Search USGS⌕ Search

Geology topics

Research about Hawai'i

Source-linked reports with geographic coverage including Hawai'i.

At least 37 records · Page 2Linked to original sources
USGS2021

Early growth and ecophysiological responses of Koa (Acacia koa A. Gray) seedlings to reduced water and phosphorus

Sites in need of restoration typically have one or more environmental factors that limit seedling establishment. Identifying ecophysiological responses to environmental stressors can provide important insights into mitigating measures that would allow seedlings to overcome such constraints to survival. Koa ( Acacia koa A. Gray) is a nitrogen-fixing tree species endemic to Hawaiʻi that is highly valued in restoring degraded forest ecosystems, which are often limited in available water and phosphorus. This study examined how koa seedlings respond to conditions of reduced water (65 W) and no phosphorus (0P). After 17 weeks, seedlings subjected to 65 W or 0P accumulated less biomass, smaller root-collar diameters, and lower nitrogen and phosphorus contents. Combined reductions in water and P resulted in seedlings with increased root to shoot dry biomass and shorter shoots. Seedlings subjected to 65 W also had lower instantaneous rates of CO 2 assimilation, but higher instantaneous water-use efficiencies following irrigation, suggesting that koa responds to water deficits by decreasing water loss via reduced stomatal conductance. Seedlings subjected to 0P had similar rates of CO 2 assimilation relative to those grown with adequate P, suggesting that koa is able to employ strategies to avoid physiological impairment from conditions of inadequate P. Future research should assess whether subjecting koa seedlings to reduced water before planting on water-limited sites cues increased drought resistance and whether uptake and storage of P by seedlings in the nursery better supports growth following outplanting, particularly on sites with anticipated low plant-available water.

Hawai'i↗
USGS2020

Ambrosia beetle (Coleoptera: Curculionidae) communities and frass production in ʻŌhiʻa (Myrtales: Myrtaceae) infected with Ceratocystis (Microascales: Ceratocystidaceae) fungi responsible for Rapid ʻŌhiʻa Death

Rapid ʻŌhiʻa Death (ROD) is a deadly disease that is threatening the native Hawaiian keystone tree species, ʻōhiʻa lehua ( Metrosideros polymorpha Gaudich). Ambrosia beetles (Curculionidae: Scolytinae) and their frass are hypothesized to play a major role in the spread of ROD, although their ecological niches and frass production within trees and across the landscape are not well understood. We characterized the beetle communities and associated frass production from bolts (tree stem sections) representative of entire individual ʻōhiʻa trees from multiple locations across Hawaiʻi Island by rearing beetles and testing their frass for viable ROD-causing fungi. Additionally, we estimated frass production for three beetle species by weighing their frass over time. We found that Xyleborinus saxesenii (Ratzburg), Xyleborus affinis Eichhoff, Xyleborus ferrugineus (Fabricius), Xyleborus perforans (Wollaston), and Xyleborus simillimus Perkins were commonly found on ROD-infected ʻōhiʻa and each produced frass containing viable Ceratocystis propagules. The Hawaiʻi Island endemic beetle and the only native ambrosia beetle associated with ʻōhiʻa, X. simillimus , was limited to high elevations and appeared to utilize similar tree heights or niche dimensions as the invasive X. ferrugineus . Viable Ceratocystis propagules expelled in frass were found throughout entire tree bole sections as high as 13 m. Additionally, we found that X. ferrugineus produced over 4× more frass than X. simillimus . Our results indicate the ambrosia beetle community and their frass play an important role in the ROD pathosystem. This information may help with the development and implementation of management strategies to control the spread of the disease.

Hawaii↗
USGS2020

Forest bird trends within Haleakala National Park

In 2017, the comprehensive east Maui bird surveys allowed for an update in status and evaluation of trends in bird populations within Haleakalā National Park. This report describes a finer-scale analysis of the park lands, distinguishing between the upper Kīpahulu Valley plus adjacent high-elevation areas compared to the rest of the park. I report abundance estimates and assess trends for six native and three non-native bird species within the park. Overall abundance estimates are consistent with those in previous reports, but there is some evidence for different densities between the two areas of the park, and relative densities of some species may vary from survey to survey. With two possible exceptions (native ‘apapane and non-native red-billed leiothrix), recent trends indicate that bird populations are in decline.

Hawai'i↗
USGS2020

Habitat suitability and ecological associations of two non-native ungulate species on the Hawaiian island of Lanai

The ability to effectively manage game species for specific conservation objectives is often limited by the scientific understanding of their distribution and abundance. This is especially true in Hawai‘i where introduced game mammals are poorly studied and have low value relative to native species in other states. We modeled the habitat suitability and ecological associations of European mouflon sheep (“mouflon”; Ovis musimon ) and axis deer ( Axis axis ) on the island of Lāna‘i using intensive aerial survey and environmental data that included climate, vegetation, and topographic variables. We conducted diagnostic tests on a suite of primarily categorical predictors and determined most were highly correlated. We therefore developed a suite of other spatial predictor layers with continuous variables. We tested several modeling approaches but settled on generalized linear models (GLM) and random GLMs because they could account for group size of animals and were based on curvilinear responses of each species to environmental variability. Both mammal species were habitat generalists showing little affinity to particular plant species or communities. Continuous predictors associated with plant productivity such as mean annual precipitation, normalized difference vegetation index (NDVI), and cloud cover were important explanatory factors in a GLM of axis deer and a random GLM of mouflon habitat suitability. The presence of axis deer was also an important explanatory predictor for mouflon distribution, but deer were not influenced by mouflon distribution, indicating asymmetrical competition. Consequently, mouflon were restricted to lower elevation arid and very dry slopes, whereas axis deer were more broadly distributed throughout other upland environments of the island, but avoided steep terrain. Findings indicate that removal of a substantial portion of the more abundant axis deer population may lead to an increase in abundance and distribution of mouflon without containment. Resulting spatial models of game mammal habitat suitability will be employed to inform land use prioritization analyses and to help resolve long-standing conflicts between native species conservation and sustained-yield hunting.

Hawai'i↗
USGS2019

Organic geochemical investigation of far‐field tsunami deposits of the Kahana Valley, O'ahu, Hawai'i

Far‐field tsunami deposits observed in the Kahana Valley, O'ahu, Hawai'i (USA), were investigated for their organic‐geochemical content. During short high‐energy events, (tsunamis and storms) organic and chemical components are transported with sediment from marine to terrestrial areas. This study investigates the use of anthropogenic based organic geochemical compounds (such as polycyclic aromatic hydrocarbons, pesticides and organochlorides) as a means to identify tsunami deposits. Samples were processed by solid‐liquid extraction and analyzed using gas chromatography–mass spectrometry. A total of 21 anthropogenic marker compounds were identified, of which 11 compounds were selected for detailed analysis. Although the tsunami deposits pre‐date industrial activity in Hawaii by several hundred years, distinct changes were found in the concentrations of anthropogenic marker compounds between sandy tsunami deposits and the surrounding mud/peat layers, which may help in identifying tsunami deposits within cores. As expected, low overall concentrations of anthropogenic markers and pollutants were observed due to the lack of industrial input‐sources and little anthropogenic environmental impact at the study site. This geochemical characterization of tsunami deposits shows that anthropogenic markers have significant potential as another high‐resolution, multi‐proxy method for identifying tsunamis in the sedimentary record.

Hawai'i↗
USGS2019

Eruption and fountaining dynamics of selected 1985–1986 high fountaining episodes at Kīlauea volcano, Hawai'i, from quantitative vesicle microtexture analysis

Tephra from the early Hawaiian fountaining episodes of the ongoing eruption of Pu'u 'Ō'ō in the East Rift Zone (ERZ) of Kīlauea provides an opportunity to study the vesicle microtextures of pyroclasts erupted from a single vent over a prolonged period of time. We report the results of microtextural analysis of pyroclasts from five of Pu'u 'Ō'ō's high (>200 m) Hawaiian fountaining episodes (episodes 32, 37, 40, 44 and 45) erupted during 1985–1986. This analysis was carried out to constrain the parameters that led to large variations in fountain height at Pu'u 'Ō'o, and the extent to which pyroclast residence times in the fountain modified microtextures. Our results confirm the finding of Stovall et al., 2011 , Stovall et al., 2012 that pyroclasts from a single Hawaiian fountain can vary greatly in texture (from bubbly to foamy), and have vesicle volume densities (N m v ) and vesicle to melt ratios (V G /V L ) that vary by an order of magnitude. This range in vesicle texture and population is due to extensive growth and coalescence of vesicles within the fountain after fragmentation. Only one pyroclast from four of five episodes was found to have textures interpreted as indicative of the vesicle population near the moment of fragmentation: bubbly texture, high density (typically >500 kg m −3 ), high N m v (2.2 × 10 6 to 4.4 × 10 6 ), and low V G /V L of 2.06 to 4.65. We demonstrate a linear correlation between Δ(V G /V L ) and peak fountain height across a range of Hawaiian fountains from Kilauea. This correlation could be used to infer peak heights of unobserved Hawaiian fountaining eruptions after further testing using well-recorded events.

Hawai'i↗
USGS2018

The Puʻu ʻŌʻō eruption of Kīlauea Volcano, Hawai‘i—Episode 21 through early episode 48, June 1984–April 1987

The Pu‘u ‘Ō‘ō eruption from the middle East Rift Zone of Kīlauea Volcano began in January 1983 with intermittent activity along several fissures. By June 1983, the eruption had localized at the Pu‘u ‘Ō‘ō vent and the activity settled into an increasingly regular pattern of brief eruptive episodes characterized by high lava fountains. The first 18 months of the eruption (episodes 1–20) are chronicled in previous publications. In the two years following episode 20, Pu‘u ‘Ō‘ō produced another 27 high-fountaining episodes. Episodes 21–47 lasted an average of 12.9 hours and were separated by inter-episode periods averaging 26.5 days. The lava fountains, which reached as high as 510 meters (m), fed lava flows (mostly channelized ʻaʻā) that brought the total area covered by the eruption to 40 square kilometers (km 2 ) by the end of episode 47. Flow thickness measurements obtained for episodes 21–40 averaged 3.4 m; lava volumes for episodes 21–47 averaged 8.0×10 6 m 3 per episode (including the 16-day fissure outbreak of episode 35). The Pu‘u ‘Ō‘ō cone—a composite of pyroclastic material and lava flows—reached its maximum height of 255 m above the pre-eruption surface during episode 43 and maintained that height through episode 47. Short-lived eruptive fissures and vents at or near the base of the Pu‘u ‘Ō‘ō cone accompanied episodes 21, 25, 29, 35, 39, and 44. Episode 35 was unusual in that a fissure on the uprift flank of the cone erupted early in the episode, and then reactivated and extended 2.5 km uprift after the high fountaining was over and erupted for the next 16 days. The volcano was primed for the 48th episode of high fountaining on July 18, 1986, when the conduit beneath Pu‘u ‘Ō‘ō ruptured again and magma erupted through new fissures at the base of the cone on both its uprift and downrift sides. These fissures were active for only 21 hours, but a third fissure, which opened 3 km downrift from Pu‘u ‘Ō‘ō on July 20, persisted and evolved into a single vent, later named Kupaianaha. Kupaianaha erupted almost continuously for the next 5.5 years (the main part of episode 48). The onset of episode 48 marked the end of episodic high fountaining and the transition to nearly continuous effusion. A lava lake developed over the Kupaianaha vent, and overflows from the lake built a broad, low shield that reached a relatively stable height of 45 m by November 1986. After weeks of continuous eruption, the main lava channel leading from the lake gradually roofed over, forming a lava tube. By November 1986, the tube had extended from the lake to the ocean, 12 km southeast, closing the coastal highway. Tube-fed flows overran 28 houses in the coastal communities of Kapa‘ahu and Kalapana over the next month.

Hawai'i↗
USGS2018

Groundwater-level, groundwater-temperature, and barometric-pressure data, July 2017 to February 2018, Hālawa Area, Oʻahu, Hawaiʻi

The Red Hill Bulk Fuel Storage Facility, operated by the U.S. Navy and located in the Hālawa area, Oʻahu, Hawaiʻi, includes 20 underground storage tanks that can hold a total of 250 million gallons of fuel. In January 2014, the U.S. Navy notified the Hawaiʻi Department of Health and U.S. Environmental Protection Agency of release of an estimated 27,000 gallons of fuel from the Red Hill Bulk Fuel Storage Facility. In response to past and potential future fuel releases, data are needed to evaluate groundwater flow in the surrounding area. During July 2017–February 2018, the U.S. Geological Survey collected groundwater-level data at 24 sites near the Red Hill Bulk Fuel Storage Facility. At 14 of the 24 sites, groundwater-temperature data were also collected, and at 6 of the 24 sites, barometric-pressure data were collected. During the data-collection period, a regional aquifer test was conducted in coordination with the operators of three production wells in the area. The recorded water-level changes in response to planned withdrawal changes during December 2017–February 2018 can be used to improve understanding of the groundwater-flow system. The scope of this report is limited to a non-interpretive presentation of the data and a brief discussion of the factors affecting the water-level data.

Hawai'i↗
USGS2018

Potential impacts of projected climate change on vegetation-management strategies in Hawai‘i Volcanoes National Park

Climate change is expected to alter the seasonal and annual patterns of rainfall and temperature in the Hawaiian Islands. Land managers and other responsible agencies will need to know how plant-species habitats will change over the next century in order to manage these resources effectively. This issue is a major concern for resource managers at Hawai‘i Volcanoes National Park (HAVO), where currently managed Special Ecological Areas (SEAs) for important plant species and communities may no longer provide suitable habitats in the future as the climate changes. Expanding invasive-species distributions also may pose a threat to areas where native plants currently predominate. The objective of this project was to combine recent climate-modeling efforts for the state of Hawai‘i with existing models of plant-species distribution in order to forecast suitable habitat ranges under future climate conditions derived from the Coupled Model Intercomparison Project, phase 3 (CMIP3) global circulation model that was dynamically downscaled for the Hawaiian Islands by using the Hawai‘i Regional Climate Model (HRCM). The HRCM uses the A1B emission scenario (a median future climate projection) from the Special Report on Emissions Scenarios (SRES). On the basis of this model, maps showing projected plant-species ranges were generated for four years as snapshots in time (2000, 2040, 2070, 2090) and for three different trajectories of climate change (gradual, linear, rapid) between the present and future. We mapped probabilistic surfaces of suitable habitat for 39 plant species (both native and alien [nonnative]) identified as being of interest to HAVO resource managers. We displayed these surfaces in terms of change relative to present conditions, whether the range of a given plant species was expected to contract, expand, or remain the same in the future. Within HAVO, approximately two-thirds (18 of 29) of the modeled native plant species were projected to contract in range, whereas one-third (11 of 29) were projected to increase. Most of the HAVO SEAs were projected to lose most of the native plant species modeled. Within HAVO, all alien plant species except Lantana camara were projected to contract in range within the park; this trend was observed in most SEAs, including those at low, middle, and high elevations. Congruence was good in the “current” (2000) distribution of plant-species richness and SEA configurations; however, the congruence between species-richness hotspots and SEAs diminished by the projected “end-of-century” (2090) distribution. Over time, the projected species-richness hotspots increasingly occurred outside of the currently configured SEA boundaries.

Hawai'i↗
USGS2018

Lava lake activity at the summit of Kīlauea Volcano in 2016

The ongoing summit eruption at Kīlauea Volcano, Hawai‘i, began in March 2008 with the formation of the Overlook crater, within Halema‘uma‘u Crater. As of late 2016, the Overlook crater contained a large, persistently active lava lake (250 × 190 meters). The accessibility of the lake allows frequent direct observations, and a robust geophysical monitoring network closely tracks subtle changes at the summit. These conditions present one of the best opportunities worldwide for understanding persistent lava lake behavior and the geophysical signals associated with open-vent basaltic eruptions. In this report, we provide a descriptive and visual summary of lava lake activity during 2016, a year consisting of continuous lava lake activity. The lake surface was composed of large black crustal plates separated by narrow incandescent spreading zones. The dominant motion of the surface was normally from north to south, but spattering produced transient disruptions to this steady motion. Spattering in the lake was common, consisting of one or more sites on the lake margin. The Overlook crater was continuously modified by the deposition of spatter (often as a thin veneer) on the crater walls, with frequent collapses of this adhered lava into the lake. Larger collapses, involving lithic material from the crater walls, triggered several small explosive events that deposited bombs and lapilli around the Halema‘uma‘u Crater rim, but these did not threaten public areas. The lava lake level varied over several tens of meters, controlled primarily by changes in summit magma reservoir pressure (in part driven by magma supply rates) and secondarily by fluctuations in spattering and gas release from the lake (commonly involving gas pistoning). The lake emitted a persistent gas plume, normally averaging 1,000–8,000 metric tons per day (t/d) of sulfur dioxide (SO 2 ), as well as a constant fallout of small juvenile and lithic particles, including Pele’s hair and tears. The gas emissions created volcanic air pollution (vog) that affected large areas of the Island of Hawai‘i. The summit eruption has been a major attraction for visitors in Hawai‘i Volcanoes National Park. During 2016, the rising lake levels allowed the lake and its spattering to be more consistently visible from public viewing areas, enhancing the visitor experience. The U.S. Geological Survey’s Hawaiian Volcano Observatory (HVO) closely monitors the summit eruption and keeps emergency managers and the public informed of activity.

Hawai'i↗
USGS2018

Volcano art at Hawai`i Volcanoes National Park—A science perspective

Long before landscape photography became common, artists sketched and painted scenes of faraway places for the masses. Throughout the 19th century, scientific expeditions to Hawaiʻi routinely employed artists to depict images for the people back home who had funded the exploration and for those with an interest in the newly discovered lands. In Hawaiʻi, artists portrayed the broad variety of people, plant and animal life, and landscapes, but a feature of singular interest was the volcanoes. Painters of early Hawaiian volcano landscapes created art that formed a cohesive body of work known as the “Volcano School” (Forbes, 1992). Jules Tavernier, Charles Furneaux, and D. Howard Hitchcock were probably the best known artists of this school, and their paintings can be found in galleries around the world. Their dramatic paintings were recognized as fine art but were also strong advertisements for tourists to visit Hawaiʻi. Many of these masterpieces are preserved in the Museum and Archive Collection of Hawaiʻi Volcanoes National Park, and in this report we have taken the opportunity to match the artwork with the approximate date and volcanological context of the scene.

Hawai'i↗
USGS2018

Population estimates of the Endangered Hawaiʻi ʻĀkepa (Loxops coccineus) in different habitats on windward Mauna Loa

Endangered Hawai‘i ʻĀkepas ( Loxops coccineus ) are endemic to Hawai‘i island, where they occur in five spatially distinct populations. Data concerning the status and population trends of these unique Hawaiian honeycreepers are crucial for assessing the effectiveness of recovery and management actions. In 2016, we used point‐transect distance sampling to estimate the abundance of Hawai‘i ʻĀkepas in portions of Hawai‘i Volcanoes National Park (HAVO) and the Kaʻū Forest Reserve (KFR) on Mauna Loa volcano. We then compiled the survey data from four other populations to provide a global population estimate. In our HAVO and KFR study area, we mapped habitat classes to determine the population densities in each habitat. Densities were highest (1.03 birds/ha) in open‐canopy montane ʻōhiʻa ( Metrosideros polymorpha ) woodland. In contrast, densities of the largest ʻĀkepa population on Mauna Kea volcano were highest in closed‐canopy ʻōhiʻa and koa ( Acacia koa ) forest where the species is dependent on nest cavities in tall (> 15 m), large (> 50‐cm diameter at breast height) trees. We surveyed potential nesting habitat in HAVO and KFR and found only one cavity in the short‐stature montane ʻōhiʻa woodland and five cavities in the tall‐stature forest. Differences in densities between the Mauna Kea and Mauna Loa populations suggest that Hawai‘i ʻĀkepas may exhibit different foraging and nesting behaviors in the two habitats. The estimated overall population density in the HAVO and KFR study area was 0.52 birds/ha, which equates to 3663 (95% CI 1725–6961) birds in their 11,377‐ha population range. We calculated a global population of 16,428 (95% CI 10,065–25,198) birds, which is similar to an estimate of 13,892 (95% CI 10,315–17,469) birds made in 1986. Our results suggest that populations are stable to increasing in the two largest populations, but the three other populations are smaller (range = 77–1443 birds) and trends for those populations are unknown.

Hawai'i↗
USGS2018

Continuous gravity and tilt reveal anomalous pressure and density changes associated with gas pistoning within the summit lava lake of Kīlauea Volcano, Hawaiʻi

Gas piston events within the summit eruptive vent of Kīlauea Volcano, Hawai‘i, are characterized by increases in lava level and by decreases in seismic energy release, spattering, and degassing. During 2010–2011, gas piston events were especially well manifested, with lava level rises of tens of meters over the course of several hours, followed by a sudden drop to preevent levels. The changes in lava level were accompanied by directly proportional changes in gravity, but ground deformation determined from tilt was anticorrelative. The small magnitude of the gravity changes, compared to the large changes in volume within the vent during gas pistons, suggests that pistoning involves the accumulation of a very low‐density (100–200 kg/m 3 ) foam at the top of the lava column. Co‐event ground tilt indicates that rise in lava level is paradoxically associated with deflation (the opposite is usually true), which can be modeled as an increase in the gas content of the magma column between the source reservoir and the surface. Gas pistoning behavior is therefore associated with not only accumulation of a shallow magmatic foam but also more bubbles within the feeder conduit, probably due to the overall decrease in gas emissions from the lava lake during piston events.

Hawai'i↗
USGS2018

Strong variation in weathering of layered rock maintains hillslope‐scale strength under high precipitation

The evolution of volcanic landscapes and their landslide potential are both dependent upon the weathering of layered volcanic rock sequences. We characterize critical zone structure using shallow seismic V p and V s profiles and vertical exposures of rock across a basaltic climosequence on Kohala peninsula, Hawai’i, and exploit the dramatic gradient in mean annual precipitation (MAP) across the peninsula as a proxy for weathering intensity. Seismic velocity increases rapidly with depth and the velocity–depth gradient is uniform across three sites with 500–600 mm/yr MAP, where the transition to unaltered bedrock occurs at a depth of 4 to 10 m. In contrast, velocity increases with depth less rapidly at wetter sites, but this gradient remains constant across increasing MAP from 1000 to 3000 mm/yr and the transition to unaltered bedrock is near the maximum depth of investigation (15–25 m). In detail, the profiles of seismic velocity and of weathering at wet sites are nowhere monotonic functions of depth. The uniform average velocity gradient and the greater depths of low velocities may be explained by the averaging of velocities over intercalated highly weathered sites with less weathered layers at sites where MAP > 1000 mm/yr. Hence, the main effect of climate is not the progressive deepening of a near‐surface altered layer, but rather the rapid weathering of high permeability zones within rock subjected to precipitation greater than ~1000 mm/yr. Although weathering suggests mechanical weakening, the nearly horizontal orientation of alternating weathered and unweathered horizons with respect to topography also plays a role in the slope stability of these heterogeneous rock masses. We speculate that where steep, rapidly evolving hillslopes exist, the sub‐horizontal orientation of weak/strong horizons allows such sites to remain nearly as strong as their less weathered counterparts at drier sites, as is exemplified by the 50°–60° slopes maintained in the amphitheater canyons on the northwest flank of the island.

Hawai'i↗
USGS2018

Integrating continuous stocks and flows into state-and-transition simulation models of landscape change

State-and-transition simulation models (STSMs) provide a general framework for forecasting landscape dynamics, including projections of both vegetation and land-use/land-cover (LULC) change. The STSM method divides a landscape into spatially-referenced cells and then simulates the state of each cell forward in time, as a discrete-time stochastic process using a Monte Carlo approach, in response to any number of possible transitions. A current limitation of the STSM method, however, is that all of the state variables must be discrete. Here we present a new approach for extending a STSM, in order to account for continuous state variables, called a state-and-transition simulation model with stocks and flows (STSM-SF). The STSM-SF method allows for any number of continuous stocks to be defined for every spatial cell in the STSM, along with a suite of continuous flows specifying the rates at which stock levels change over time. The change in the level of each stock is then simulated forward in time, for each spatial cell, as a discrete-time stochastic process. The method differs from the traditional systems dynamics approach to stock-flow modelling in that the stocks and flows can be spatially-explicit, and the flows can be expressed as a function of the STSM states and transitions. We demonstrate the STSM-SF method by integrating a spatially-explicit carbon (C) budget model with a STSM of LULC change for the state of Hawai'i, USA. In this example, continuous stocks are pools of terrestrial C, while the flows are the possible fluxes of C between these pools. Importantly, several of these C fluxes are triggered by corresponding LULC transitions in the STSM. Model outputs include changes in the spatial and temporal distribution of C pools and fluxes across the landscape in response to projected future changes in LULC over the next 50 years. The new STSM-SF method allows both discrete and continuous state variables to be integrated into a STSM, including interactions between them. With the addition of stocks and flows, STSMs provide a conceptually simple yet powerful approach for characterizing uncertainties in projections of a wide range of questions regarding landscape change.

Hawai'i↗
USGS2018

Pedestrian evacuation modeling to reduce vehicle use for distant tsunami evacuations in Hawaiʻi

Tsunami waves that arrive hours after generation elsewhere pose logistical challenges to emergency managers due to the perceived abundance of time and inclination of evacuees to use vehicles. We use coastal communities on the island of Oʻahu (Hawaiʻi, USA) to demonstrate regional evacuation modeling that can identify where successful pedestrian-based evacuations are plausible and where vehicle use could be discouraged. The island of Oʻahu has two tsunami-evacuation zones (standard and extreme), which provides the opportunity to examine if recommended travel modes vary based on zone. Geospatial path distance models are applied to estimate population exposure a s a function of pedestrian travel time and speed out of evacuation zones. The use of the extreme zone triples the number of residents, employees, and facilities serving at-risk populations that would be encouraged to evacuate and slightly reduces the percentage of residents (98–76%) that could evacuate in less than 15 min at a plausible speed (with similar percentages for employees). Areas with lengthy evacuations are concentrated in the North Shore region for the standard zone but found all around the Oʻahu coastline for the extreme zone. The use of the extreme zone results in a 26% increase in the number of hotel visitors that would be encouraged to evacuate, and a 76% increase in the number of them that may require more than 15 min. Modeling can identify where pedestrian evacuations are plausible; however, there are logistical and behavioral issues that warrant attention before localized evacuation procedures may be realistic.

Hawai'i↗
USGS2018

Biology and impacts of Pacific Islands invasive species. 14. Sus scrofa the feral pig (Artiodactyla: Suidae)

Feral pigs ( Sus scrofa L.) are perhaps the most abundant, widespread, and economically significant large introduced vertebrate across the Pacific island region. Unlike many other nonnative invasive species, feral pigs have both cultural and recreational importance in the region, complicating their management. Today, Pacific island feral pigs are a mixture of several strains of domestic swine, Asiatic wild boar, and European wild boar. Due to their generalist diet and rooting behavior, feral pigs alter soils and watersheds and negatively impact native and nonnative flora and fauna. As a result, feral pigs have played a role in the extinction of several species of plants and animals on Pacific islands and have negative effects on both ecotourism and agricultural industries in the region. Despite numerous published studies on feral pigs in the Pacific island region, of which the majority include systematic analyses of original empirical data, some fundamental aspects of feral pig ecology remain poorly characterized, at least partly due to the remote and inaccessible environments that they often inhabit. To address these knowledge gaps, effort should be made to integrate research conducted outside the Pacific island region into local management strategies. This review summarizes the origins, history, ecology, environmental effects, and current management of feral pigs in the Pacific island region; integrates regional scientific findings with those of other insular and continental systems; and identifies current knowledge gaps requiring further research to inform the ecology and management of this impactful invasive species.

Hawai'i↗