The Keaiwa or 1823 Lava Flow from Kilauea Volcano, Hawaii

Abstract

The oldest historic lava flow of Kilauea is that of 1823. Lava issued from the Great Crack, on Kilauea's lower southwest rift zone, over a total length of 6 mi, very unusual for an Hawaiian eruption. It spread out as a flow which, in places, is only a few inches thick. There is a notable absence of cinder or driblet cones. Lava balls along the walls of the crack were formed by accretion around clots of cooled lava which fell back into the vent. The lower slopes of "lava-plastered cones," prehistoric vents, are covered with 1823 lava, which was dammed just behind them. Another older cone has lava splash 34 ft above the present level of the flow. [These observations suggest an unusually rapid eruption and flow rate.] Two phreatic explosions occurred just after the eruption. Phreatic explosion debris contains a few fragments of brecciated shells and coral, the first accidental ejecta ever found on Kilauea. Stearns reviews the confusion regarding the location of the 1823 lava and gives a corrected map showing the proper positions of the 1823, 1868, 1920, and prehistoric Kamooalii flow. He concludes that a coral reef underlies the area, signifying that the shoreline was extended by the prehistoric flows underlying the 1823 lava. Stearns states that a re-entrant in the south coastline of Kilauea is due to downfaulting in the submarine section of the volcano. [Stearns' idea is supported by recent undersea surveys. The retention of the re-entrant as a permanent feature, defined by more recent lava entry into the ocean on either side, may be due to onshore development of the Koae fault system. Once developed, the Koae grabens have prevented lava from Kilauea summit or the upper parts of the rift zones from reaching the coast along the area presently defined as a re-entrant. See also J.B. Stone, 1926a.]