Geology topics

Research about Hawaii

Source-linked reports with geographic coverage including Hawaii.

At least 415 records · Page 23Linked to original sources

USGS2019

3D electrical conductivity imaging of Halema‘uma‘u lava lake (Kīlauea volcano)

Before the 2018 collapse of the summit of Kīlauea volcano, a ca. 200 m in diameter lava lake inside of Halema‘uma‘u crater was embedded in a very active hydrothermal system. In 2015, we carried out an electrical conductivity survey and the data were inverted in 3D. The lack of conductivity contrast precludes distinguishing the lava column from the surrounding hydrothermal zones. Laboratory measurements on samples from the lava lake show that the conductivity of magma is significantly lower than that of hydrothermal zones but the high vesicularity of the upper part of the lava lake may decrease its macroscopic conductivity. Based on the 3D conductivity model, we distinguish at least two types of hydrothermal circulations: 1) one guided by the collapse faults of Halema‘uma‘u crater and by the magmatic column of the lava lake, and 2) another guided by previous caldera faults and fractures related to intrusions. We observe that the location of the faults formed during the 2018 collapse of the summit was greatly influenced by the hydrothermally altered zones.

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USGS2019

Geochemical sourcing of runoff from a young volcanic watershed to an impacted coral reef in Pelekane Bay, Hawaii

Runoff of sediment and other contaminants from developed watersheds threatens coastal ecosystems and services. A sediment geochemical sourcing study was undertaken on a sediment-impacted coral reef flat to identify terrestrial sediment sources and how these changed over time. Geochemical signatures were identified for watershed soils that formed on Hawaiian basaltic and alkalic lavas using relatively immobile compatible (Ni, Sc) and incompatible (Nb, REE , Th) elements quantified by ICP-MS in total decompositions of the fine fraction of surface soils. Some soils also contained ash from late-erupting cinder cones that added alkalic geochemical signatures, resulting in distinctive mixed signatures near these geologic features. Sediment was collected in Pelekane Bay using sediment traps during winter 2010–2011 and a sediment core in order to geochemically source runoff entering the bay. Geochemical signatures in trapped sediment showed that runoff predominantly originated from the lower watershed along a highway corridor rather than from the upper watershed or areas with alkalic lavas. Soil in the highway corridor also contained Zn above levels of concern for aquatic organisms and anthropogenic Pb, indications that runoff control measures could reduce the exposure of the reef community to potentially toxic metals and other road-associated contaminants. The upper portion of a 60-yr long sediment record from Pelekane Bay was disturbed by tsunamigenic waves from the Tohoku earthquake , and the remainder was likely subject to mixing by winter waves that averaged out geochemical variations. On average, watershed regions with basaltic soils were the predominant source of runoff to the bay over the past 60 years. By linking sediment runoff to geographic regions or features in watersheds, geochemical sourcing can provide insights that allow resource managers to direct runoff mitigation and soil conservation efforts to areas where they will be most effective.

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USGS2019

The 2018 rift eruption and summit collapse of Kilauea Volcano

In 2018, Kīlauea Volcano experienced its largest lower East Rift Zone (LERZ) eruption and caldera collapse in at least 200 years. After collapse of the Pu'u 'Ō'ō vent on 30 April, magma propagated downrift. Eruptive fissures opened in the LERZ on 3 May, eventually extending ~6.8 km. A 4 May earthquake (M6.9) produced ~5 m of fault slip. Lava erupted at rates exceeding 100 m3/s, eventually covering 35.5 km2. The summit magma system partially drained, producing minor explosions and near-daily collapses releasing energy equivalent to M4.7-M5.4 earthquakes. Activity declined rapidly on 4 August. Summit collapse and lava flow volume estimates are roughly equivalent--about 0.8 km3. Careful historical observation and monitoring of Kīlauea enabled successful forecasting of hazardous events.

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USGS2019

Cyclic lava effusion during the 2018 eruption of Kīlauea Volcano

Lava flows present a recurring threat to communities on active volcanoes, and volumetric eruption rate is one of the primary factors controlling flow behavior and hazard. The timescales and driving forces of eruption rate variability, however, remain poorly understood. In 2018, a highly destructive eruption occurred on the lower flank of Kīlauea Volcano, Hawaiʻi, where the primary vent exhibited dramatic cyclic eruption rates on both short (minutes) and long (tens of hours) timescales. We use multiparameter data to show that the short cycles were driven by shallow outgassing, while longer cycles were pressure-driven surges in magma supply triggered by summit caldera collapse events 40 km upslope. The results provide a clear link between eruption rate fluctuations and their driving processes in the magmatic system.

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USGS2019

The tangled tale of Kīlauea’s 2018 eruption as told by geochemical monitoring

Changes in magma chemistry that affect eruptive behavior occur during many volcanic eruptions, but typical analytical techniques are too slow to contribute to hazard monitoring. We used rapid energy-dispersive X-ray fluorescence analysis to measure diagnostic elements in lava samples within a few hours of collection during the 2018 Kīlauea eruption. The geochemical data provided important information for field crews and civil authorities in advance of changing hazards during the eruption. The appearance of hotter magma was recognized several days before the onset of voluminous eruptions of fast-moving flows that destroyed hundreds of homes. We identified, in near-real time, interactions between older, colder, stored magma – including the unexpected eruption of andesite – and hotter magma delivered during dike emplacement.

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USGS2019

Magma reservoir failure and the onset of caldera collapse at Kīlauea volcano in 2018

Caldera-forming eruptions are among Earths most hazardous natural phenomena, yet the architecture of subcaldera magma reservoirs and the conditions that trigger collapse are poorly understood. Observations from the formation of a 0.8cubic kilometer basaltic caldera at Klauea Volcano in 2018 included the draining of an active lava lake, which provided a window into pressure decrease in the reservoir. We show that failure began after <4% of magma was withdrawn from a shallow reservoir beneath the volcanos summit, reducing its internal pressure by ~17 megapascals. Several cubic kilometers of magma were stored in the reservoir, and only a fraction was withdrawn before the end of the eruption. Thus, caldera formation may begin after withdrawal of only small amounts of magma and may end before source reservoirs are completely evacuated.

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USGS2019

Products, processes, and implications of Keanakāko‘i volcanism, Kīlauea Volcano, Hawai‘i

The Keanakāko‘i Tephra offers an exceptional window into the explosive portion of Kīlauea’s recent past. Once thought to be the products of a single eruption, the deposits instead formed through a wide range of pyroclastic activity during an ~300 yr period following the collapse of the modern caldera in ca. 1500 CE. No single shallow conduit or vent system prevailed during this period, and most of the deposits are confined to distinct sectors around the caldera. Vent position shifted abruptly and repeatedly throughout this time period. This combination of circumstances, influenced by prevailing wind direction, led to rapid lateral changes in the stratigraphy. We define and describe 12 units, several of which are subdivided into subunits or beds, and place them in a framework that reflects volcanologic processes as well as temporal succession.

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USGS2019

Geochemical evolution of Keanakāko‘i Tephra, Kīlauea Volcano, Hawai‘i

The Keanakāko‘i Tephra was deposited from 1500 to ca. 1820 CE, when Kīlauea’s magmatic output was ~2% of the average output during historical times (post–1823 CE). The tephra consists of deposits from numerous phreatomagmatic and phreatic eruptions, three episodes of high lava fountains, and one lava. Fresh glass is available from most tephra units. Major elements and trace elements were determined for glass from 49 tephra units and three pretephra lavas. Olivine crystals from 11 high-MgO tephra glasses were also analyzed. These results were compared to compositions from Kīlauea’s historical period to evaluate ~500 yr of Kīlauea geochemical evolution. Keanakāko‘i Tephra glass composition ranged widely (e.g., 3.4–11.2 wt% MgO). The observed large variations in FeO, CaO, TiO 2 , and K 2 O at a given MgO indicate numerous compositionally distinct parental magmas, with the two early nineteenth-century pumice eruptions showing the most diverse compositions. These two magmas were erupted on opposite sides of the caldera and probably tapped different magma bodies. The common occurrence of high-MgO olivine compositions (forsterite [Fo] 88%–89%) in MgO-rich tephra glasses indicates that primitive magma (Mg# 73–74) was routinely supplied to Kīlauea’s summit. Wide ranges and reverse zoning in olivine core compositions from some units show that magma mixing occurred before some eruptions. Modeling of compositional variations within Keanakāko‘i Tephra units using alphaMELTS showed that the most consistent trends for crystal fractionation involved shallow magma (1–2 km), with low water content (0.2 wt% in parental magma) and oxygen fugacity just below the quartz-fayalite-magnetite (QFM) buffer (–0.5 log units). Keanakāko‘i Tephra glasses have lower La/Yb and Nb/Y ratios than historical Kīlauea lavas. Low ratios have been observed during periods of high magma output for historical lava, which is inconsistent with the low magma output at Kīlauea’s summit during 1500–1820 CE. The most likely explanation for this inconsistency is endogenous growth within Kīlauea during this period, following formation of the modern summit caldera. No correlation was found between glass chemistry and eruption style for Keanakāko‘i Tephra deposits. Glass samples from many explosive units have lower Nb/Y and La/Yb ratios compared to glass from high lava-fountain units and historical effusive eruptions. The explosive character of Keanakāko‘i Tephra eruptions was probably caused by interaction of magma with shallow or surface water.

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USGS2019

A new perspective on the 19th century golden pumice deposit of Kilauea volcano

The golden pumice deposit (unit K1) represents one of the latest episodes of Hawaiian fountaining in the Keanakāko‘i Tephra and is the product of the first high fountaining eruption at Kīlauea summit in ~300 yr, since the caldera formed in ca. 1500 CE. We present a new physical characterization of the deposit based on over 200 field sites, all affected by severe erosion, alteration, and silicic encrusting. We detail the deposit geometry, stratigraphic and structural relationships, and componentry to constrain its volume and reconstruct the eruptive sequence. The deposit is then discussed and set against other young episodes of high fountaining at Kīlauea. We interpret the golden pumice as the product of a days-long eruptive sequence with a source located inside a caldera much deeper than that of today. The eruption probably started along a NE-SW–oriented fissure and migrated toward a single vent in the southwestern part of the caldera, where at least two high Hawaiian-style fountains produced a tephra deposit of ~6 × 10 6 m 3 . Stratigraphic contacts reveal that erosion occurred not only between, but also during the fountaining episodes, suggesting heavy rainfall during deposition. Field observations during this study also led to the discovery of the first stratigraphic evidence that the eastern pumice postdates the golden pumice, which contributes to the new definition of the stratigraphy of the Keanakāko‘i Tephra presented in this volume.

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USGS2019

Dikes in the Koaʻe fault system, and the Koaʻe-east rift zone structural grain at Kīlauea Volcano, Hawaii

Two small scoria vents were discovered in the Koa‘e fault system, an extensional regime connecting the east and southwest rift zones of Kīlauea that was previously considered to be noneruptive. The chemical composition of the scoria suggests an early to middle nineteenth-century age. The vents prove that magma can intrude several kilometers into the central part of the Koa‘e fault system from the nearest rift zone, supporting previous seismic and geodetic inferences of intrusions into the Koa‘e fault system in the twentieth century. Geodetic studies for the past 50 yr document widening of the Koa‘e fault system at a time-averaged rate of ~4.5 cm/yr, involving mostly coseismic strains, but also creep and displacement related to dike intrusions. These rates are consistent with a longer-term widening rate for the past ~700 yr calculated from crack widths in a lava flow of about that age. The Koa‘e fault system blends into, and is a structural continuation of, the east rift zone. We interpret the locus of intrusion in the east rift zone to have migrated ~6.5 km SE during the past 100,000–125,000 yr, as estimated from linear extrapolation of measured displacement rates across the Koa‘e fault system and east rift zone. The inception of migration is consistent with the onset of the tholeiitic stage at Kīlauea as interpreted by previous studies. As the rift zone moved away from the summit, a marked curvature in the transport pathway developed in order for the rift zone to maintain its connection to the summit magma reservoir. The migration resulted in development of the SE-trending east rift connector, a term we prefer instead of the upper east rift zone. The connector supplies magma to the ENE-trending rift zone from the summit storage complex but is not itself the site of significant magma storage or eruption. The Koa‘e fault system merges into the southwest rift zone, which has been migrating southeastward for an uncertain period of time. Some magma that enters it passes from the summit reservoir complex through the southwest rift connector (seismic southwest rift zone), analogous to the east rift connector. Both connectors reflect the response of magma-transport pathways to asymmetric volcano spreading away from a relatively fixed summit magma reservoir. The ENE structural grain of the Koa‘e fault system and east rift zone pervades Kīlauea’s entire edifice. Most eruptions take place along this trend. The major exception is the southwest rift zone, which may reflect the stresses of Mauna Loa spreading and the Ka‘ōiki fault system. The dominant ENE grain emphasizes the importance of SSE-directed volcano spreading in controlling most of Kīlauea’s tectonic and eruptive behavior.

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USGS2019

Lava lake thermal pattern classification using self organizing maps and relationships to eruption processes at Kilauea Volcano, Hawaii

Kīlauea Volcano’s active summit lava lake poses hazards to downwind residents and over 1.6 million Hawai‘i Volcanoes National Park visitors each year. The lava lake surface is dynamic; crustal plates separated by incandescent cracks move across the lake as magma circulates below. We hypothesize that these dynamic thermal patterns are related to changes in other volcanic processes, such that sequences of thermal images may provide information about eruption parameters that are sometimes difficult to measure. The ability to learn about current gas emissions and seismic activity from a remote thermal time-lapse camera would be beneficial when conditions are too hazardous for field measurements. We apply a machine learning algorithm called self-organizing maps (SOM) to thermal infrared time-lapse images of the lava lake collected hourly over 23 April – 21 October 2013 (n=4354). The SOM algorithm can take thousands of seemingly different images, each representing the spatial distribution of relative temperature across the lava lake surface, and group them into clusters based on their similarities. We then relate the resulting clusters to sulfur dioxide emissions and seismic tremor to characterize ties between the SOM classification and different emplacement conditions. The SOM classification results are highly sensitive to the normalization method applied to the input images. The standard pixel-by-pixel normalization method yields a cluster of images defined by the highest observed SO2 emission levels, elevated surface temperatures, and a high proportion of cracks between crustal plates. When lava lake surface patterns are isolated by minimizing the effect of temperature variation between images, relationships with seismic tremor activity emerge, revealing an “intense spatter” cluster, characterized by unstable, broken-up crustal plate patterns on the lava lake surface. This proof of concept study provides a basis for extending the SOM classification method to hazard forecasting and real-time volcanic monitoring applications, as well as comparative studies at other lava lakes.

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USGS2019

Communication strategy of the U.S. Geological Survey Hawaiian Volcano Observatory during the lava-flow crisis of 2014–2015, Kilauea Volcano, Hawaii

In 2014–2015, a slow-moving pāhoehoe lava flow from the remote Pu‘u ‘Ō‘ō vent on Kīlauea Volcano advanced 20 km into populated areas of the Puna District on the Island of Hawai‘i. The staff of the U.S. Geological Survey’s (USGS) Hawaiian Volcano Observatory (HVO) mobilized their resources to closely monitor the flow and provide up-to-date information to the Hawai‘i County Civil Defense (HCCD) agency, the public, and the news media. Scientists issued formal USGS notifications about the flow and Kīlauea’s two eruptions, prepared maps and annotated photographs, infrared images, and videos for dissemination online, and wrote weekly “Volcano Watch” articles for local newspapers. They also provided regular briefings for federal, state, and county agency representatives, answered questions during near-daily briefings with local and national media, and offered information through an established lecture series and participation in community emergency preparedness fairs. Noteworthy among the communication activities was a series of public meetings organized by the Hawai‘i County mayor’s office and led by the HCCD administrator. The meetings were a regular forum for many HVO scientists to talk directly and frequently with residents, business owners, elected officials, and other stakeholders about their concerns, the evolving status of the eruptions, and the uncertain prognosis of the flow’s advance and extent. The dialogue was essential for HVO staff to describe their observations and insights about the lava flow’s behavior and to gain credibility with the community during the crisis. This experience suggests that personal engagement with people at risk from future lava flows in Hawai‘i and elsewhere in the world will remain a crucial part of an eruption response, even with greater capability to disseminate warnings and information digitally via the Internet.

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USGS2019

Integrating structure from motion, numerical modelling and field measurements to understand carbonate sediment transport in coral reef canopies

Reef canopies are complex and extremely variable across a range of spatial scales. This variability affects the velocity above as well as within the canopy, and directly impacts the transport of sediment along the bed as well as suspended in the water column. How a canopy affects the transport of sediment is important to understand and predict changes in the position of the adjacent shoreline, particularly as reefs change. In this study, high-resolution seabed complexity models derived from photogrammetry for low roughness and high roughness canopy sites at Moloka’i (Hawai’i) are combined with direct field measurements and three-dimensional numerical modelling to investigate these canopy and sub-canopy impacts on velocity and sediment transport.

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USGS2019

The influence of sea level on incident and infragravity wave-driven sediment dynamics across a fringing coral reef

Coral reefs generate significant volumes of carbonate sediment that becomes the primary source of beach material along many low-latitude shorelines that protect hundreds of millions of people globally. Despite this fact, there is little understanding of the specific processes that transport the carbonate sediment produced on the outer portions of coral reefs to the shoreline, let alone how those processes may be affected by projected sea-level rise. To better constrain the influence of sea-level rise on waves and sediment transport over a fringing coral reef flat, an experiment was conducted across the large fringing reef off the south shore of Moloka’i, Hawai’i, in the summer of 2018. Here we describe the influence of water levels on waves, currents, and the resulting sediment resuspension and fluxes observed during this field effort

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USGS2019

Frequent use of upland habitats by the endangered Hawaiian stilt (Himantopus mexicanus knudseni)

The Hawaiian Stilt, or Ae’o (Himantopus mexicanus knudseni), is an endangered waterbird endemic to the Hawaiian Islands. Loss of suitable wetland habitats due to anthropogenic development is a leading cause for decline, as well as the introduction of non-native predators and invasive wetland plants. This study fitted four Hawaiian Stilts with GPS satellite tags to document their use of wetland and surrounding habitats on Oahu Island. While other Hawaiian waterbirds are largely restricted to wetlands, we detected Hawaiian Stilts using heavily modified upland habitats, including developed areas, undeveloped fields, sports fields, as well as wetland habitats over a 6-month period. Overall, a high use of non-wetland habitat was observed (up to 58%), with significant differences in habitat occupancy among individual stilts and across different times of day. Wetlands were the dominant habitat occupied from morning to early afternoon, but non-wetland habitats were occupied at higher frequencies in the evening and early morning hours. Although only four birds were tracked, the extensive use of non-wetland habitat by these individuals indicates management of non-wetland habitats may be important for the conservation of this subspecies. However, more research is needed to understand how applicable these results are to other stilt popualtions across the Hawaiian Islands, and better understand the potential risks and benefits of these non-wetland habitats to stilt populations.

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USGS2019

Seasonality and prevalence of pollen collected from Hawaiian nectarivorous birds

Hawaiian nectarivorous forest birds play a vital ecological role as pollinators in Hawaiian ecosystems. However, little is known about what nectar resources are utilized by Hawai‘i’s nectarivorous birds, how seasonality influences nectar availability, and how nectar preference differs by bird species. We sampled pollen from the heads of ‘i‘iwi (Drepanis coccinea), ‘apapane (Himatione sanguinea), Hawai‘i ‘amakihi (Chlorodrepanis virens), and the non-native Japanese white-eye (Zosterops japonicas) captured at Hakalau Forest National Wildlife Refuge on Hawai‘i Island. ‘Ōhi‘a (Metrosideros polymorpha) was the most prevalent pollen species, observed throughout the sampling period while other pollen species were more seasonal in occurrence. Consistent with the peak flowering phenology of the plant species, pollen from koa (Acacia koa), māmane (Sophora chrysophylla), and gorse (Ulex europaeus) plant species were more commonly sampled from birds in the winter months, while ‘ōhelo (Vaccinium reticulatum), ‘ākala (Rubus hawaiensis), and blackberry (Rubus argutus) were more prevalent during the spring months. We also found an association between bird species and pollen resources, with ‘i‘iwi and Hawai‘i ‘amakihi having a higher diversity of pollen than ‘apapane and Japanese white-eye, which primarily had just ‘ōhi‘a. These results demonstrate that ‘ōhi‘a is likely the most important nectar resource for Hawai‘i’s nectar feeding birds, but seasonally abundant nectar may be important for some species.

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USGS2019

Screening and biosecurity for White-nose Fungus Pseudogymnoascus destructans (Ascomycota: Pseudeurotiaceae) in Hawai‘i

Introduced pathogens causing emerging infectious diseases (EIDs) are serious contemporary threats to animal, plant, and ecosystem health. The invasive fungus, Pseudogymnoascus destructans , has established populations of European origin in North America, resulting in mass mortality of several hibernating bat species. Extensive monitoring for this pathogen exists in Europe and North America, but limited screening is taking place elsewhere. We report results from cave surveys on Hawai‘i Island. Substrates in 10 lava-tube caves with elevations up to 3,045 m were swabbed providing samples for screening P. destructans . Interior cave air temperatures spanned temperatures suitable for the growth and survival of P. destructans . Using quantitative PCR, all 85 samples tested were negative for the presence of P. destructans . The biology of the Hawaiian hoary bat ( Lasiurus cinereus semotus ) in relation to its unusual use of high elevation caves is discussed because these bats could come into contact with P. destructans should it arrive in Hawai‘i. Large numbers of cave enthusiasts visit Hawaiian caves from across the world after having been inside caves elsewhere including areas with P. destructans . Thus, resource managers in Hawai‘i and other remote areas may want to consider the potential for P. destructans to arrive unintentionally via human activities. Biosecurity measures and periodic screening for P. destructans are especially important in Hawai‘i given the presence of high elevation caves with suitable temperatures for its growth. If P. destructans was introduced to Hawaiian caves, it could affect the local fauna but also act as a source population for colonisations elsewhere.

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USGS2019

Hawaiian hoary bat (Lasiurus cinereus semotus) activity and prey availability at Kaloko-Honokohau National Historical Park

We examined habitat use and foraging activity of the endangered Hawaiian hoary bat (Lasiurus cinereus semotus), as well as nocturnal aerial insect abundance at Kaloko-Honōkohau National Historical Park located in the coastal region of Kailua-Kona, Hawai‘i Island. We evaluated bat activity in two habitat types, wooded shorelines beside brackish water fishponds and xeric lava fields dominated by two invasive plant species: white leadwood (Leucaena leucocephala, Fabaceae), and fountain grass (Cenchrus setaceus, Poaceae). We recorded bat echolocation calls at seven acoustic stations that operated nightly from November 2013 through February 2015. Additionally, three UV light traps were used to collect insects at three locations from dusk to dawn in January, April, July and November 2014. Bat acoustic activity showed seasonal patterns in pulse counts, call-events, feeding buzzes and frequency of occurrence with three major peaks in bat echolocation activity in November–December 2013, April–May 2014, and August–December 2014. Overall, bat acoustic activity was greatest at the shoreline of Kaloko Fishpond. Although there were no significant differences in insect biomass among collection stations, Hawaiian hoary bats use the Park as an important foraging habitat.

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