HILO — Kilauea’s summit was rocked by earthquakes Wednesday afternoon as its churning lava lake put on a show for visitors in Hawaii Volcanoes National Park.
A 3.8-magnitude quake struck at a shallow depth of 1.8 miles at 12:17 p.m. It occurred just 3.2 miles southeast of the summit.
That was followed by a 3.5-magnitude aftershock at 1:12 p.m.
At the same time, spattering from the lava lake at Halemaumau crater was visible as the volcano inflated from an influx of magma below.
HVO spokeswoman Janet Babb said the quakes had no immediate effect on the lake, which came into view Tuesday.
The lava lake was 66 feet below the crater rim as of Wednesday morning.
That’s the highest it has been since May 2015 when lava spilled onto floor of Overlook crater.
Babb said the earthquakes occurred in Kilauea’s upper east rift zone, where magma travels from the summit’s chamber to the Puu Oo vent. But it may not have been caused by a surge of magma moving through the system.
That would be indicated by additional earthquakes down the rift zone.
“When this happens, we do immediately start watching it,” she said. “And we look for a progression of earthquakes and shallowing of subsequent earthquakes, and we didn’t see either.”
Brian Shiro, HVO’s seismic network manager, said the quakes likely were a result of movement along faults rather than magma.
“I would be inclined to think this is more of a tectonic type of thing,” he said.
Babb said the volcano was going through an inflationary period when magma builds up in its chamber, prompting the summit to bulge outward. The chamber is located a few miles below the summit.
These subtle changes are detected only with sensitive equipment.
Magma inflation does place more stress on the volcano, but the quakes were likely too far away from the summit for there to be a direct connection, Shiro said.
Babb said it was unclear Wednesday if the inflationary trend was to continue.
If the volcano enters a deflationary phase, the lava lake could retreat out of view.
The summit lava lake is the easiest way to see lava, but it’s not the only spot in Hawaii Volcanoes National Park with molten rock.
The 61g lava flow from Puu Oo continues to be active along the coast. An ocean entry stretches across about 1 kilometer of coastline.