Kilauea's East Rift Zone Research Articles

Bryophytes and Lichens of the Puhimau Geothermal Area, Hawaii Volcanoes National Park

The vegetation of the Puhimau geothermal area was compared with that of the surrounding ecosystem. Very few species of the surrounding area were found with any abundance in the geothermal area. The center of the geothermal area is almost barren. Pockets of vegetation dominated by the endemic moss Campylopus praemorsus (C. Muell.) Jaeg. are throughout the central area. The only other temperature-tolerant species present is Portulaca sclerocarpa Gray. Cladonia oceanica Vain. is commonly found growing epiphytically on the moss away from the high temperatures. The central zone is surrounded by an Andropogon-dominated grassland in which both C. praemorsus and C. oceanica are commonly fertile. No lichens exhibited any tolerance of high temperatures. The Puhimau geothermal area, often referred to locally as the Puhimau Hot Spot, is located on the east rift zone of Kilauea volcano on the island of Hawaii. The area was formed in the winter of 1937-38 when magma came close to the surface and resulted in hydrothermal activity rather than the usual destruction associated with lava flows. The original Metrosideros forest was killed but not burned. The steam vents formed were confined principally to the bases of tree trunks. Some of these trunks are still present in the area and support a distinctive fumarolic community. Although sulphurous gases are normally emitted from fumaroles during the degassing of subterranean lava, no sulphur dioxide or hydrogen sulphide gas has been recorded from the vents in the Puhimau thermal area in recent years (Siegel & Siegel 1979). Recent subterranean volcanic activity in the area resulted in a short (less than 48 hours) emission of SO2. Fosberg and Lamoureux (1966) briefly described the vegetation of two areas of the east rift zone of Kilauea in Hawaii Volcanoes National Park in which there was hydrothermal activity. One of these areas has since been destroyed in the formation of Mauna Ulu. In these areas, they recorded Cladonia cf. cristatella (= C. oceanica Vain.), C. cf. rangi- ferina (= C. skottsbergii Magn.), and Racomitrium (presumably R. lanuginosum var. pruinosum Wils.). Kappen (1973), citing a personal communication from Mueller-Dom- bois, confirmed the presence of these lichens scattered on volcanic soils. Ground tem- peratures from 48 to 89?C have been recorded in both areas, suggesting that all species growing there were remarkably heat tolerant. Although lichens (Lange 1953; Kappen 1973) and mosses (Noerr 1974) are very tolerant of high temperatures when desiccated, when hydrated their tolerance is significantly di- minished. Some mosses are tolerant of temperatures up to 50'C (Noerr 1974) whereas lichens can remain active only up to about 25-30?C (Lange 1965).

Hydrology and Chemistry of Ground Water a in Puna, Hawaiia

ABSTRACTPresented is an analysis of the hydrology and chemistry of the ground water of the Puna District, Hawaii, based on data from 16 drilled wells, ten test wells, two shafts and four exploratory thermal wells. Ground water occurs as (1) perched water located north of Mountain View; (2) dike water located along the east rift zone of Kilauea, and (3) basal water occurring throughout most of the district, except where dike water is present. The east rift zone serves as a barrier to ground‐water movement, as demonstrated by the difference in basal water‐table levels on the two sides of the rift zone. Salinity and temperature of the basal ground water varies greatly north and south of the rift zone due to differences in precipitation, sea‐water intrusion, volcanic activity, flow rates, permeability, and discharge.Basal ground‐water type is predominantly sodium chloride. Water samples taken from thermal test well no. 3 showed dissolved silica values two to three times higher than the 49 mg/l average for the rest of the island. Hydrologic and geologic conditions in and around Kilauea's east rift zone support the possibility of accumulations of superheated ground water. The mixing of waters of different composition at depth proved to be the most difficult problem encountered in estimating deep groundwater temperatures.

Finite element modeling of surface deformation associated with volcanism

Theoretical analyses of observed vertical and horizontal ground surface deformations near active volcanoes, particularly on Kilauea volcano in Hawaii, have led to useful estimates of the location and shape of subsurface magma reservoirs. One of the major shortcomings of the various existing elastic models is that they have very similar near-field vertical deformations and they do not explain observed differences between vertical and horizontal deformations. Finite element models appear to offer better fits between observed and computed data. Deformations were computed for idealized magma reservoirs of various shapes: spheres, horizontal lenses, vertical plugs, sills, and dikes of various inclinations. The measured surface deformations from the summit magma reservoir of Kilauea can be approximated by a group of vertical plugs whose tops come within 1 km of the surface; surface deformation of the lower east rift zone of Kilauea appears best explained as being produced by increased magma pressure in a 45° south-dipping dike whose top is about 1 km below the surface.

Some aspects of the geochemistry of F, Fe and Mn in coastal waters and in fresh-water springs on the southeast coast of Hawaii

Possible inputs of fluoride, iron, and manganese into coastal waters and fresh-water springs on the southeast coast of Hawaii by the erupting Kilauea volcano were investigated. Samples were obtained in 1969 (quiet Kilauea) and in 1970 (moderate Kilauea eruption). Water samples taken near young submarine volcanoes on the submerged east rift zone of Kilauea and from fresh-water springs in the same area were not influenced by Kilauea activity. Leaching of fresh Kilauea pumice by fresh water and sea water at 25°C produced increases of fluoride, iron, and manganese in the water samples. The total amount removed by leaching decreased rapidly with time for fluoride and manganese; iron was removed more easily. With respect to these ions it appears that submarine volcanism will not affect nearby sea water very much in the periods between eruptions. The fresh-water springs in Hawaii show typical baseline values for the elements analyzed. These was no detectable influence of moderate eruption of Kilauea on these springs, or on rain and river water upwind of the eruption. The fluoride content of the underground water was close to 0.8 p.p.m., well within the optimum range commonly maintained artificially (0.8 to 1.0 p.p.m.) in potable water supplies elsewhere.

The 1959 and 1960 eruptions of Kilauea volcano, Hawaii, and the construction of walls to restrict the spread of the lava flows

A summit eruption of Kilauea volcano took place in Kilauea Iki crater, immediately adjacent to Kilauea caldera, from November 14 to December 20, 1959. Approximately 61 million cubic meters of lava was poured into the crater during 16 short eruptive episodes. Following each of the later episodes nearly as much lava drained back into the vent as had been poured out. On January 13, 1960, eruption commenced on the east rift zone of Kilauea about 40 kilometers east of the caldera. This eruption continued until February 19, liberating 113 million cubic meters of lava, and burying approximately 5.6 square kilometers of land surface, including much agricultural land and most of the village of Kapoho. Several walls were built, to try to prevent or lessen the southward encroachment of the lava. These walls were dams, impounding the lava, not diversion barriers. Lava overflowed the dams, but it is believed that the amount of southward spreading of the lava was sufficiently reduced to more than justify their construction; and it was demonstrated that such walls, properly constructed, will adequately withstand the thrust of even thick lava flows of the type characteristic of Hawaiian eruptions.