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Research about Hawaii

Source-linked reports with geographic coverage including Hawaii.

At least 631 records · Page 35Linked to original sources
USGS2011

Shallow degassing events as a trigger for very-long-period seismicity at Kilauea Volcano, Hawaii

The first eruptive activity at Kīlauea Volcano’s summit in 25 years began in March 2008 with the opening of a 35-m-wide vent in Halema‘uma‘u crater. The new activity has produced prominent very-long-period (VLP) signals corresponding with two new behaviors: episodic tremor bursts and small explosive events, both of which represent degassing events from the top of the lava column. Previous work has shown that VLP seismicity has long been present at Kīlauea’s summit, and is sourced approximately 1 km below Halema‘uma‘u. By integrating video observations, infrasound and seismic data, we show that the onset of the large VLP signals occurs within several seconds of the onset of the degassing events. This timing indicates that the VLP is caused by forces—sourced at or very near the lava free surface due to degassing—transmitted down the magma column and coupling to the surrounding rock at 1 km depth.

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USGS2011

Spatiotemporal evolution of dike opening and décollement slip at Kīlauea Volcano, Hawai'i

Rapid changes in ground tilt and GPS positions on Kīlauea Volcano, Hawai'i, are interpreted as resulting from a shallow, two‐segment dike intrusion into the east rift zone that began at 1217 UTC (0217 HST) on 17 June 2007 and lasted almost 3 days. As a result of the intrusion, a very small volume of basalt (about 1500 m 3 ) erupted on 19 June. Northward tilt at a coastal tiltmeter, subsidence of south flank GPS sites, southeastward displacements at southwestern flank GPS sites, and a swarm of flank earthquakes suggest that a slow slip event occurred on the décollement beneath Kīlauea's south flank concurrent with the rift intrusion. We use 4 min GPS positions that include estimates of time‐dependent tropospheric gradients and ground tilt data to study the spatial and temporal relationships between the two inferred shallow, steeply dipping dike segments extending from the surface to about 2 km depth and décollement slip at 8 km depth. We invert for the temporal evolution of distributed dike opening and décollement slip in independent inversions at each time step using a nonnegative least squares algorithm. On the basis of these inversions, the intrusion occurred in two stages that correspond spatially and temporally with concentrated rift zone seismicity. The dike opening began on the western of the two segments before jumping to the eastern segment, where the majority of opening accumulated. Dike opening preceded the start of décollement slip at an 84% confidence level; the latter is indicated by the onset of northward tilt of a coastal tiltmeter. Displacements at southwest flank GPS sites began about 18 h later and are interpreted as resulting from slow slip on the southwestern flank. Additional constraints on the evolution of the intrusion and décollement slip come from inversion of an Envisat interferogram that spans the intrusion until 0822 UTC on 18 June 2007, combined with GPS and tilt data. This inversion shows that up to 0822 UTC on 18 June, décollement slip is only required in a limited region offshore of Ka'ena Point. A similar inversion of the complete event, which includes GPS and tilt data up to 21 June and a second Envisat interferogram spanning the complete intrusion until 21 June, shows décollement slip spread westward across the south flank. This may suggest westward migration of the décollement slip as the event progressed.

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USGS2011

Cyclic spattering, seismic tremor, and surface fluctuation within a perched lava channel, Kilauea Volcano

In late 2007, a perched lava channel, built up to 45 m above the preexisting surface, developed during the ongoing eruption near Pu‘u ‘Ō‘ō cone on Kīlauea Volcano’s east rift zone. The lava channel was segmented into four pools extending over a total of 1.4 km. From late October to mid-December, a cyclic behavior, consisting of steady lava level rise terminated by vigorous spattering and an abrupt drop in lava level, was commonly observed in pool 1. We use geologic observations, video, time-lapse camera images, and seismicity to characterize and understand this cyclic behavior. Spattering episodes occurred at intervals of 40–100 min during peak activity and involved small (5–10-m-high) fountains limited to the margins of the pool. Most spattering episodes had fountains which migrated downchannel. Each spattering episode was associated with a rapid lava level drop of about 1 m, which was concurrent with a conspicuous cigar-shaped tremor burst with peak frequencies of 4–5 Hz. We interpret this cyclic behavior to be gas pistoning, and this is the first documented instance of gas pistoning in lava well away from the deeper conduit. Our observations and data indicate that the gas pistoning was driven by gas accumulation beneath the visco-elastic component of the surface crust, contrary to other studies which attribute similar behavior to the periodic rise of gas slugs. The gas piston events typically had a gas mass of about 2,500 kg (similar to the explosions at Stromboli), with gas accumulation and release rates of about 1.1 and 5.7 kg s −1 , respectively. The time-averaged gas output rate of the gas pistoning events accounted for about 1–2% of the total gas output rate of the east rift zone eruption.

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USGS2011

Diffusion-driven magnesium and iron isotope fractionation in Hawaiian olivine

Diffusion plays an important role in Earth sciences to estimate the timescales of geological processes such as erosion, sediment burial, and magma cooling. In igneous systems, these diffusive processes are recorded in the form of crystal zoning. However, meaningful interpretation of these signatures is often hampered by the fact that they cannot be unambiguously ascribed to a single process (e.g., magmatic fractionation, diffusion limited transport in the crystal or in the liquid). Here we show that Mg and Fe isotope fractionations in olivine crystals can be used to trace diffusive processes in magmatic systems. Over sixty olivine fragments from Hawaiian basalts show isotopically fractionated Mg and Fe relative to basalts worldwide, with up to 0.4‰ variation in 26 Mg/ 24 Mg ratios and 1.6‰ variation in 56 Fe/ 54 Fe ratios. The linearly and negatively correlated Mg and Fe isotopic compositions [i.e., δ 56 Fe = (− 3.3 ± 0.3) × δ 26 Mg], co-variations of Mg and Fe isotopic compositions with Fe/Mg ratios of olivine fragments, and modeling results based on Mg and Fe elemental profiles demonstrate the coupled Mg and Fe isotope fractionation to be a manifestation of Mg–Fe inter-diffusion in zoned olivines during magmatic differentiation. This characteristic can be used to constrain the nature of mineral zoning in igneous and metamorphic rocks, and hence determine the residence times of crystals in magmas, the composition of primary melts, and the duration of metamorphic events. With improvements in methodology, in situ isotope mapping will become an essential tool of petrology to identify diffusion in crystals.

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USGS2011

Pigeonholing pyroclasts: Insights from the 19 March 2008 explosive eruption of Kīlauea volcano

We think, conventionally, of volcanic explosive eruptions as being triggered in one of two ways: by release and expansion of volatiles dissolved in the ejected magma (magmatic explosions) or by transfer of heat from magma into an external source of water (phreatic or phreatomagmatic explosions). We document here an event where neither magma nor an external water source was involved in explosive activity at Kīlauea. Instead, the eruption was powered by the expansion of decoupled magmatic volatiles released from deeper magma, which was not ejected by the eruption, and the trigger was a collapse of near-surface wall rocks that then momentarily blocked that volatile flux. Mapping of the advected fall deposit a day after this eruption has highlighted the difficulty of constraining deposit edges from unobserved or prehistoric eruptions of all magnitudes. Our results suggest that the dispersal area of advected fall deposits could be miscalculated by up to 30% of the total, raising issues for accurate hazard zoning and assessment. Eruptions of this type challenge existing classification schemes for pyroclastic deposits and explosive eruptions and, in the past, have probably been interpreted as phreatic explosions, where the eruptive mechanism has been assumed to involve flashing of groundwater to steam.

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USGS2011

The dynamics, transmission, and population impacts of avian malaria in native hawaiian birds: A modeling approach

We developed an epidemiological model of avian malaria ( Plasmodium relictum ) across an altitudinal gradient on the island of Hawaii that includes the dynamics of the host, vector, and parasite. This introduced mosquito‐borne disease is hypothesized to have contributed to extinctions and major shifts in the altitudinal distribution of highly susceptible native forest birds. Our goal was to better understand how biotic and abiotic factors influence the intensity of malaria transmission and impact on susceptible populations of native Hawaiian forest birds. Our model illustrates key patterns in the malaria–forest bird system: high malaria transmission in low‐elevation forests with minor seasonal or annual variation in infection; episodic transmission in mid‐elevation forests with site‐to‐site, seasonal, and annual variation depending on mosquito dynamics; and disease refugia in high‐elevation forests with only slight risk of infection during summer. These infection patterns are driven by temperature and rainfall effects on parasite incubation period and mosquito dynamics across an elevational gradient and the availability of larval habitat, especially in mid‐elevation forests. The results from our model suggest that disease is likely a key factor in causing population decline or restricting the distribution of many susceptible Hawaiian species and preventing the recovery of other vulnerable species. The model also provides a framework for the evaluation of factors influencing disease transmission and alternative disease control programs, and to evaluate the impact of climate change on disease cycles and bird populations.

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USGS2011

Potential effects of roadside dry wells on groundwater quality on the Island of Hawai'i — Assessment using numerical groundwater models

Widespread use of dry wells to dispose of roadside runoff has raised concern about the potential effects on the quality of groundwater on the Island of Hawai‘i. This study used semi-generic numerical models of groundwater flow and contaminant transport to assess the potential effect of dry wells on groundwater quality on the Island of Hawai‘i. The semi-generic models are generalized numerical groundwater-flow and solute-transport models that have a range of aquifer properties and regional groundwater gradients that are characteristic for the island. Several semi-generic models were created to study the effect of dry wells in different hydrogeologic conditions, such as different unsaturated-zone thicknesses or different aquifer characteristics. Results indicate that mixing of contaminated water from the surface with contaminant-free water in the saturated aquifer immediately reduces the contaminant concentration. The amount the concentration is reduced depends on the hydraulic properties of the aquifer in a given area, the thickness of the unsaturated zone, and whether the infiltration is focused in a small area of a dry well or spread naturally over a larger area. Model simulations indicate that focusing infiltration of contaminated runoff through a dry well can substantially increase contaminant concentrations in the underlying saturated aquifer relative to infiltration under natural conditions. Simulated concentrations directly beneath a dry well were nearly 8 times higher than the simulated concentrations directly beneath a broad infiltration area representing the natural condition. Where dry wells are present, contaminant concentrations in the underlying saturated aquifer are lower when the unsaturated zone is thicker and higher when the unsaturated zone is thinner. Contaminant concentrations decline quickly as the contaminant plume migrates, with the regional groundwater flow, away from the dry well. The differences among concentrations resulting from the various unsaturated-zone thicknesses also diminish with distance from the dry well. At a horizontal distance of about 700 ft downgradient from the dry well, all simulated maximum concentrations were less than 1 percent of the concentration in the infiltration water; at about 0.5 mi downgradient from the dry well, all simulated concentrations were equal to or less than 0.1 percent. Actual concentrations may be even lower than indicated by the models because of processes such as decay and reaction that were not simulated. Hydrologic and geologic differences from one location to the next also affect contaminant concentrations—simulations using models with properties representative of aquifers in the Hilo area resulted in lower overall concentrations than models with properties representative of aquifers in the Kona area. Results from this study can be used to assess how contaminants entering a dry well may affect receiving waters in a variety of situations on the Island of Hawai‘i. Better assessment would be obtained by using results from models having the most similar conditions (such as climate, hydraulic properties, regional groundwater gradient) to the dry well in question. The results of this study can help determine which dry wells are likely to have the greatest effect on nearby receiving waters and where more specific data and analyses may be needed.

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USGS2011

Design of forest bird monitoring for strategic habitat conservation on Kaua'i Island, Hawai'i

This report was commissioned by the U.S. Fish and Wildlife Service (USFWS). The purpose was to develop a monitoring program for Kaua`i forest birds in the USFWS Strategic Habitat Conservation and adaptive management frameworks. Monitoring within those frameworks is a tool to assess resource responses to management and conservation actions, and through an iterative learning process improve our understanding of species recovery, effective management, and knowledge gaps. This report provides only the monitoring component of both frameworks, and we apply the monitoring program to the East Alaka`i Protective Fence Project. The East Alaka`i Protective Fence Project is a joint project by the USFWS, State of Hawai`i Division of Forest and Wildlife, Kaua`i Watershed Alliance, and The Nature Conservancy to restore and preserve an 809 ha area of native forest bird habitat through fencing, and ungulate and weed control. The primary purpose of the project is to restore and preserve the habitat that will in turn support abundant and resilient bird populations. This report contains: A monitoring program specifically developed to track bird distribution, density and demography, and habitat for the East Alaka`i Protective Fence Project; A review of the Kaua`i forest bird surveys; A description of the current status and trends of Kaua`i forest birds; An assessment and evaluation of the current surveys; A monitoring program developed to sample bird distribution, density and demography, and habitat at three general levels of spatial scale. Without the management components described in the East Alaka`i Protective Fence Project and the Revised Recovery Plan for Hawaiian Forest Birds (USFWS 2006) the bird monitoring recommended in this report is little better than surveillance (i.e., monitoring without a link to management). If, however, the proposed management actions are implemented in conjunction with the recommended bird monitoring, then this monitoring program will identify population changes in a timely manner and facilitate identification of the proximate causes of population changes.

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USGS2011

Survey of invasive ants at Hakalau Forest National Wildlife Refuge

We conducted a survey for invasive ants at Hakalau Forest National Wildlife Refuge, Hawai‘i Island, during 2009–2010 to evaluate potential threats to native arthropod communities and food webs. The focal area of the survey was the upper portion of the Hakalau Unit of the refuge, where native forest was being restored in abandoned cattle pastures. This area, between 1575 and 1940 m elevations, contained much alien kikuyu grass (Pennisetum clandestinum), but koa (Acacia koa) trees and other native species that were planted in the past 20 years were rapidly filling in the pasture. We surveyed for ants at predetermined points along roads, fences, and corridors of planted koa. Sampling methods primarily consisted of hand searching and pitfall traps, but bait cards were used additionally in some instances. Our results indicated that a single species, Cardiocondyla kagutsuchi, was widespread across the upper portion of the refuge. Cardiocondyla kagutsuchi seemed absent, or at least rare, in areas of tall, dense grass. Due to the undulating topography of the area, however, the dense grass cover was interspersed with outcroppings of exposed, gravelly soil. Presumably due to warming by the sun, many of the outcropped habitats supported colonies of C. kagutsuchi. We did not detect ants in the old-growth forest below the abandoned pastures, presumably because microhabitat conditions under the forest canopy were unsuitable. Although ecological impacts of C. kagutsuchi have not been reported, they may be limited by the small size of the ant, the relatively small size of colonies, and the apparent preference of the ant for disturbed areas that are dominated by alien species. Notably, our survey of Keanakolu-Mana Road between the Observatory Road (John A. Burns Way) and the town of Waimea detected a population of Argentine ants (Linepithema humile) approximately 5.1 km north of the Maulua Section of the refuge. We also surveyed for ants on the Kona Forest Unit of the refuge. This small survey focused on approximately 14 km of roads located below about 1600 m elevation. We found two species, Solenopsis papuana and Nylanderia bourbonica. Solenopsis papuana was more widespread, being found along the southern, northern, and western boundaries, while N. bourbonica was detected only at 790 m elevation on the southern boundary. Of the two species, S. papuana seemed more likely to affect native arthropod communities due to its tendency to form relatively large, aggressive colonies and its ability to inhabit intact mesic and wet forests below 1100 m elevation. In contrast, the restriction of N. bourbonica to disturbed habitats indicated a reduced threat to native arthropod communities. Our results on the Kona Forest Unit corroborated those of a study conducted during 1999–2000, although the earlier study was more intensive over time and yielded small numbers of two additional species, Cardiocondyla wroughtonii and Tetramorium bicarinatum, both of which were detected below 792 m elevation along the southern boundary.

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USGS2011

Rare and endangered species of Hawai`i Volcanoes National Park; endangered, threatened, and rare animal, plant, and community handbook

Introduction Hawai`i Volcanoes National Park (HAVO) is the largest area in the State of Hawai`i protected for its geology and landscapes and its native flora and fauna. The park covers approximately 135,000 hectares or 333,000 acres in all. These lands stretch from the seacoast of Kīlauea Volcano to far above timberline on the summit of Mauna Loa (Figure 1). This vast area includes expanses of forests, woodlands, shrublands, and barren lava flows that represent an array of native ecosystems. Contained within these communities are a great many species of rare animals and plants, most of them unique to the island of Hawai`i, and some of them surviving only in the park. These are the biological treasures of Hawai`i Volcanoes National Park. Our book is a guide to all animal and plant species in HAVO that are specially recognized as endangered species in the general sense. (The official designations at four levels and the unofficial designation of species of concern are explained later.) There are 23 such animal species and 71 plant species covered in the handbook, including six species planted in HAVO but not naturally occurring. In addition, we describe seven rare communities. In some cases, HAVO offers the best opportunity to save these species and communities from extinction. Increasingly, the park has attempted to restore rare populations by conducting surveys to locate them, controlling threats such as feral livestock, and bolstering existing populations or creating new ones by planting nursery stock. To aid such efforts, our original intent was to publish an identification guide for researchers and field management personnel. Particularly, we wanted to familiarize the reader with the many rare plant species which otherwise are known mainly from the technical literature. Because we soon came to realize that this handbook would be useful to a much larger, general readership, our aim is to make this information available to anyone interested in endangered animals and plants at Hawai`i Volcanoes National Park.

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USGS2011

Keeping Hawai’i’s forest birds one step ahead of avian diseases in a warming world: a focus on Hakalau Forest National Wildlife Refuge. A case study from the National Conservation and Training Center Structured Decision Making Workshop

This report is a product of a one-week workshop on using Structured Decision Making to identify and prioritize conservation actions to address the threat of climate change on Hawaii‟s native forest bird community. Specifically, t his report addresses the issue of global warming ‟s likely role in increasing disease prevalence in upper elevation forests of Hawaii, negatively impacting native bird populations susceptible to the disease but currently disease - free because of the cooler temperatures at high elevations.

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USGS2011

Efficacy of fipronil for control of yellowjacket wasps in Hawaii Volcanoes National Park

The western yellowjacket wasp (Vespula pensylvanica) invaded Hawai`i’s national parks and refuges following its spread throughout the islands in the late 1970s. The endemic arthropod fauna of Hawai`i is thought to be especially vulnerable to these predacious social Hymenoptera, and methods of wasp control have been a priority for conservation biology in Hawai`i. The efficacy of the insecticide fipronil mixed with minced canned chicken meat for suppression of yellowjacket populations was evaluated in five experimental field trials in Hawai`i Volcanoes National Park between 1999 and 2005. Populations of Vespula were monitored in replicate twoto four- hectare study areas in mesic montane and seasonal submontane forests, before and after application of chicken bait, with and without 0.1% fipronil, and in treatment and nontreatment areas. The bait was applied in hanging bait stations for two to three days. The response of yellowjacket wasp populations was measured using at least three different metrics of abundance including instantaneous counts of wasps at bait stations, wasp traffic rates at Vespula nests, as well as heptyl butyrate trap and/or malaise trap catches in the study areas. All indices of wasp abundance exhibited significant reductions in sites treated with fipronil compared with non-treatment sites with the exception of malaise trapping, where only a limited number of traps were available to be deployed. Wasp traffic ceased at all Vespula nests in sites treated with fipronil within a month after baiting in four of the five trials. The only trial where fipronil failed to terminate yellowjacket nest activity occurred late in the fall when wasps switch from feeding on protein to carbohydrate foods. Based on these data, 0.1% fipronil in chicken bait appears to be an effective tool for suppressing local Vespula yellowjacket populations in the park and other natural areas during the period of peak wasp activity in the summer and early fall months.

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USGS2011

Recent plant eradications on the islands of Maui County, Hawai'i

The state of Hawai'i (USA) has few regulations to limit plant introductions. A network of interagency islandbased invasive species committees has evolved over the past decade to address this vulnerability, with the aim of stopping invasions before they threaten natural areas. On Maui, Moloka‘i, and Lāna‘i, which comprise three of the four islands of Maui County, single-island eradications have been achieved for 12 plant species and eradication is likely imminent for an additional eight species. The islands vary in size, population, and land ownership. We explore the relative importance of those variables in achieving successful eradications along with target species selection, detection strategies, and public support

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USGS2011

Hydrogeology of the Hawaiian islands

Volcanic-rock aquifers are the most extensive and productive aquifers in the Hawaiian Islands. These aquifers contain different types of groundwater systems depending on the geologic setting in which they occur. The most common groundwater systems include coastal freshwater-lens systems in the dike-free flanks of the volcanoes and dike-impounded systems within the dike-intruded areas of the volcanoes. In some areas, a thick (hundreds of meters) freshwater lens may develop because of the presence of a coastal confining unit, or caprock, that impedes the discharge of groundwater from the volcanic-rock aquifer, or because the permeability of the volcanic rocks forming the aquifer is low. In other areas with low groundwater-recharge rates and that lack a caprock, the freshwater lens may be thin or brackish water may exist immediately below the water table. Dike-impounded groundwater systems commonly have high water levels (hundreds of meters above sea level) and contribute to the base flow of streams where the water table intersects the stream. Recent numerical modeling studies have enhanced the conceptual understanding of groundwater systems in the Hawaiian Islands.

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USGS2011

Weeds of Hawaii’s lands devoted to watershed protection and biodiversity conservation: Role of biological control as the missing piece in an integrated pest management strategy

Despite Hawaii’s reputation as an extinction icon, significant biological resources remain, especially in watersheds, natural areas, and specialized edaphic sites (e.g., lava dry forest, coastal). While direct habitat destruction by humans continues, human-facilitated biological invaders are currently the primary agents of continuing degradation. The ability of invasive plants to have prolific seed production, efficient dispersal systems, and to become established in dense vegetation, complicated by Hawaii’s rugged topography, appears to render mechanical and chemical control as mere holding actions. Costly, ‘environmentally unfriendly’, and often ineffective, strategies using chemical and mechanical control on a large scale, despite the most valiant of efforts, can be viewed simply as attempts to buy time. Without increased levels of safely tested biological control, the seemingly inevitable result is the landscape level transformation of native forests, with potentially catastrophic consequences to cultural, biological, water, and economic resources. Increased levels of effective biological control for certain intractable invasive species appear to comprise a conspicuous ‘missing piece’ in our efforts to protect Hawaiian watersheds and other conservation lands.

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USGS2011

The history of mammal eradications in Hawai`i and the United States associated islands of the Central Pacific

Many eradications of mammal taxa have been accomplished on United States associated islands of the Central Pacific, beginning in 1910. Commonly eradicated species are rabbits ( Oryctolagus cuniculus ), rats ( Rattus spp.), feral cats ( Felis catus ), and several feral ungulates from smaller islands and fenced natural areas on larger Hawaiian Islands. Vegetation and avifauna have demonstrated dramatic recovery as a direct result of eradications. Techniques of worldwide significance, including the Judas goat method, were refined during these actions. The land area from which ungulates have been eradicated on large Hawaiian Islands is now greater than the total land area of some smaller Hawaiian Islands. Large multi-tenure islands present the greatest challenge to eradication because of conflicting societal interests regarding introduced mammals, mainly sustained-yield hunting. The difficulty of preventing reinvasion poses a persistent threat after eradication, particularly for feral pigs ( Sus scrofa ) on multi-tenure islands. Larger areas and more challenging species are now under consideration for eradication. The recovery of endangered Hawaiian birds may depend on the creation of large predator-proof exclosures on some of the larger islands. Large scale eradications of small Indian mongooses ( Herpestes auropunctatus ) would be beneficial to ground-nesting birds such as nēnē ( Branta sandvicensis ), but this has been achieved only in small exclosures.

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USGS2010

Eruptions of Hawaiian volcanoes—Past, present, and future

Viewing an erupting volcano is a memorable experience, one that has inspired fear, superstition, worship, curiosity, and fascination since before the dawn of civilization. In modern times, volcanic phenomena have attracted intense scientific interest because they provide the key to understanding processes that have created and shaped more than 80 percent of the Earth’s surface. The active Hawaiian volcanoes have received special attention worldwide because of their frequent spectacular eruptions, which often can be viewed and studied with relative ease and safety. In January 1987, the U.S. Geological Survey Hawaiian Volcano Observatory (HVO), then located on the caldera rim of Kīlauea, celebrated its 75th anniversary. To honor this anniversary, the U.S. Geological Survey (USGS) published Professional Paper 1350 , a comprehensive summary of the many studies on Hawaiian volcanism by USGS and other scientists through the mid-1980s. Drawing from the wealth of data contained in that volume, the USGS also published in 1987 the original edition of this general-interest booklet, focusing on selected aspects of the eruptive history, style, and products of two of the State of Hawaii’s active volcanoes—Kīlauea and Mauna Loa. A second edition of the booklet was published in 2010 to commemorate the Centennial of HVO (which occurred in January 2012), summarizing abundant new information gained since the January 1983 onset of Kīlauea’s middle East Rift Zone eruption at Pu‘u‘ō‘ō and the March 2008 beginning of Kīlauea’s summit lava-lake activity within Halema‘uma‘u. In this third edition, we include highlights from Kīlauea’s subsequent activity, including the 2018 eruption in the lower East Rift Zone—the largest and most destructive in at least 200 years—and associated summit-collapse events, the eruptions at Kīlauea’s summit since 2018, and the 2022 eruption of Mauna Loa, which occurred after 38 years of quiescence. It also considers new data leading to an improved history of Kīlauea’s explosive activity in the recent geologic past. This general-interest booklet is a companion to the one on Mount St. Helens volcano (southwestern Washington) first published in 1984, revised in 1990. Together, these publications illustrate the contrast between the two main types of volcanoes: shield volcanoes, such as those in the State of Hawaii, which generally are nonexplosive to weakly explosive; and composite volcanoes, such as Mount St. Helens in the Cascade Range, which generally erupt explosively.

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