have been four such swarms in about as many months, which is unique.

HVO re­ported Mon­day a slight in­crease in seis­mic­ity in the Up­per East Rift Zone overnight.

Cour­tesy of HAWAI­IAN VOLCANO OBSERVATORY

Ki­lauea’s sum­mit lava lake as of Sun­day.

BABB

SHIRO

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