Geology topics

David Lallemant

Publications and source records attributed to David Lallemant.

5 recordsLinked to original sources

USGS2025

Developing empirical fragility functions for lava flow building damage

Fragility functions are vital tools in volcanic risk assessments to evaluate the probability of damage to structures at given hazard intensities. Traditionally, lava flow damage is assumed to be binary , whereby in contact with lava results in complete destruction and not in contact with lava remains undamaged. However, past studies present examples of structures exhibiting resistance to lava and not destruction . Developing empirical fragility functions requires damage data . We collected data from field campaigns and aerial imagery to assess damage across three case studies: 2021 Cumbre Vieja lava flows, La Palma, 2018 lower East Rift Zone lava flows, Kīlauea, Hawaiʻi, and 2014–2015 Fogo lava flows, Cabo Verde. This involved manually digitising 4545 structure footprints and assigning types and damage state categories to 10,439 structures. Of the impacted structures, 6 % were classified as damaged (not destroyed). Using this dataset, we developed the first empirical fragility functions from multiple eruptions for assessing lava flow damage, for masonry, metal , and timber building types. The functions reflect the probability of a structure sustaining any of six levels of damage severity given final lava flow thickness. Lava flows thicker than 6 m generally destroy structures, but some structures, particularly masonry buildings or those with a circular shape, can resist flows thinner than 6 m. The fragility functions reflect that lava flow impacts are not binary, and that structure types and shape are important. These empirical fragility functions can differentiate between structural attributes, thereby enhancing damage, risk, and impact assessments for lava flows, for places with similar building types.

International Journal of Disaster Risk Reduction↗

USGS2024

Lava flow impacts on the built environment: Insights from a new global dataset

The recent destruction of thousands of homes by lava flows from La Palma volcano, Canary Islands, and Nyiragongo volcano, Democratic Republic of Congo, serves as a reminder of the devastating impact that lava flows can have on communities living in volcanically active regions. Damage to buildings and infrastructure can have widespread and long-lasting effects on rehabilitation and livelihoods. Our understanding of how lava flows interact with buildings is limited and based upon sparse empirical data. Often a binary impact is assumed (destroyed when in contact with the flow and intact when not in contact with the flow), although previous events have shown this to be an oversimplification. Empirical damage data collected after past events provide an evidence base from which to better understand lava flow impacts across a range of building types, environments, and eruption styles, as well as to explore the temporal and spatial trends in these impacts. However, information on lava flow impacts is scattered across literature, reports, and maps; no comprehensive dataset of lava flow impacts exists. In this study, we compile and standardise lava flow impact information from previously compiled data, eruption records, and published literature to create the first comprehensive global dataset of impacts on the built environment from lava flows. We found that since the first recorded event between 5494 yr B.P. and 5387 yr B.P., lava flows from at least 155 events have impacted buildings or infrastructure (e.g., roads, electricity pylons, ski-lifts), with most (47%, n = 73) recorded as located in Europe. Over the last century, there have been approximately seven lava flow impact events per decade ( n = 71 total). This greatly expands on the past compilations of lava flow impact events. Since ca. 1800 CE, impacts have been consistently documented for less than 14% of recorded eruptions with lava flows globally; prior to 1800 CE, impacts were recorded much more variably (between 0 and 70% of lava flows in any 10-year time bin). The most destructive recorded events were the 1669 CE lava flows at Etna volcano, Italy, which destroyed up to 12 villages and part of the city of Catania, and the 2002 CE lava flows at Nyiragongo volcano, Democratic Republic of Congo, which destroyed up to 14,000 buildings. We found that few studies in the dataset report building typology, damage severity, or hazard intensity at the building-level scale, limiting our ability to assess past building-lava interactions. Future collection of building-level hazard and impact data, supplemented with non-English language records, can be used to inform models that forecast future impacts, support lava flow risk assessments, and develop potential mitigation measures.

Journal of Applied Volcanology↗

USGS2022

Damage assessment for the 2018 lower East Rift Zone lava flows of Kīlauea volcano, Hawaiʻi

Cataloguing damage and its correlation with hazard intensity is one of the key components needed to robustly assess future risk and plan for mitigation as it provides important empirical data. Damage assessments following volcanic eruptions have been conducted for buildings and other structures following hazards such as tephra fall, pyroclastic density currents, and lahars. However, there are relatively limited quantitative descriptions of the damage caused by lava flows, despite the number of communities that have been devastated by lava flows in recent decades (e.g., Cumbre Vieja, La Palma, 2021; Nyiragongo, Democratic Republic of Congo, 2002 and 2021; Fogo, Cape Verde, 2014–2015). The 2018 lower East Rift Zone (LERZ) lava flows of Kīlauea volcano, Hawaiʻi, inundated 32.4 km 2 of land in the Puna District, including residential properties, infrastructure, and farmland. During and after the eruption, US Geological Survey scientists and collaborators took over 8000 aerial and ground photographs and videos of the eruption processes, deposits, and impacts. This reconnaissance created one of the largest available impact datasets documenting an effusive eruption and provided a unique opportunity to conduct a comprehensive damage assessment. Drawing on this georeferenced dataset, satellite imagery, and 2019 ground-based damage surveys, we assessed the pre-event typology and post-event condition of structures within and adjacent to the area inundated by lava flows during the 2018 LERZ eruption. We created a database of damage: each structure was assigned a newly developed damage state and data quality category value. We assessed 3165 structures within the Puna District and classified 1839 structures (58%) as destroyed, 90 structures (3%) as damaged, and 1236 (39%) as unaffected. We observed a range of damage states, affected by the structural typology and hazard characteristics. Our study reveals that structures may be damaged or destroyed beyond the lava flow margin, due to thermal effects from the lava flow, fire spread, or from exposure to a range of hazards associated with fissure eruptions, such as steam, volcanic gases, or tephra fall. This study provides a major contribution to the currently limited evidence base required to forecast future lava flow impacts and assess risk.

Hawaii↗

USGS2022

Earthquake scenario selection for portfolio holders in CEUS: A case study with Oklahoma DOT

Portfolio managers of spatially distributed assets in the central and eastern United States (CEUS) and other low- to moderate seismic hazard regions require scenario-based seismic risk assessment for the purpose of emergency management and planning. Uncertainties regarding the long-term seismicity of the region, unknown faults, and limited historical records complicate the selection of an earthquake scenario. Through a case study with the Oklahoma Department of Transportation (ODOT) and their portfolio of bridges, we look at one such exercise, which consists of two scenario earthquakes: one scenario earthquake selected from the U.S. Geological Survey Building Seismic Safety Commission (BSSC) scenario catalog, a magnitude (M) 7.2 event on the Meers fault, and a second aftershock selected by the consequence-driven earthquake scenario selection (Co-DESS) method. The latter is driven by ODOT’s desired service actions to be included during the earthquake drill; in this case, we identify an earthquake that is likely to trigger inspections for bridges across multiple districts, thereby testing not only inspection protocols but also coordination efforts between district groups. We find that the Co-DESS selected event is smaller in magnitude and offers different geographical options than selection through conventional selection methods, while still meeting necessary consequences for an effective earthquake exercise.

Conference Paper↗

USGS2022

Applying consequence-driven scenario selection to lifelines

We present a new consequence-driven framework for earthquake scenario selection. For emergency managers, utility operators, policy makers, and other stakeholders, a scenario-based seismic risk assessment is often necessary for the purpose of emergency management and planning. In developing a scientifically defensible scenario, stakeholders can simulate a realistic event in order to pre-identify vulnerabilities in the system and support action to address these vulnerabilities. Selecting scenarios is particularly challenging for important population centers and critical infrastructure in stable tectonic environments, such as in the central and eastern United States, where uncertain long-term seismicity and unknown faults offer inadequate constraints. Notably, significant events in these so-called stable regions do occur (e.g., Nahanni, Canada, 1985, M6.9; Tennant Creek, Australia, 1998, M6.7). In regions of low seismicity, even moderate events can be consequential due to the higher vulnerability of buildings typical of such regions when compared to regions of higher seismicity. Furthermore, communicating seismic risk to stakeholders and the general public in these regions can be especially challenging due to the complexities of characterizing the hazard level. This framework has been developed to address these challenges for scenario selection in low seismic hazard regions. In this new approach, the analysis begins instead with the explicit definition of a consequence of concern to the specific stakeholder. This can range from a definition of loss (in lives, dollars, or another metric of interest), or a performance metric for critical infrastructure. The framework leverages United States Geological Survey software to run the hazard and consequence analysis. Driven by this stakeholder-defined consequence, an inversion analysis generates a complete event set of candidate scenarios that could breach this consequence. The final selection of a scenario, or family of scenarios, is then scientifically informed, but not limited by our lack of constraints in characterizing the hazard.

Conference Paper↗