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Research about Hawaii

Source-linked reports with geographic coverage including Hawaii.

At least 1,135 records · Page 63Linked to original sources
USGS1974

Scientists probe Earth’s secrets at the Hawaiian Volcano Observatory

The Hawaiian Volcano Observatory (HVO) sits on the edge of Kilauea Caldera at the summit of Kilauea Volcao, one of the five volcanoes on the island of Hawaii, the largest island in the Hawaiian Islands chain. Of the five, only Kilauea and Mauna Loa have been active in the past 100 years. Before its last eruption in June 1950, Mauna Loa had erupted more frequently and copiously than Kilauea, but since then only Kilauea has been active.

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USGS1974

Calculated volumes of individual shield volcanoes along the Hawaiian-Emperor chain

Volume was calculated for the 107 individual volcanic shields along the Hawaiian Ridge Emperor Seamounts chain to help fulfill the need for volume data essential to determining eruption rates, fraction of mantle melted, and other parameters. Boundaries used were based principally upon location of rift zones related to each shield. Volcanic loci shown are modified from an earlier map to accommodate changes in bathymetry. Total volumes calculated for the Emperor and Hawaiian chains are 336.3 X 10 3 km 3 and 744.9 X 10 3 km 3

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USGS1973

Kilauea Volcano, Hawaii: A search for the volcanomagnetic effect

Brief excursions of magnetic field differences between a base station and two satellite station magnetometers show only slight correlation with ground tilt at Kilauea Volcano. This result suggests that only transient, localized stresses occur during prolonged periods of deformation and that the volcano can support no large-scale pattern of shear stresses.

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USGS1973

Mantle convection and volcanic periodicity in the pacific; Evidence from Hawaii

The thermal-feedback theory of mantle melting proposed by Shaw in 1969 is found to be quantitatively consistent with data pertaining to the evolution of the Hawaiian Ridge. Applicable rate factors are estimated from relations between lava volumes and position along the ridge given in this paper and the radio-metric age distributions given by Jackson and others in 1972. Rate curves derived from these data provide a new method of age extrapolation or interpolation; results indicate that previous methods used to estimate the age of the Hawaiian-Emperor Bend are in error. No definite age is established, but calculations suggest an age greater than 50 m.y. Much more extensive radiometric data are required to define kinematic relations between the Hawaiian Ridge and Emperor Seamount chain. It appears to be firmly established from the work of Jackson and others and from the present study that the evolution of the Hawaiian Ridge has been episodic, with episodes of several different time scales. Average growth rates of the entire ridge system are divided into two regimes with a discontinuity at a position roughly 1,000 km northwest of Kilauea; the estimated age of this discontinuity is about 10 m.y. Other episodes relate to the durations of eruptive sequences along individual or contiguous lines of volcanoes within the en échelon set of locus lines defined by Jackson and others. The latest of these episodes, beginning about 6 m.y. ago, is marked by accelerating volume rates of eruption and accelerating rates of ridge propagation; this episode appears to be approaching a culminating stage represented by the present activity of Kilauea Volcano. The calculated rate of eruption of Kilauea (0.11 km 3 per yr) is virtually identical with a rate independently estimated by Swanson in 1972 using different data. Calculated durations for older locus lines are generally greater than 6 m.y., but major time overlaps occur that are not adequately understood. Episodic behavior of shorter durations also exists relative to growth of individual shields or to synchronous activity on neighboring shields (for example, Mauna Loa and Kilauea). Some of these shorter term effects are partly explained in terms of isostatic factors acting on the lithosphere and asthenosphere. The longer episodes are explained in terms of variations of melting rates in the asthenosphere, governed by viscous heating produced by the interaction of lithosphere translation and both vertical and horizontal shear flows in the subjacent mantle. Accelerations of eruption and propagation rates are explained by melting instabilities in the upper zones of the asthenosphere as a result of thermal feedback. During the latest melting episode, shear stresses in the asthenosphere derived from the rate data as interpreted by the thermal feedback model are in the range 100 to 200 bars; apparent viscosities range from 2 × 10 21 to 4 × 10 20 poise, decreasing with increasing melting rate. In general, a thermomechanical model is shown to be consistent with the idea that oceanic melting spots can be fixed relative to the deep mantle, although this invariance is not completely established. The thermal plume model of Morgan is not definitely ruled out but does not seem to be required for internally consistent interpretations of oceanic chains of volcanism. It is concluded that motion vectors of the Pacific plate cannot be inferred directly from rates of propagation of volcanic chains, because these rates reflect local, not average, relative velocities of lithosphere versus mantle flow. During growth of the Hawaiian Ridge, propagation speeds calculated on the basis of rate data for the southeastern Hawaiian Islands ranged from less than 1 cm per yr near the Hawaiian-Emperor Bend to nearly 30 cm per yr at the present ridge front.

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USGS1973

Flow of lava into the sea, 1969–1971, Kilauea Volcano, Hawaii

Lava from the Mauna Ulu eruption on Kilauea Volcano entered the sea on the south coast of the Island of Hawaii three times from 1969 to 1971. Two of these flows were investigated underwater by divers, one while lava was actively flowing. The June 1969 flow entered the sea as a narrow flow of aa. Below sea level, the flow maintained continuity and flowed at least several hundred meters to a depth beyond 70 m. Several cylindrical flow lobes about 1 m in diameter and about 10 to 15 m long emerged from the side of the aa flow at a depth of about 25m. Underwater investigations, combined with subaerial observations, revealed that the March–May 1971 flow produced a distinct lava delta composed of subaerial pahoehoe lava resting on a submarine sequence of steeply dipping foreset-bedded volcanic sand and rubble that includes conformably dipping cylindrical lava tongues. Most of the pahoehoe streams pouring over the sea cliff are quenched and shattered to glassy sand and rubble that in turn is further fragmented by vigorous wave action and avalanching. In some places, however, larger pahoehoe flows maintain coherence across the cliff and through the surf zone to feed submarine lava tongues. Underwater, these active lava tongues emitted a roaring noise as lava flowed inside their outer black glassy walls. Periodically, cracks exposed the brightly incandescent lava within, and pillow-like buds and toes grew from the top and sides of the lava tongue. Only a small amount of steam was generated underwater. Water temperature close to the active tongues was elevated only 2.5°C.

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USGS1973

Magma Mixing as Illustrated by the 1959 Eruption, Kilauea Volcano, Hawaii

The 1959 eruption of Kilauea volcano is unique among recent Kilauea summit eruptions (1952 to 1968) in at least two respects: (1) a large collapse of Kilauea summit accompanied the eruption, and (2) the erupted lavas show a complex variation in their bulk chemical composition. Both features suggest that the 1959 eruption was fed from a source different from that which fed other summit eruptions in this period. The variations in chemical composition can be interpreted in terms of mixing chromite-bearing olivine with variable proportions of two “end-member” magmas represented by the composition of samples of pumice erupted during the first phase of the eruption. Mixing calculations show that the MgO content of olivine varies with the MgO content of the lava and thus with olivine percentage in the same manner as previously determined by Richter and Murata (1966) from petrographic study of hand samples. The calculations also show that the proportion of the two end-member magma types varies throughout the eruption. These results suggest that the eruption was fed from two separate magma batches, each of which was held in a reservoir with an olivine-poor top and olivine accumulation toward the bottom. There is also evidence that the two end-member magmas may be related by redistribution of clinopyroxene in a third hypothetical magma. The complex pre-eruption history implied by the chemical data is at present not satisfactorily explained by any physical model of fractionation, storage, and mixing that can be inferred from data on other well-studied Kilauea eruptions. The average MgO content (15.5 percent) of the 1959 eruption is estimated to be in minimum MgO content of magma produced by partial melting in the mantle beneath Kilauea.

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USGS1973

Hydrology and sediment transport, Moanalua Valley, Oahu, Hawaii

The first 2 years of intensive data collection in Moanalua Valley have resulted in some observations concerning the rainfall- runoff and rainfall-sedimentation characteristics of the basin. This initial study period has been concerned primarily with establishing a reliable hydrologic data-collection network. However, enough data have been collected to determine that rainfall within the valley shows extreme areal variations from one storm to another. An initial run on the U.S. Geological Survey small watershed model indicates some differences in basin characteristics in the two upper subregions. Results of model studies to date are encouraging. Flood routing with the Corps of Engineers' HEC-1 flood hydrograph package seems to be feasible. By preliminary estimates, the 50-year flood at gage 2282 would probably be between 5,500 and 6,000 cubic feet per second. The narrow, steep nature of Moanalua Valley results in very rapid concentration of runoff, with extremely sharp hydrograph peaks. Stream channel width ranges from about 20 feet in the headwaters to 35 feet near the downstream limit of the study area. Mean slope of the main stem is about 0.027 foot/foot.1/ Where not identified, units for slope are ft/ft. Observations indicate that the stream transports very large particles (in excess of 2 feet in diameter) quite frequently. Detached fragments from old stone-arch bridges have been marked in the channel fill for use as tracers. Only one storm has been analyzed for suspended-sediment discharge, but rough calculations indicate a possible suspended-sediment load of 12,000 tons for a storm similar to the design flow at gage 2282. This compares with a computed bedload discharge of 2,600 tons for the same flow. Accumulation in the debris basin between October 2, 1969 and July 26, 1971, as measured by level survey, was 48,000 cubic feet or about 2,900 tons.

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USGS1973

Petrology, mineralogy and geochemistry of the lava of East Molokai Volcano, Hawaii

The island of Molokai, a volcanic doublet, is the fifth in size of the islands of the Hawaiian Archipelago, which extends about 2500 km (1554 mi) southeastward across the central Pacific Ocean from Kure on the northwest to Hawaii on the southeast (Fig. 1). The broadly linear chain of islands which make up the archipelago caps the Hawaiian Ridge, a pronounced topographic high on the Hawaiian Swell. The ridge is bordered by the Hawaiian Moat (or Deep) which is in turn bordered by the Hawaiian Arch (or Rise). These three topographic features, the ridge, moat and arch, are superposed on a broad elongate ridge, the Hawaiian Swell (Betz and Hess, 1942; Dietz and Menard, 1953). Dana (1849, 1890) recognized from geomorphic evidence that extinction of the chain progressed from northwest to southeast, and McDougall (1964) confirmed the general progression with K-Ar ages of lavas from Kauai, Oahu, Molokai, Maui and Hawaii. The general progression of ages of the Hawaiian-Emperor chain and its relation to Cenozoic Circumpacific tectonics has been described by Jackson et al. (1972) and Dalrymple et al. (1973). Fiske and Jackson (1972) have investigated the influence of regional structure and local gravitational stresses on the orientation and growth of Hawaiian volcanic rifts. Macdonald and Abbott (1970) give an excellent summary of the geomorphology of the Hawaiian Islands and of the processes that formed, and are continuing to form them. This summary contains a geologic sketch of each of the major windward islands (extending from Kauai to Hawaii) individually, and the leeward islands (extending from Kure to Nihoa) as a group.

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USGS1973

Loss of volatiles during fountaining and flowage of basaltic lava at Kilauea Volcano, Hawaii

The amount of water and sulfur in pumice erupted during periods of vigorous activity during the 1969-71 Mauna Ulu eruption varied inversely with fountain height because of degassing during the fountaining. The pumice lost about 0.05 wt percent water and 0.003 wt percent sulfur during fountaining to heights of 400-540 m. Analyses suggest that the initial volatile content of Mauna Ulu lava was greater immediately preceding periods of high fountaining than during weak activity between those periods or after the last high fountains on December 30, 1969. Water and sulfur were systematically depleted during nearly isothermal flowage in lava tubes. Rapidly quenched samples of dipped melt show losses of about 0.03-0.04 wt percent water and 0.007-0.008 wt percent sulfur during flowage for several hours through a distance of 12 km. Glassy skins on cooled pahoehoe flows contain about 0.002-0.003 wt percent less sulfur than quenched melt at comparable distances from the vent, because of continued degassing under natural cooling conditions. Chlorine shows similar but less well defined trends. Pumice erupted in high fountains becomes more strongly oxidized than the parent magma, because of mixing with air while still at high temperatures.

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USGS1973

Chemical quality of ground water in Hawaii

As the quantity of water needed in certain localities of Hawaii is rapidly approaching the quantity of usable water available, identification and protection of the quality of existing and potential water supplies are becoming ever more critical. Certain factors are already identifiable as problems affecting the quality of ground water in Hawaii: (1) over-development leads to salt-water encroachment by local upconing; (2) agricultural and industrial uses and discharges deteriorate both present and potential water supplies; and (3) the increasing practice of underground disposal of domestic wastes, with insufficient information to protect the water resource creates a potential hazard to developed and future supplies.

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USGS1972

The complex filling of alae crater, Kilauea Volcano, Hawaii

Since February 1969 Alae Crater, a 165-m-deep pit crater on the east rift of Kilauea Volcano, has been completely filled with about 18 million m 3 of lava. The filling was episodic and complex. It involved 13 major periods of addition of lava to the crater, including spectacular lava falls as high as 100 m, and three major periods of draining of lava from the crater. Alae was nearly filled by August 3, 1969, largely drained during a violent ground-cracking event on August 4, 1969, and then filled to the low point on its rim on October 10, 1969. From August 1970 to May 1971, the crater acted as a reservoir for lava that entered through subsurface tubes leading from the vent fissure 150 m away. Another tube system drained the crater and carried lava as far as the sea, 11 km to the south. Much of the lava entered Alae by invading the lava lake beneath its crust and buoying the crust upward. This process, together with the overall complexity of the filling, results in a highly complicated lava lake that would doubtless be misinterpreted if found in the fossil record.

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USGS1972

Magma supply rate at Kilauea volcano, 1952-1971

The three longest Kilauea eruptions since 1952 produced lava at an overall constant rate of about 9 x 10 6 cubic meters per month (vesicle-free). This is considered to represent the rate of magma supply from a deep source, probably the mantle, because little or no summit deformation indicating high-level storage accompanied any of the three eruptions.

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USGS1972

Hawaiian-emperor chain and its relation to cenozoic circumpacific tectonics

The Hawaiian Ridge and Emperor Seamounts appear to form a single chain of tholeiitic shield volcanoes that erupted sequentially on the sea floor of the central Pacific Ocean during Tertiary and Quaternary time. The chain cuts obliquely across the older Cretaceous structural patterns of that sea floor. While the pattern of the chain as a whole is linear, the individual volcanoes lie on short, sigmoidal, en echelon loci that are subparallel with respect to each other and that may represent extensional features in the crust and upper mantle. In general, the order of eurption progressed from northwest to southeaśt along the chain, but the rate of progression of volcanism along individual loci is nonlinear where best studied in the southeastern part of the chain. Furthermore, simultaneous eruptions appear to have occurred within a distance along the chain of about 200 to 400 km. The available data are consistent with a genesis related to the motion of the Pacific crust over a melting spot in the mantle. This melting spot, which may be due to either excess heat or pressure release, appears to have a diameter of about 300 km and is presently centered slightly north of the island of Hawaii. We concur with the idea that the bend in the Hawaiian-Emperor chain probably reflects a significant change in the motion of the Pacific plate. Our best estimate of the age of the Hawaiian-Emperor bend, based on the existing radiometric data, is 24.6 ± 2.5 m.y., which correlates with a time of increased tectonic activity in the western Pacific island arcs and along the northern and eastern boundaries of the Pacific plate. The vector change in the motion of the Pacific plate (with respect to the melting spot) that is required to produce the bend is about 12 cm/yr in a west-southwest-ward direction. © 1972, The Geological Society of America, Inc.

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USGS1972

Evaluation of the streamflow-data program in Hawaii

Streamflow data for Hawaii are evaluated and guidelines for planning future data programs are provided. Evaluation involved (1) definition of long-term goals of the data-collection program in quantitative form, (2) examination and analysis of all available data to determine which goals have been achieved, and (3) consideration of alternative programs and techniques to overcome shortcomings in the present network and to increase benefits from future programs.

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