Lava Delta Fissures: Unravelling the Significance of the Kilauea Volcano's 2018 Cracks

The United States Geological Survey (USGS) and the Hawaiian Volcano Observatory (HVO) continue to closely monitor Kilauea's activity, particularly in the aftermath of the significant 2018 eruption in the lower Puna region of the Hawaii Islands.

The latest episode, the 31st summit eruption, occurred on August 22-23 and lasted approximately 13 hours. However, no unusual activity has been noted along Kilauea's East Rift Zone or Southwest Rift Zone as of now.

The beach at Pohoiki Bay, a striking feature born from the 2018 eruption, is a testament to the volcano's power. Lava that fragmented when it entered the ocean was transported along the coast to the bay, creating this new coastal landscape.

Elsewhere, the lava delta near Pohoiki is experiencing new ground cracks, a phenomenon that may continue as the delta adjusts to its environment. It's worth noting that the 1960 lava delta, located nearby, consists of a solid surface atop loose submarine debris known as hyaloclastite, which is prone to subsidence and erosion. Collapses of the lava delta are likely to be relatively small, with at most a few tens of feet (several meters) slumping into the ocean.

In other news, Mauna Loa, another active volcano on the islands, is not currently erupting, with its USGS Volcano Alert Level at NORMAL.

Looking ahead, forecasting models suggest the likely window for the next Kilauea summit eruption begins late next week. Sulfur dioxide emission rates are elevated in the summit region during active eruption episodes, a sign of the volcano's activity.

Both lava deltas are exposed to the full force of the Pacific Ocean, with no other islands or a nearshore coral reef to protect them. Ninety percent of the coastline along Kilauea is less than 1,000 years old and lacks a significant fringing reef, further emphasising their vulnerability.

The USGS Volcano Alert level for Kilauea remains at WATCH, indicating that an eruption is possible within the next few days to weeks. Summit region inflation since the end of episode 31 suggests another episode is possible.

For more information, visit HVO's website or email questions to [email protected]. It's also important to note that a M3.5 earthquake was reported in the Hawaiian Islands, 11 km SE of Pahala at 30 km depth on August 27 at 12:44 p.m.

Lastly, an older lava delta nearby, formed during the 1960 eruption of Kilauea, provides evidence of what the future of the 2018 lava delta may hold. The Kilauea summit has been erupting episodically within the caldera since December 23, 2024.

Stay informed and stay safe.