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Research about Hawaii

Source-linked reports with geographic coverage including Hawaii.

At least 757 records · Page 42Linked to original sources
USGS2006

North Kona slump: Submarine flank failure during the early(?) tholeiitic shield stage of Hualalai Volcano

The North Kona slump is an elliptical region, about 20 by 60 km (1000-km 2 area), of multiple, geometrically intricate benches and scarps, mostly at water depths of 2000–4500 m, on the west flank of Hualalai Volcano. Two dives up steep scarps in the slump area were made in September 2001, using the ROV Kaiko of the Japan Marine Science and Technology Center (JAMSTEC), as part of a collaborative Japan–USA project to improve understanding of the submarine flanks of Hawaiian volcanoes. Both dives, at water depths of 2700–4000 m, encountered pillow lavas draping the scarp-and-bench slopes. Intact to only slightly broken pillow lobes and cylinders that are downward elongate dominate on the steepest mid-sections of scarps, while more equant and spherical pillow shapes are common near the tops and bases of scarps and locally protrude through cover of muddy sediment on bench flats. Notably absent are subaerially erupted Hualalai lava flows, interbedded hyaloclastite pillow breccia, and/or coastal sandy sediment that might have accumulated downslope from an active coastline. The general structure of the North Kona flank is interpreted as an intricate assemblage of downdropped lenticular blocks, bounded by steeply dipping normal faults. The undisturbed pillow-lava drape indicates that slumping occurred during shield-stage tholeiitic volcanism. All analyzed samples of the pillow-lava drape are tholeiite, similar to published analyses from the submarine northwest rift zone of Hualālai. Relatively low sulfur (330–600 ppm) and water (0.18–0.47 wt.%) contents of glass rinds suggest that the eruptive sources were in shallow water, perhaps 500–1000-m depth. In contrast, saturation pressures calculated from carbon dioxide concentrations (100–190 ppm) indicate deeper equilibration, at or near sample sites at water depths of − 3900 to − 2800 m. Either vents close to the sample sites erupted mixtures of undegassed and degassed magmas, or volatiles were resorbed from vesicles during flowage downslope after eruption in shallow water. The glass volatile compositions suggest that the tholeiitic lavas that drape the slump blocks were erupted either (1) early during shield-stage tholeiitic volcanism prior to emergence of a large subaerial edifice, or alternatively (2) from submarine radial vents during subaerial shield-building. Because no radial vents have been documented on land or underwater for the unbuttressed flanks of any Hawaii volcano, alternative (1) is favored. In comparison to other well-documented Hawaiian slumps and landslides, North Kona structures suggest a more incipient slump event, with smaller down-slope motions and lateral displacements.

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USGS2006

Youngest volcanism about 1 million years ago at Kahoolawe Island, Hawaii

Young volcanic deposits in Kahoolawe Island, cutting up through the caldera-filling lava, colluvium and talus in the west wall of Kanapou Bay, had long been stratigraphically considered the rejuvenated-stage products. New K-Ar ages, combined with magnetic polarity data, show that young volcanism was at about 0.98-1.04 Ma and indicate no substantial quiescence between the filling of the caldera and the young volcanism. This result, and the tholeiitic characteristics of the young deposits, suggest they are a component of late shield-stage volcanism. ?? 2005 Elsevier B.V. All rights reserved.

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USGS2006

Perspectives on basaltic magma crystallization and differentiation: Lava-lake blocks erupted at Mauna Loa volcano summit, Hawaii

Explosive eruptions at Mauna Loa summit ejected coarse-grained blocks (free of lava coatings) from Moku'aweoweo caldera. Most are gabbronorites and gabbros that have 0–26 vol.% olivine and 1–29 vol.% oikocrystic orthopyroxene. Some blocks are ferrogabbros and diorites with micrographic matrices, and diorite veins (≤2 cm) cross-cut some gabbronorites and gabbros. One block is an open-textured dunite. The MgO of the gabbronorites and gabbros ranges ∼ 7–21 wt.%. Those with MgO >10 wt.% have some incompatible-element abundances (Zr, Y, REE; positive Eu anomalies) lower than those in Mauna Loa lavas of comparable MgO; gabbros (MgO <10 wt.%) generally overlap lava compositions. Olivines range Fo 83–58 , clinopyroxenes have Mg#s ∼83–62, and orthopyroxene Mg#s are 84–63 — all evolved beyond the mineral-Mg#s of Mauna Loa lavas. Plagioclase is An 75–50 . Ferrogabbro and diorite blocks have ∼ 3–5 wt.% MgO (TiO 2 3.2–5.4%; K 2 O 0.8–1.3%; La 16–27 ppm), and a diorite vein is the most evolved (SiO 2 59%, K 2 O 1.5%, La 38 ppm). They have clinopyroxene Mg#s 67–46, and plagioclase An 57–40 . The open-textured dunite has olivine ∼ Fo 83.5 . Seven isotope ratios are 87 Sr/ 86 Sr 0.70394–0.70374 and 143 Nd/ 144 Nd 0.51293–0.51286, and identify the suite as belonging to the Mauna Loa system. Gabbronorites and gabbros originated in solidification zones of Moku'aweoweo lava lakes where they acquired orthocumulate textures and incompatible-element depletions. These features suggest deeper and slower cooling lakes than the lava lake paradigm, Kilauea Iki, which is basalt and picrite. Clinopyroxene geobarometry suggests crystallization at <1 kbar P. Highly evolved mineral Mg#s, <75, are largely explained by cumulus phases exposed to evolving intercumulus liquids causing compositional ‘shifts.’ Ferrogabbro and diorite represent segregation veins from differentiated intercumulus liquids filter pressed into rigid zones of cooling lakes. Clinopyroxene geobarometry suggests <300 bar P. Open-textured dunite represents olivine-melt mush, precursor to vertical olivine-rich bodies (as in Kilauea Iki). Its Fo 83.5 identifies the most primitive lake magma as ∼8.3 wt.% MgO. Mass balancing and MELTS show that such a magma could have yielded both ferrogabbro and diorite by ≥50% fractional crystallization, but under different fO 2 : < FMQ (250 bar) led to diorite, and FMQ (250 bar) yielded ferrogabbro. These segregation veins, documented as similar to those of Kilauea, testify to appreciable volumes of ‘rhyolitic’ liquid forming in oceanic environments. Namely, SiO 2 -rich veins are intrinsic to all shields that reached caldera stage to accommodate various-sized cooling, differentiating lava lakes.

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USGS2006

Shelf stratigraphy and the influence of antecedent substrate on Holocene reef development, south Oahu, Hawaii

Paired analyses of drill cores and high-resolution seismic reflection data show that development of Holocene framework reefs on the Oahu (Hawaii) shelf is limited to settings of low wave energy and to the period 8000 to 3000 yr BP. A prominent bounding surface that is mapped across much of the Oahu shelf is an erosion surface cut into Marine Isotope Stages 5 and 7 limestones that show extensive loss of primary porosity, aragonite, and MgCO3 owing to meteoric and vadose-zone diagenesis. This acoustic reflector is found exposed at the surface where wave energy is high or in the shallow subsurface below Holocene reef and sand sheet deposits where energy is low. Ship-towed video along 30 km of the shelf reveals a steady decrease in limestone accumulation from offshore of Honolulu southeast to Koko Head where the seafloor is characterized by volcanic pavement and/or thin sand deposits. This may reflect the build-up of late Pleistocene volcanics associated with the Hanauma Bay eruption (30,000-7000 yr BP) that now comprise the substrate in depths shallow enough to limit reef accretion. The absence of significant Holocene reef build-up on the south Oahu shelf is consistent with observations from north-facing coasts that lack Holocene reefs, indicating that Holocene reef formation in Hawaii is complex and patchy.

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USGS2006

Quantity, composition, and source of sediment collected in sediment traps along the fringing coral reef off Molokai, Hawaii

Sediment traps were used to evaluate the frequency, cause, and relative intensity of sediment mobility/resuspension along the fringing coral reef off southern Molokai (February 2000–May 2002). Two storms with high rainfall, floods, and exceptionally high waves resulted in sediment collection rates > 1000 times higher than during non-storm periods, primarily because of sediment resuspension by waves. Based on quantity and composition of trapped sediment, floods recharged the reef flat with land-derived sediment, but had a low potential for burying coral on the fore reef when accompanied by high waves. The trapped sediments have low concentrations of anthropogenic metals. The magnetic properties of trapped sediment may provide information about the sources of land-derived sediment reaching the fore reef. The high trapping rate and low sediment cover indicate that coral surfaces on the fore reef are exposed to transient resuspended sediment, and that the traps do not measure net sediment accumulation on the reef surface.

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USGS2006

Influence of propagule flotation longevity and light availability on establishment of introduced mangrove species in Hawai'i

Although no mangrove species are native to the Hawaiian Archipelago, both Rbizopbora mangle and Bruguiera sexangula were introduced and have become naturalized. Rbizopbora mangle has spread to almost every major Hawaiian island, but B. sexangula has established only on O'ahu, where it was intentionally introduced. To examine the possibility that differences in propagule characteristics maintain these patterns of distribution, we first reviewed the literature on surface currents around the Hawaiian Islands, which suggest that propagules ought to disperse frequently from one island to another within 60. days. We then tested the ability of propagules of the two species to float for periods of up to 63 days and to establish under two light intensities. On average, R. mangle propagules floated for longer periods than those of B. sexangula , but at least some propagules of both species floated for a full 60 days and then rooted and grew for 4 months under relatively dense shade. A large percentage (???83%) of R. mangle propagules would be expected to float beyond 60 days, and approximately 10% of B. sexangula propagules also would have remained afloat. Therefore, it seems likely that factors other than flotation ability are responsible for the failure of B. sexangula to become established on other Hawaiian islands.

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USGS2006

Identifying the effects of petrologic processes in a closed basaltic system using trace element concentrations in olivines and glasses: Implications for comparative planetology

We use trace-element concentrations in olivines and glasses from a closed basaltic system to identify the effects of petrologic processes on the trace-element record of that system. The closed basaltic system in question is the Makaopuhi Lava Lake (MLL), which is closed with respect to magma mixing. Detailed studies of this lava lake have provided important information about system variables and petrologic processes that have been measured and observed at the lake. These previous studies show that olivine crystallized from the lava lake at all stages of the lake’s evolution, which means that olivine and residual glasses contain a record of the lake’s petrologic history. We use this information, in conjunction with variations in trace-element concentrations in olivines and glasses, to show that mineral crystallization, gravitational settling, convective flow, filter pressing, and mineral-melt interface kinetics have characteristic effects on the trace element record of a closed basaltic system. These results are pertinent to the field of comparative planetology because they can be used to evaluate petrologic information in small samples from other planetary bodies, where information about system variables and/or petrologic processes is limited.

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USGS2006

JAMSTEC multibeam surveys and submersible dives around the Hawaiian Islands: A collaborative Japan-USA exploration of Hawaii's deep seafloor

This database release, USGS Data Series 171, contains data collected during four Japan-USA collaborative cruises that characterize the seafloor around the Hawaiian Islands. The Japan Agency for Marine-Earth Science and Technology (JAMSTEC) sponsored cruises in 1998, 1999, 2001, and 2002, to build a greater understanding of the deep marine geology around the Hawaiian Islands. During these cruises, scientists surveyed over 600,000 square kilometers of the seafloor with a hull-mounted multibeam seafloor-mapping sonar system (SEA BEAM® 2112), observed the seafloor and collected samples using robotic and manned submersible dives, collected dredge and piston-core samples, and performed single-channel seismic surveys.

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USGS2006

Geologic map of the middle east rift geothermal subzone, Kīlauea Volcano, Hawaiʻi

Kīlauea is an active shield volcano in the southeastern part of the Island of Hawai'i. The middle east rift zone (MERZ) map includes about 27 square kilometers of the MERZ and shows the distribution of the products of 37 separate eruptions during late Holocene time. Lava flows erupted during 1983-96 have reached the mapped area. The subaerial part of the MERZ is 3-4 km wide and about 18 km long. It is a constructional ridge, 50-150 m above the adjoining terrain, marked by low spatter ramparts and cones as high as 60 m. Lava typically flowed either northeast or southeast, depending on vent location relative to the topographic crest of the rift zone. The MERZ receives more than 100 in. of rainfall annually and is covered by tropical rain forest. Vegetation begins to grow on lava a few months after its eruption. Relative heights of trees can be a guide to relative ages of underlying lava flows, but proximity to faults, presence of easily weathered cinders, and human activity also affect the rate of growth. The rocks have been grouped into five basic age groups. The framework for the ages assigned is provided by eight radiocarbon ages from previous mapping by the authors and a single date from the current mapping effort. The numerical ages are supplemented by observations of stratigraphic relations, degree of weathering, soil development, and vegetative cover.

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USGS2006

Coastal vulnerability assessment of Kaloko-Honokohau National Historical Park to sea-level rise

A coastal vulnerability index (CVI) was used to map the relative vulnerability of the coast to future sea-level rise within Kaloko-Honokohau National Historical Park in Hawaii. The CVI ranks the following in terms of their physical contribution to sea-level rise-related coastal change: geomorphology, regional coastal slope, rate of relative sea-level rise, historical shoreline change rates, mean tidal range and mean significant wave height. The rankings for each input variable were combined, and an index value calculated for 500-meter grid cells covering the park. The CVI highlights those regions where the physical effects of sea-level rise might be the greatest. This approach combines the coastal system's susceptibility to change with its natural ability to adapt to changing environmental conditions, yielding a quantitative, although relative, measure of the park's natural vulnerability to the effects of sea-level rise. The CVI provides an objective technique for evaluation and long-term planning by scientists and park managers. Kaloko-Honokohau National Historical Park consists of carbonate sand beaches, coral rubble, rocky shoreline, and mangrove wetland areas. The areas within Kaloko-Honokohau National Historical Park that are likely to be most vulnerable to sea-level rise based on this analysis are areas of unconsolidated sediment and highest wave energy.

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USGS2006

Coastal circulation and sediment dynamics in Hanalei Bay, Kauai, Part I, Measurements of waves, currents, temperature, salinity and turbidity; June–August, 2005

High-resolution measurements of waves, currents, water levels, temperature, salinity and turbidity were made in Hanalei Bay, northern Kauai, Hawaii, during the summer of 2005 to better understand coastal circulation and sediment dynamics in coral reef habitats. A series of bottom-mounted instrument packages were deployed in water depths of 10 m or less to collect long-term, high-resolution measurements of waves, currents, water levels, temperature, salinity and turbidity. These data were supplemented with a series of vertical instrument casts to characterize the vertical and spatial variability in water column properties within the bay. The purpose of these measurements was to collect hydrographic data to learn how waves, currents and water column properties vary spatially and temporally in an embayment that hosts a nearshore coral reef ecosystem adjacent to a major river drainage. These measurements support the ongoing process studies being conducted as part of the U.S. Geological Survey (USGS) Coastal and Marine Geology Program's Coral Reef Project; the ultimate goal is to better understand the transport mechanisms of sediment, larvae, pollutants and other particles in coral reef settings. This report, the first part in a series, describes data acquisition, processing and analysis.

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USGS2006

Borehole dilatometer installation, operation, and maintenance at sites in Hawaii

In response to concerns about the potential hazard of Mauna Loa volcano in Hawaii, the USGS began efforts in 1998 to add four high-resolution borehole sites. Located at these sites are; strainmeters, tiltmeters, seismometers, accelerometers and other instrumentation. These instruments are capable of providing continuous monitoring of the magma movement under Mauna Loa. Each site was planned to provide multi-parameter monitoring of volcanic activity. In June of 2000, a contract was let for the core drilling of three of these four sites. They are located at Hokukano (west side of Mauna Loa) above Captain Cook, Hawaii; at Mauna Loa Observatory (11,737 feet near the summit), and at Mauna Loa Strip Road (east side of Mauna Loa). Another site was chosen near Halema'uma u' and Kilauea's summit, in the Keller deep well. (See maps). The locations of these instruments are shown in Figure 1 with their latitude and longitude in Table 1. The purpose of this network is to monitor crustal deformation associated with volcanic intrusions and earthquakes on Mauna Loa and Kilauea volcanoes. This report describes the methods used to locate sites, install dilatometers, other instrumentation, and telemetry. We also provide a detailed description of the electronics used for signal amplification and telemetry, plus techniques used for instrument maintenance. Instrument sites were selected in regions of hard volcanic rock where the expected signals from magmatic activity were calculated to be a maximum and the probability of earthquakes with magnitude 4 or greater is large. At each location, an attempt was made to separate tectonic and volcanic signals from known noise sources for each instrument type.

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USGS2006

Coastal circulation and sediment dynamics in Hanalei Bay, Kaua'i, Hawaii: Part II: Tracking recent fluvial sedimentation: Isotope stratigraphy obtained in Summer 2005

Delivery and dispersal of fluvial sediment in Hanalei Bay, Kaua’i, Hawaii, have important implications for the health of local coral reefs. The reef community in Hanalei Bay represents a relatively healthy ecosystem. However, the reefs are periodically stressed by storm waves, and increases in sediment and dissolved substances from the Hanalei River have the potential to cause additional stress. Increased turbidity and sedimentation on corals during Hanalei River floods that occur in seasons of low wave energy, when sediment would not be readily remobilized and advected out of the bay, could affect the health and sustainability of coral reefs and the many associated species. Measurements of short-lived isotopes 7 Be and 137 Cs in sediment cores have been used to trace the thickness and distribution of terrestrial sediment in Hanalei Bay, in order to assess spatial and temporal patterns of sediment deposition and remobilization relative to coral-reef locations. A third isotope, 210 Pb, derived primarily from seawater, provides additional information about recent sedimentary history. Isotope profiles and observations of sedimentary facies from cores collected at multiple locations in June 2005, and again in August 2005, indicate the presence of recent fluvial sediment and organic debris in the east part of the bay near the mouth of the Hanalei River. Away from the immediate vicinity of the river mouth, sediment in the uppermost 1 m below the sea floor had not retained a significant quantity of fluvial sediment within the eight months prior to either sampling effort. During the study interval in summer 2005 the Hanalei River had no major floods and there was relatively little sediment input to the bay. Sediment away from the river mouth was dominated by carbonate sand, although some terrestrial sediment was present in sub-sea-floor horizons. Sedimentary facies and isotope inventories throughout the bay showed substantial spatial heterogeneity. Sediment cores will be collected again at the same sites discussed here during early and late summer 2006. If possible, additional sites will be sampled in the Black Hole depocenter near the river mouth. Major floods in winter and spring 2006 are expected to leave a significant new sediment signal in the bay that should be detected in summer 2006.

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USGS2006

Coastal circulation and sediment dynamics in Hanalei Bay, Kaua'i, Hawaii. Part III: Studies of sediment toxicity

Toxicity tests are commonly conducted as a measure of the bioavailability of toxic chemicals to biota in an environment. Chemical analyses alone are insufficient to determine whether contaminants pose a threat to biota. Porewater toxicity tests are extremely sensitive to a broad range of contaminants in marine environments and provide ecologically relevant data on sensitive life stages. The inclusion of porewater toxicity testing as an additional indicator of sediment quality provides a more comprehensive picture of contaminant effects in these sensitive habitats. In this study purple-spined sea urchin (Arbacia punctulata) fertilization and embryological development porewater toxicity tests were used to evaluate the sediments collected from the coastal environment around Hanalei Bay, Kaua’i, Hawaii. These tests have been used previously to assess the bioavailability of contaminants associated with sediments in the vicinity of coral reefs.

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USGS2005

An efficient algorithm for double-difference tomography and location in heterogeneous media, with an application to the Kilauea volcano

Improving our understanding of crustal processes requires a better knowledge of the geometry and the position of geological bodies. In this study we have designed a method based upon double-difference relocation and tomography to image, as accurately as possible, a heterogeneous medium containing seismogenic objects. Our approach consisted not only of incorporating double difference in tomography but also partly in revisiting tomographic schemes for choosing accurate and stable numerical strategies, adapted to the use of cross-spectral time delays. We used a finite difference solution to the eikonal equation for travel time computation and a Tarantola-Valette approach for both the classical and double-difference three-dimensional tomographic inversion to find accurate earthquake locations and seismic velocity estimates. We estimated efficiently the square root of the inverse model's covariance matrix in the case of a Gaussian correlation function. It allows the use of correlation length and a priori model variance criteria to determine the optimal solution. Double-difference relocation of similar earthquakes is performed in the optimal velocity model, making absolute and relative locations less biased by the velocity model. Double-difference tomography is achieved by using high-accuracy time delay measurements. These algorithms have been applied to earthquake data recorded in the vicinity of Kilauea and Mauna Loa volcanoes for imaging the volcanic structures. Stable and detailed velocity models are obtained: the regional tomography unambiguously highlights the structure of the island of Hawaii and the double-difference tomography shows a detailed image of the southern Kilauea caldera-upper east rift zone magmatic complex. Copyright 2005 by the American Geophysical Union.

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USGS2005

Thermal observations of gas pistoning at Kilauea Volcano

Data acquired by three continuously recording thermal infrared thermometers situated on the north rim of Pu'u'O' o Crater at Kilauea Volcano during 2002 revealed episodes of periodic thermal pulses originating from a degassing vent on the crater floor. These thermal pulses are interpreted as gas release (jetting events) associated with gas pistoning, a mechanism observed previously at both Mauna Ulu and Pu'u'O' o. During a 35-day-long period spanning June and July 2002, gas pistoning was frequently the dominant mode of gas release, with as many as several hundred pulses occurring in uninterrupted series. On other days, degassing alternated between periods of quasi-continuous gas jetting and intervals of gas pistoning that contained a few to a few dozen pulses. Characteristic time intervals between pistoning events ranged from 2 up to 7 min. We identify three types of pistoning. Type 1 involves emission of lava, followed by gas jetting and drain back; type 2 is the same but the elevated position of the vent does not allow postjet drain back; and type 3 involves gas jetting only with no precursory lava flow. To explain gas pistoning, we apply a model whereby a stagnant cap of degassed magma develops in the conduit below the vent. Gas bubbles rise through the magma column and collect under the cap. The collective buoyancy of these bubbles pushes the cap upward. When the cap reaches the surface, it erupts from the vent as a lava flow. Unloading of the conduit magma in this way results in an abrupt pressure drop (i.e., the overburden felt by the bubbles is reduced), causing explosive gas expansion in the form of gas jetting from the vent. This terminates the event and lava drains back into the conduit to start the cycle anew. In the case where there is no surface lava emission or drain back, the cap instead pushes into and spreads out within a subsurface cavity. Again, this unloads the conduit magma and terminates in explosive gas release. Once gas is expelled, lava in the cavity is free to drain back. We hypothesize that pistoning is a stable mode of degassing for low-viscosity basaltic magmas with appropriate conduit geometries and volatile supply rates. Copyright 2005 by the American Geophysical Union.

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USGS2005

The role of abiotic conditions in shaping the long-term patterns of a high-elevation Argentine ant invasion

Analysis of long-term patterns of invasion can reveal the importance of abiotic factors in influencing invasion dynamics, and can help predict future patterns of spread. In the case of the invasive Argentine ant (Linepithema humile), most prior studies have investigated this species' limitations in hot and dry climates. However, spatial and temporal patterns of spread involving two ant populations over the course of 30 years at a high elevation site in Hawaii suggest that cold and wet conditions have influenced both the ant's distribution and its rate of invasion. In Haleakala National Park on Maui, we found that a population invading at lower elevation is limited by increasing rainfall and presumably by associated decreasing temperatures. A second, higher elevation population has spread outward in all directions, but rates of spread in different directions appear to have been strongly influenced by differences in elevation and temperature. Patterns of foraging activity were strongly tied to soil temperatures, supporting the hypothesis that variation in temperature can influence rates of spread. Based on past patterns of spread, we predicted a total potential range that covers nearly 50% of the park and 75% of the park's subalpine habitats. We compared this rough estimate with point predictions derived from a degree-day model for Argentine ant colony reproduction, and found that the two independent predictions match closely when soil temperatures are used in the model. The cold, wet conditions that have influenced Argentine ant invasion at this site are likely to be influential at other locations in this species' current and future worldwide distribution.

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