Geology topics

Research about Hawaii

Source-linked reports with geographic coverage including Hawaii.

At least 55 records · Page 3Linked to original sources

USGS2026

Petrologic and geochemical characterization of the first year of the 2024–ongoing episodic Halemaumau eruption of Kilauea (Episodes 1–39)

Kīlauea has been erupting episodically since December 23, 2024 (and is ongoing at the time of this writing in 2026) with two consistently active vents in Halema‘uma‘u producing lava fountains ranging in height from 40 to 540 m. In the first year of the eruption (through December 24, 2025, episode 39), the U.S. Geological Survey's Hawaiian Volcano Observatory collected 178 samples for eruption monitoring purposes and used a subset of 80 for near-real-time geochemical analyses. Tephra, lava, and recycled lava lake ooze-out samples have been studied on inter-episode timescales using diverse microanalytical techniques, where research-scale investigations have proven to be advantageous pseudo-near-real-time techniques. Here we present a geochemical and petrologic overview of episodes 1–39 to better understand eruption dynamics and identify changes at Kīlauea following the 2018 summit caldera collapse. There are no significant intra-episode geochemical changes that might be related to variable fountain heights or episode durations, suggesting that eruption dynamics are instead primarily controlled by viscosity and conduit geometry changes throughout a single episode and between episodes. There is variable but clear influence of the still-molten lava lake interior on compositions of this eruption, including in tephra samples from lava fountains, indicating that the vent conduits are connected in some way at depth with the still molten passive lava lake core. Tephra glasses (7.0–7.8 wt.% MgO) show cyclic changes in MgO that were decoupled from lava fountain heights and behavior in episodes 1–28 but positively correlated after episode 29. Additionally, whole-rock and glass compositions are enriched in minor elements such as K 2 O and TiO 2 compared to 2008–2023 summit eruptions, tracking the arrival of a new magma composition that may be related to the prolonged episodic eruptive behavior. Olivine-hosted melt inclusions from five episodes have ~0.35–0.43 wt.% H2O, < 300 ppm CO 2 and < 1500 ppm S, with no significant variations between episodes. Melt and fluid inclusion barometry show that magmas driving these episodes are stored and sourced from the shallow 1–2 km Halemaʻumaʻu reservoir, as were olivine from the 2023 summit eruption. The ongoing episodic eruption also has higher bulk-rock MgO compared to the five previous summit eruptions (2020−2023) and the forsterite (Fo) content of olivine has varied systematically from 2015 to 2025 with the equilibrium olivine composition of the Halema‘uma‘u reservoir increasing from Fo 80.7 in 2015 to Fo 82.7 by 2025. We argue that the Halemaʻumaʻu reservoir is heating up because the rate of magma supply is outpacing effusion and cooling following caldera collapse in 2018.

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USGS2026

Insights from more than a year of ongoing episodic lava fountaining at Kilauea

Episodic lava fountaining is rare globally, with only three occurrences from Kīlauea (Hawaii) since 1823. Beginning in December 2024, an eruption within the summit crater, Halemaʻumaʻu, has produced 52 fountaining episodes to date, each lasting typically for hours and separated by days to weeks. Although multiple mechanisms have been proposed, fundamental questions remain about how magma reservoir pressure, conduit permeability, and volatile exsolution control fountaining onset. We present a multi-parameter record of episodic fountaining at Kīlauea using modern geochemical, geophysical, and geologic monitoring. These observations revealed systematic correlations between fountaining and summit inflation, enabling unprecedented quantitative forecasts. This eruption will provide new constraints on the timing, evolution, and processes driving episodic fountaining globally, and highlights Kīlauea’s role as a natural laboratory for studying volcanic processes.

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USGS2025

Utilizing crystal records to determine the underlying architecture and timescales of magmatic processes during the 2022 Mauna Loa eruption

Details of Mauna Loa’s plumbing system and magma storage dynamics are relatively poorly constrained, relative to nearby Kīlauea volcano. Recent studies have begun to address this gap in knowledge using geophysical imaging or olivine-focused petrology. Here, we use the crystal cargo from the 2022 summit and Northeast Rift Zone eruption to advance our understanding of Mauna Loa’s storage regions and pre˗eruptive processes. We identify textural and geochemical populations of olivine, orthopyroxene, clinopyroxene, and plagioclase macrocrysts as well as evolved glomerocrysts consisting of orthopyroxene, clinopyroxene, and plagioclase. Summit versus rift zone trends can be distinguished between specific crystal populations and are used to infer magma transfer pathways. Melt inclusion barometry from three orthopyroxene populations indicate crystallization depths of ~2–3 km which coincide with previous olivine˗hosted fluid inclusion barometry across Mauna Loa’s recent 200˗yr eruptive history. We combine orthopyroxene˗hosted melt inclusion barometry with diffusion chronometry on the same crystals using Fe˗Mg interdiffusion to estimate timescales of mixing and recharge prior to the eruption. Summit orthopyroxene yield timescales of weeks to months, aligning with geophysically recognized pre˗eruptive intrusion events and previously determined olivine timescales. Northeast Rift Zone orthopyroxene crystals have resorbed cores and yield short pre˗eruptive mixing timescales on the order of hours to days. Chemistry and timescales from the orthopyroxene populations suggest some of the 2022 magmas may have bypassed the shallowest portions of the summit reservoir system and were transferred directly into the rift zone syn˗eruptively.

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USGS2025

Near-real-time geochemical monitoring of Hawaiian volcanoes using energy dispersive X-ray fluorescence (EDXRF)

Syn-eruption geochemical monitoring during volcanic activity is an important component of integrated volcanic monitoring. Volcanoes on the Island of Hawai‘i are primarily monitored by the U.S. Geological Survey’s Hawaiian Volcano Observatory using instrumental networks, field surveys, satellite observations, and petrologic monitoring. In collaboration with the University of Hawaiʻi at Hilo, an important component of this monitoring is near-real-time (generally within 24 h of sample collection) bulk-rock geochemistry using benchtop energy-dispersive X-ray fluorescence (EDXRF). Bulk-rock geochemistry, coupled with additional petrologic and geophysical analyses, are used to track eruption dynamics to help facilitate identification and understanding of changes that signal the onset of potentially hazardous activity. In this paper, we present EDXRF methodology for bulk-rock analysis used to evaluate the 2018 Kīlauea and 2022 Mauna Loa eruptions and compare this technique to other geochemical methods. Syn-eruption geochemical monitoring using EDXRF provides reliable quantitative data that is important for understanding eruption dynamics. Critical to this process are calibrating the instrument for analysis over the same range of compositions expected during volcanic activity, compiling a relevant database from past eruptions on the same instrument for comparison, and having the physical infrastructure and trained personnel to complete the analyses in a timely fashion. In addition to the scientific goals of petrologic monitoring, near-real-time geochemical analysis in Hawaii provides important information about the nature of on-going eruptions and informs decision-makers and the public about associated evolving hazards.

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USGS2025

Getting ahead of the crises: Developing an avian malaria disease management plan for Hawaiian forest birds

Avian malaria is an existential threat to a majority of native Hawaiian forest birds. Climate change is facilitating the spread of malaria to historically disease-free areas, and despite the risk of native Hawaiian forest bird extinctions from malaria outbreaks, no comprehensive disease management plans exist for forest bird conservation areas. Hakalau Forest National Wildlife Refuge, Hawai‘i, supports a thriving bird community in a historically disease-free area that is now vulnerable to malaria incursion. Drawing on the expertise of land managers and research scientists, we developed an approach that could be used to proactively address the risk of expanding malaria into the Refuge. The plan lays out a multi-level approach that includes options for monitoring and management actions depending on defined threat levels: Vigilant, High Alert, Disease Outbreak, and Crisis levels. Initial Vigilant and High Alert levels monitor bird populations, climate conditions, and mosquito occurrence for signs of possible disease outbreaks, with higher levels shifting toward more direct management responses. While specific actions will change as new tools become available, the proactive approach can help Refuge managers better respond to changing malaria levels in the future and provide a model for managing disease here in Hawai‘i and elsewhere.

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USGS2025

Growth of a passive lava lake during the 2020–2021 eruption of Kīlauea volcano, Hawaii

We investigate the growth of a passive lava lake in Halemaʻumaʻu crater during the December 2020 to May 2021 eruption of Kīlauea volcano, Hawaii. Fed by vents above their surfaces, the formation of passive lava lakes in topographic lows is an important process in the growth of basaltic volcanoes. We captured visible and thermal images during 17 helicopter overflights and applied structure-from-motion photogrammetry to create digital elevation models and orthomosaics of Halemaʻumaʻu. These data products allowed us to track eruptive activity and processes. The bulk time-averaged discharge rate (TADR) in December 2020 initially exceeded 100 m 3 s –1 but decreased to < 10 m 3 s –1 within seven days. By February 2021, TADR was < 2 m 3 s –1 and continued to decrease until the eruption ended in May 2021. A total volume of 40.6 ± 0.5 × 10 6 m 3 of lava filled Halemaʻumaʻu to a depth of 225 m. As TADR decreased, the lake progressively developed an immobile, solidified crust, beginning with surfaces farthest from the vent. This immobile surface rose endogenously, whereas exogenous surface rise occurred near the vent. Eruptive activity at a vent ended when the level of the lake surface exceeded that of the vent, which we attribute to the effects of lava sitting above the vent on ascending magma. Regular helicopter overflights, combined with field observations and the extensive monitoring network at Kīlauea, generated an unprecedented density of observations that provide insights into the emplacement of passive lava lakes and how these eruptions wane and end.

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USGS2025

The continued decline of the Palila (Loxioides bailleui) on Mauna Kea, Island of Hawaiʻi

Palila ( Loxioides bailleui ) are critically endangered Hawaiian honeycreepers specializing on māmane ( Sophora chrysophylla ) seeds and restricted to Mauna Kea volcano on the Island of Hawaiʻi. Recently, the population was estimated to decline by 89% between 1998 and 2021, despite decades of ungulate removal, fence construction, māmane regeneration, fire suppression, and predator control. To inform managers with the most recent update on the status and trends of the Palila population, we analyzed annual bird survey data collected using point-transect distance sampling since 1998, including new annual survey data from 2022, 2023, and 2024. Prior to analysis, we predicted the population trajectory would change between 2021 and 2024 because of continued management actions promoting habitat recovery. We used distance sampling, log-linear regression, and state-space modeling to produce the new estimates and analyze trends across the time series. The 2022 population estimate was 367 to 742 birds (95% confidence interval; point estimate: 545), the lowest in recorded history. The 2023 and 2024 estimates of 374 to 842 birds (point estimate: 596) and 412 to 970 birds (point estimate: 666) were the second and third lowest in our time series, respectively. Our estimates for years before 2022 show population fluctuations between 4000 to 6800 birds from 1998 to 2005, then a steep decline through 2010. For the next decade, abundance fluctuated around 1000 birds, before declining again in 2021 to less than 700 birds. From 1998 to 2024, the population declined by more than 90%, or 205 birds per year, with 100% statistical support for an overall downward trend, despite significant management efforts and research. The greatest threats facing the Palila, if familiar, are not being eliminated swiftly enough to promote their recovery. The currently small and range-limited population is vulnerable to future climate-related events such as drought and fire. Continued monitoring can help to assess the response of Palila to adaptive management actions and changing environmental conditions.

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USGS2025

The Hawaiian Volcanoes Supersite: Open data for the benefit of science and society

The Hawaiian Volcanoes Supersite was established in 2008 with the goal of making large amounts of volcano monitoring data, especially satellite measurements, freely available at a site of international interest, scientific importance, and impactful natural hazards. The location was chosen because of the long history of volcanological research and innovation on the Island of Hawaiʻi, as well as the need for monitoring, assessing, and mitigating volcanic hazards for the local population. Ground-based data are provided by the U.S. Geological Survey Hawaiian Volcano Observatory, and several national space agencies have contributed thousands of satellite synthetic aperture radar and other data that would have otherwise required special grants or commercial purchase. Since the Hawaiian Volcanoes Supersite was initiated, the vast quantity of open space-based data has resulted in the development of new applications and methodologies, successful responses to volcanic crises, and research that has informed monitoring and hazards mitigation activities. While there remain opportunities for additional coordination among supersite users and for synergistic studies that make use of the full spectrum of available ground- and space-based data, the Hawaiian Volcanoes Supersite has achieved its goals of stimulating basic research to better understand Hawaiian volcanism and aiding in responses to hazardous geologic processes. The effort serves as a model for the benefits of open, low-latency, and comprehensive satellite data applied to disaster risk management and reduction, meeting a vision that has been laid out repeatedly in international agreements and accords.

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USGS2025

Nodal seismic deployment on Mauna Loa volcano, Hawaii: Dataset and preliminary insights

Mauna Loa is the largest active volcano on Earth, comprising ∼51% of the Island of Hawai‘i’s landmass and posing significant risks to the island’s communities, infrastructure, and natural environment. Historical eruptions have produced lava flows that have reached the ocean in as little as 3 hr. The timing and location of such lava flows in the past 200 yr underscore how critical determination of the location and geometry of magma storage and structure is for volcanic hazard assessment and eruption forecasting. Now, after nearly 38 yr of volcanic quiescence, Mauna Loa has erupted again. On 27 November 2022, fissures initiated within the summit caldera and then migrated to the northeast rift zone, where they generated a large lava flow that threatened a major highway. To improve our understanding of the geometry of this magma system, we deployed a temporary nodal array on Mauna Loa in the summer of 2024. This increased our seismic coverage sufficiently to image this magmatic system. This nodal array consists of 33 seismometers distributed on and around the volcano and was deployed for over three months to record seismic signals. The primary objective of this project is to resolve the high‐resolution seismic velocity structure and characterize seismic features associated with magma storage and ascent pathways. In this article, we present an overview of the deployment, evaluate the quality of the data, and show example recordings to evaluate the suitability of the data set for future seismic investigations, including earthquake relocation, seismic tomography, and receiver function analysis. Comparisons with nearby permanent broadband and short‐period seismic stations demonstrate that the nodal array recorded high‐quality waveforms, making it a valuable resource for constraining the magmatic system beneath Mauna Loa at multiple scales.

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USGS2025

Impact of warming and suspended terrigenous sediment on the Hawaiian reef coral Montipora capitata

Coral reefs near high human population areas suffer from sedimentation and increased turbidity due to coastal development. However, there is limited research on how key species respond to turbidity caused by terrigenous sediment and how this response may change with increased water temperatures. This study investigated the effects of ambient and elevated turbidity (+ 26 NTU) in combination with ambient (27.1 °C) and elevated temperature (+ 4.1 °C; 31.2 °C) on the dominant Hawaiian reef coral Montipora capitata , collected from two Kāneʻohe Bay watersheds with distinct environmental histories. Using intermittent flow respirometry, we found that acute (12 h) exposure to elevated turbidity and temperature impacted algal symbionts ( Symbiodinium spp. ) but not the coral host, suggesting a potential delayed host physiological response. Corals from south Kāneʻohe Bay, where restricted water circulation and urbanization have degraded water quality, were more sensitive to stressors than those from the less-impacted northern sites, indicating that physiological responses vary by location and may be influenced by watershed conditions. The findings suggest that while short-term turbidity and warming impact Symbiodinium spp. immediately, prolonged exposure may lead to cascading effects on the coral host. Understanding these species-specific and location-dependent responses enhances our ability to guide restoration and conservation efforts for coral ecosystems facing both local (turbidity) and global (warming) stressors.

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USGS2025

Submarine groundwater discharge creates cold‐water refugia that can mitigate exposure of heat stress in nearshore corals

Coral reef mortality around the world is accelerating due to human activities and rising sea temperatures that cause bleaching, which is expected to become more frequent. Our ability to predict which corals will be most resilient, however, remains limited due to insufficient information characterizing nearshore temperature and habitat conditions. In this study, we examine how submarine groundwater discharge (SGD) reduces nearshore water temperatures and exposure of corals to heat stress, complementing the understanding that SGD can adversely affect coral when it contains elevated nutrient concentrations. Data from fixed nearshore sensors and vertical depth profiles along ~100 km of the western shoreline of the Island of Hawai’i from 2003 to 2014 demonstrate that submarine groundwater discharge (SGD) can reduce nearshore water temperatures by 1 °C–5°C and create estuarine-like conditions with salinities as low as 20 PSU, where the prevalent coral species, Pocillopora meandrina, Porites lobata , and Montipora capitata , thrive. Time-series temperature records reveal that exposure to high ambient ocean temperatures, which are known to initiate bleaching events, are reduced up to 5%–46% of the time. Coral health surveys indicated coral bleaching in response to moderately high annual temperatures in 2010 and 2011, with more colonies affected farther from cold, SGD-fed waters. Synthesis of these results, along with coral response data following the more extreme marine heat wave of 2014–2015, demonstrates lower coral loss and greater coral recovery near groundwater seeps, particularly those with higher flux and influence on reducing nearshore water temperatures. Our results demonstrate that SGD may therefore provide a beneficial ecosystem service and enhance coral reef resilience, particularly where human-related nutrient additions to groundwater can be mitigated. The implications of our findings are relevant across tropical coasts where groundwater inputs can be substantial, such as the Caribbean and Indo-Pacific, and contribute to improving our understanding of coral sensitivity to gradients in temperature and nutrient stress. Improved management of groundwater resources could thus be vital to local–regional strategies for mitigating future heat stress.

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USGS2025

Fluid inclusion constraints on the geometry of the magmatic plumbing system beneath Mauna Loa – Part I: Lavas and tephras

There are few petrological constraints on magma storage depths at Mauna Loa, Hawai‘i. Yet understanding the geometry of the magmatic plumbing system is critical for interpreting geophysical signals of unrest at this very high-threat volcano. We address this gap by examining CO₂-rich fluid inclusions (FI) in lava and tephra from seven eruptions (8870 ± 56 14C yr BP, 1852, 1855, 1868, 1949, 1950, and 1984), supplemented with published data from 2022. Raman spectroscopy was used to determine FI densities, from which entrapment pressures were calculated using a CO₂-H₂O equation of state. Most FI record pressures of ~ 0.25–1.25 kbar (~ 2–5 km depth below the summit), consistent with geophysical estimates from the past 40 years. In summit eruptions, FI hosted in more evolved olivine and orthopyroxene clots (Fo and Mg# < 84) record slightly shallower pressures than those in more primitive olivines (Fo > 84) from rift zone eruptions, suggesting a crystal-poor evolved cap near the top of the reservoir (~ 2 km). The similarity in storage depths across all eight eruptions indicates that Mauna Loa’s magmas have tapped a quasi-stable reservoir over the past two centuries, and possibly over 10 kyr. Electron backscatter diffraction reveals deformations to the crystal lattice in Fo82-83 olivines, likely due to deformation during storage in mush piles. The intensity of deformation is comparable to that seen at Kīlauea, implying that mush pile stress may be decoupled from edifice size or longevity. Finally, SO₂ contents in FI increase from ~ 2 mol% at 2 kbar to ~ 15 mol% at 0.5 kbar, suggesting sulphur degassing begins far deeper than the 0.2–0.3 kbar commonly assumed for Hawaiian systems. This validates the newest generation of S degassing models (e.g., Sulfur_X), and explains precursory SO2 emissions in the ~3 hours prior to the onset of the 2022 eruption (Esse et al. 2025).

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USGS2025

Quantifying landscape-level biodiversity change in an island ecosystem: A 50-year assessment of shifts in the Hawaiian avian community

Hawaii has experienced profound declines in native avifauna alongside the introduction of numerous bird species. While site-specific population studies are common, landscape-level analyses of avian population dynamics are rare, particularly in island ecosystems. To address this gap, we used a density surface model to create a spatio-temporal projection of population densities and distributions across the Island of Hawai‘i, spanning nearly five decades (1976–2023). We incorporated environmental covariates of habitat, precipitation, and elevation, to further refine our projections. Our analysis encompassed nine native and six non-native bird species, inhabiting a range of ecological niches. We found five out of nine native species have declined in density and range size while four were stable. For non-native species, two were stable, one was decreasing, and three were increasing in density and range size. Our landscape projections can inform management by suggesting areas critical for habitat preservation and land acquisition for conservation, identifying where range fragmentation is occurring, and pinpointing locations of multi-species declines that are likely driven by a common cause. Our study demonstrates how long-term, landscape-level monitoring and analyses can advance understanding and addressing biodiversity loss, particularly in vulnerable tropical island ecosystems.

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USGS2025

Host preferences of non-native Acalolepta aesthetica (Coleoptera: Cerambycidae) on the Island of Hawai'i

1. Understanding the host preferences of non-native polyphagous insects is a key step in anticipating their impacts. 2. We apply a technique from wildlife ecology, a resource selection function, to quantify the host preferences of Acalolepta aesthetica Olliff (Coleoptera: Cerambycidae: Lamiinae) in its non-native range on the Island of Hawaiʻi. We then visually surveyed its preferred host to map its distributional extent and conducted laboratory no-choice tests to assess risks to common native woody species. 3. The preferred host of A. aesthetica was the state tree, Aleurites moluccanus (L.) Willd., the kukui (or candlenut). Cacao ( Theobroma cacao L.) was the second most preferred host. Infestations were also observed in Citrus species, Artocarpus altilis (Parkinson) Fosberg (ʻulu or breadfruit) and Persea americana Mill. (avocado), but preferences among these taxa were statistically indistinguishable. 4. Acalolepta aesthetica females oviposited on all tested species in no-choice trials, but larvae growing within ʻōhiʻa ( Metrosideros polymorpha Gaudich.) and koa ( Acacia koa A. Gray) died. It therefore poses a low risk to these two tree species, which are foundational to Hawaiian native forests. Acalolepta aesthetica was able to complete its development within ʻōlapa ( Cheirodendron trigynum (Gaudich.) A. Heller), which could be monitored if the distribution of A. aesthetica spreads to native forests. 5. The host species preferred by A. aesthetica are highly valued for agricultural, horticultural and cultural uses. Developing monitoring and management techniques for this cerambycid and employing strong biosecurity could prevent human-mediated spread and limit negative impacts to other Hawaiian Islands, the U.S. mainland, and the world.

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USGS2025

Fluid inclusion constraints on the geometry of the magmatic plumbing system beneath Mauna Loa – Part 2: Xenoliths

Mauna Loa volcano erupts crystal-poor material at its summit and more crystal-rich material on its rift zones. Some of the more olivine-rich lava flows contain xenoliths with diverse mineralogy, including cumulate harzburgites with high-Mg# orthopyroxenes and high-Fo olivines (both > 84). Previous experimental work and thermodynamic modelling has proposed that high-Mg# orthopyroxenes only crystallize from Mauna Loa melts at high pressures (> 6 kbar, > 20 km), leading to suggestions that there is a region of sub-Moho magma storage at Mauna Loa in addition to the geophysically imaged magma reservoir at 2–5 km depth below the summit. We use melt and fluid inclusion barometry combined with thermodynamic models to further investigate this suggestion. Fluid inclusion data from harzburgites and dunitic xenoliths yield storage depths remarkably similar to those found in non-xenolithic crystals from lavas and tephras, with a clear peak at ~ 2–3 km (below the summit). Depths from melt inclusions in these xenoliths overlap with fluid inclusion pressures, ruling out the possibility of fluid inclusion re-equilibration during a period of stalling in a shallower reservoir. We examine five different thermodynamic models and find that the minimum pressure of olivine-orthopyroxene co-saturation varies by ~ 4 kbar (~ 12 km). These models also fail to predict that orthopyroxene is stable in ~ 15–80% of compositionally relevant experimental charges which grew orthopyroxene. Overall, this shows that phase stability modelling is an unreliable method of determining magma storage depth at Mauna Loa. We suggest that model discrepancies reflect a lack of experimental constraints on orthopyroxene stability at > 1200 ℃ and 0.01–5 kbar. Based on the presence of large oikocrystic orthopyroxenes completely enclosing rounded olivine chadacrysts, we suggest that these harzburgitic xenoliths formed through the reaction of intruding melts with olivine mush piles within the Mauna Loa edifice at ~ 3 km depth below the summit, with no need for a deeper storage reservoir. The predominance of pre-eruptive shallow storage means that there is more chance of detecting reservoir destabilization with geophysical monitoring techniques compared to a scenario where melts are supplied from sub-Moho reservoirs.

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USGS2025

Variation in gene expression across infection status and elevation in a Hawaiian honeycreeper

Introduced pathogens exert novel selection on hosts, and although many host species have experienced drastic population declines in the absence of adaptation, some hosts have adapted to highly virulent pathogens. For instance, mosquitoes and Plasmodium relictum introduced to the Hawaiian Islands have resulted in extinctions and catastrophic population declines due to avian malaria, particularly in the diverse clade of Hawaiian honeycreepers. However, some species, such as the Hawai'i 'amakihi ( Chlorodrepanis virens ), can survive infection. Immunity exists in low-elevation populations where mosquitoes are abundant, whereas high-elevation, unexposed populations of 'amakihi display greatly reduced immunity. To explore the basis of adaptation to P. relictum in low-elevation 'amakihi, we sequenced transcriptomes from 24 low-elevation and 15 high-elevation 'amakihi. We tested for differential gene expression between (i) infected and uninfected birds and (ii) low- and high-elevation birds. Infected birds showed significant differences in expression across many transcripts with diverse cellular functions involved in different pathways of immune response; eight of the top 13 transcripts blasted to genes previously implicated in immunity to malaria in 'amakihi, and 11 have been identified in other infectious disease systems. Thirteen transcripts showed a trend of higher expression in high-elevation birds. These transcripts blasted to genes involved in metabolism, blood coagulation, and immune response. Our results provide increasing support for a subset of genes involved in immunity to malaria in 'amakihi and hint at possible antagonistic interactions between response to pathogens and environmental characteristics associated with elevation. Further work clarifying the nature of these interactions could benefit conservation efforts of Hawaiian honeycreepers in upper elevation refugia that are increasingly subject to malaria exposure.

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USGS2025

A decade of precursory seismicity at Mauna Loa: 2013–2022

The 2022 eruption of Mauna Loa was preceded by nearly 10 years of seismic unrest. Using the earthquake catalog of the Hawaiian Volcano Observatory, we describe and explore many aspects of unrest between January 1, 2013, and the start of the eruption on November 28, 2022 (UTC). Earthquakes associated with unrest occurred above an inflating dike at shallow depths under and to the south of Moku‘āweoweo and in the cluster of seismicity to the west of Moku‘āweoweo associated with a buried rift zone. Earthquakes also occurred in a broad region at the base of the crust, likely associated with a zone of magma accumulation. Unrest is broken down into four phases of increasing intensity with time and into individual geographic regions. While activity occurring at shallow depths under the caldera often alternated with activity on the west flank in the first two phases of unrest, the third phase of unrest featured increased rates of earthquake activity in both areas acting concurrently. We also document a slow shift in seismicity across multiple years from the south of Moku‘āweoweo to an area under the caldera that likely represents a change in the location of the intrusion through time. Broadly speaking, unrest observed in advance of the 2022 eruption occurred in the same areas as the unrest preceding eruptions in 1975 and 1984. Furthermore, precursory unrest prior to eruptions in 1975, 1984 and 2022 lasted years and culminated in an intense phase of seismic activity lasting on the order of hours that represented the final dike propagation to the surface. Concurrent earthquake activity under Moku‘āweoweo and the west flank of Mauna Loa, paired with a shift in earthquakes under Moku‘āweoweo were the two most notable long-term precursors to an eruption; however, neither provided an actionable timeline of an impending eruption. The decade of precursory seismicity prior to the 2022 eruption is similar to long precursory phases prior to eruptions in 1975 and 1984 and underscores the challenges of informing on eruption hazards in a timely manner. By combining seismic activity with other geophysical fields such as geodesy and gravity, we present a conceptual model to aid in the interpretation of future unrest at Mauna Loa.

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USGS2025

Gram staining reveals diverse bacterial associations in coral cell-associated microbial aggregates in the Pacific Ocean

Cell-associated microbial aggregates (CAMAs) (also referred to as coral-associated microbial aggregates) have been observed in 24 coral species from the Pacific Ocean, and studies indicate most contain gram-negative bacilli from the genus Endozoicomonas. Here, we used histology with Gram staining to evaluate the morphology and distribution of CAMAs in six species of scleractinian corals from Hawaii and Palmyra. Within CAMAs, we observed the coexistence of bacteria with differing morphologies and Gram-staining properties both within and among coral species. Pocillopora and Acropora had mostly gram-negative bacilli, whereas gram-negative cocci dominated in Porites . Acropora had the highest abundance of gram-positive CAMAs. The anatomical distribution of CAMAs varied by coral species. CAMAs dominated in the tentacles of Pocillopora meandrina , Pocillopora grandis , and Porites evermanni, were mostly in the coenenchyme of Acropora cytherea , and were found equally between tentacles and coenenchyme in Porites compressa and Porites lobata . Tissue-layer distribution also varied, with CAMAs mainly in the epidermis of Pocillopora but in the gastrodermis of Porites and Acropora . The diversity of bacteria in CAMAs and their anatomic distribution in Pacific corals may be more complex than previously understood. This indicates other bacterial species, in addition to Endozoicomonas, are colonizing CAMAs in corals from the Pacific Ocean.

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