USGS examines potential areas threatened in the case of a lava flow blockage

PUNA, HAWAII (HawaiiNewsNow) - If a lava flow gets blocked, it may redirect to another location. And a map released by the USGS on Friday examines the potential threats of such an event.

In a report released Friday, the agency estimates future potential flow paths by looking at three areas along the current fissure no. 8 flow. These are labeled A, B, and C on the map.

A digital elevation model was used to show potential drainage areas where fluids could descend in the case of a lava flow blockage. These drainage areas are referred to as lavasheds by the agency.

The USGS only considered flows to the north of the lava flow because residents to the south have been evacuated while residents to the north have not been evacuated.

Upper channel (A – B) 

Any major flow caused by a breach of the west wall of the channel between the vent (A) and the intersection Pohoiki Road and Highway 132 (B) is likely to advance northeast into lavashed 1, hugging the northeast edge of the existing flow. Beyond Highway 132, the flow may enter lavashed 2 and become captured by steepest descent lines that pass along the eastern boundary of the Nanawale Estates subdivision (along Road A and possibly Seaview Road). If the flow continues to advance, it will ultimately cross Railroad Avenue and Government Beach Road, enter lavashed 3, and reach the ocean between 1.3 and 2.3 km southeast of Kahakai Boulevard. If the flow enters lavashed 2 and stalls, subsequent lava flows advancing along the west side of the stalled flow could enter lavashed 4 in Nanawale Estates subdivision and ultimately reach the coast slightly closer to the Hawaiian Beaches and Hawaiian Shores subdivisions.

Middle channel (B – C)   

The fissure 8 channel becomes braided northeast of B, with narrower sections that could form choke points. If one of the narrower sections becomes blocked by large collapse fragments from the channel wall or spatter cone, lava could be diverted out of the channel. If, in this scenario, part of the channel is redirected to the north, lava could feed into lavasheds 5 or 6 and threaten homes and infrastructure in the Noni Farms area, Railroad Ave., Papaya Farms Rd., and Government Beach Rd. before entering the ocean between Kalamanu and the northern edge of the 1960 lava flow.

Lower channel (below C) 

This channel has been unstable in the area of Kapoho Crater (C) and beyond to the ocean. Most recently on July 9-10, a channel overflow in the area northwest of Kapoho Crater created a new lobe that advanced south along the west margin of the existing flow and entered the ocean on July 12 destroying a school and a beach park; however, the previous flow to the northeast continued to ooze lava into the ocean along its entire front. Although not fed by any surface flow, the earlier flow north and east of Kapoho Crater to the ocean is still oozing lava into the ocean from its front and could potentially thicken and widen beyond the current flow margins as it has in the past several weeks. Flows advancing from a breach in the northeast side of the channel near Kapoho Crater may enter lavasheds 7 or 8 and again threaten the the handful of remaining structures in the Kapoho Ag Lots and Beach Lots, structures built on the eastern section of the 1960 lava flow, and the Cape Kumukahi Lighthouse.

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