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Report on Kilauea (United States) — July 1993


Kilauea

Bulletin of the Global Volcanism Network, vol. 18, no. 7 (July 1993)
Managing Editor: Edward Venzke.

Kilauea (United States) New lava breakout on the Kamoamoa delta reaches the ocean

Please cite this report as:

Global Volcanism Program, 1993. Report on Kilauea (United States) (Venzke, E., ed.). Bulletin of the Global Volcanism Network, 18:7. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199307-332010



Kilauea

United States

19.421°N, 155.287°W; summit elev. 1222 m

All times are local (unless otherwise noted)


The . . . eruption continued in July with lava entering the ocean on the E and W sides of the Kamoamoa delta. The W Kamoamoa . . . flow built small benches below the old sea cliff that were soon broken apart by the high surf. Activity at this new flow declined throughout July. Lava entered the ocean along a 160-m-wide front on the E side of the Kamoamoa delta through most of the month. New land continued to be very unstable in this area. On 3 July, most of the lower bench at the E entry collapsed (an estimated area of 20 x 150 m), leaving behind a sliver of bench still attached to the delta. Lava flows quickly built a new bench extending ~35 m into the ocean, and two new littoral cones formed on the bench surface.

Lava tubes drained on 23 July and lava stopped pouring into the ocean . . . . The eruption resumed the next day as lava reoccupied the E-51 tube. Two small flows broke out of the tube; however, most of the erupted material traveled within the tube to the coastal plain. A large pahoehoe sheet-flow broke out just below a fault scarp and spread out over older Kamoamoa flows (figure 92). One part of the flow descended the W side of the Kamoamoa flow and entered the ocean on 27 July. Another finger advanced down the E side of the Kamoamoa flow and entered the ocean on 28 July. Isolated portions of Chain of Craters Road were covered on both sides of the Kamoamoa flow. Lava entered the ocean along wide fronts and explosive activity was rare. However, one large explosion on 28 July blew lithic blocks inland of the W entry point.

Figure (see Caption) Figure 92. Recent lava flows (November 1992-July 1993) from Kīlauea in the Kamoamoa delta area, July 1993. The new lava flow broke out of the tube on 24 July; lava reached the W Kamoamoa entry on 27 July, and the E entry became active on 28 July. Courtesy of T. Mattox.

A team of French and Swiss geologists who spent the night of 10-11 July at the summit of Pu`u `O`o observed the . . . lava pond for a number of hours. Activity was intense throughout the night, with the level of lava fluctuating 1-2 m. Bubbling was localized in the S and SE parts of the pond. At one point, a large collapse of the inner SSE crater wall produced a wave surge across the lava pond. Waves were several meters high, and covered the entire surface for several seconds. Other smaller landslides occurred during the night, showing the instability of the inner crater walls. The lava pond remained active throughout the month, with the surface fluctuating between 74 and 81 m below the crater rim.

Eruption tremor along the East rift zone continued in July at a relatively steady amplitude of 2x background level. Shallow, long-period microearthquake counts were slightly above average in the first half of the month, but were low later in the month, except for 22-23 July. Counts of short-period events were low beneath the summit and about average along the East rift zone.

Geological Summary. Kilauea overlaps the E flank of the massive Mauna Loa shield volcano in the island of Hawaii. Eruptions are prominent in Polynesian legends; written documentation since 1820 records frequent summit and flank lava flow eruptions interspersed with periods of long-term lava lake activity at Halemaumau crater in the summit caldera until 1924. The 3 x 5 km caldera was formed in several stages about 1,500 years ago and during the 18th century; eruptions have also originated from the lengthy East and Southwest rift zones, which extend to the ocean in both directions. About 90% of the surface of the basaltic shield volcano is formed of lava flows less than about 1,100 years old; 70% of the surface is younger than 600 years. The long-term eruption from the East rift zone between 1983 and 2018 produced lava flows covering more than 100 km2, destroyed hundreds of houses, and added new coastline.

Information Contacts: T. Mattox and P. Okubo, HVO; H. Gaudru, SVE, Switzerland.