Browsing by Author "Bebbington M"
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- ItemA new perspective on eruption data completeness: insights from the First Recorded EruptionS in the Holocene (FRESH) database(Elsevier BV, 2022-11) Burgos V; Jenkins SF; Bebbington M; Newhall C; Taisne BIdentifying the most complete (best recorded) portion of an eruption record is essential before estimating eruption recurrence and probability. This is typically achieved by plotting cumulative eruptions through time. Here, we evaluate eruption data completeness from a new perspective, by compiling the first dated Holocene eruption from each volcano in the Volcanoes of the World (VOTW) database (i.e., First Recorded EruptionS in the Holocene (FRESH)). In our first analysis, we compared the subregional distribution of FRESH with time using Kolmogorov-Smirnov (K[sbnd]S) test. We found that the eruption record was best categorised into 31 regions containing subregions with similar degrees of completeness. This opened the way to define new Relative Completeness Date(s) (RCD) as a function of eruption size, volcanic characteristics, and region, by identifying multiple points in the record where the root-mean-square (RMS) level changes abruptly, corresponding to a gap, a decrease or increase in the FRESH rate. Regional RCDs in the Common Era (CE) range from as recently as 1964 CE in the Indian Ocean (southern) to 200 CE in Middle East and Western Indian Ocean. In contrast, some regions like Kamchatka and Mainland Asia have near-constant rates of FRESH over the last 12,000 years, making RCDs impossible to assign. We present and make available our FRESH database, and describe and implement an automatic approach to detect RCDs across our newly defined volcanic regions. We suggest that the different degrees of completeness observed at a regional scale can be explained by: socio-historical events, access to geological studies, submarine volcanism, and/or remoteness. The FRESH database, together with the new regions and proposed RCDs can be used in future studies to estimate eruption probabilities at volcanoes without Holocene records and identify which subregions are most likely to produce a FRESH in the future.
- ItemA Statistical Model for Earthquake And/Or Rainfall Triggered Landslides(Frontiers Media S.A., 2021-02-04) Frigerio Porta G; Bebbington M; Xiao X; Jones G; Xu CNatural hazards can be initiated by different types of triggering events. For landslides, the triggering events are predominantly earthquakes and rainfall. However, risk analysis commonly focuses on a single mechanism, without considering possible interactions between the primary triggering events. Spatial modeling of landslide susceptibility (suppressing temporal dependence), or tailoring models to specific areas and events are not sufficient to understand the risk produced by interacting causes. More elaborate models with interactions, capable of capturing direct or indirect triggering of secondary hazards, are required. By discretising space, we create a daily-spatio-temporal hazard model to evaluate the relative and combined effects on landslide triggering due to earthquakes and rainfall. A case study on the Italian region of Emilia-Romagna is presented, which suggests these triggering effects are best modeled as additive. This paper demonstrates how point processes can be used to model the triggering influence of multiple factors in a large real dataset collected from various sources.
- ItemDevelopment of a Bayesian event tree for short-term eruption onset forecasting at Taupō volcano(Elsevier BV, 2022-12) Scott E; Bebbington M; Wilson T; Kennedy B; Leonard GTaupō volcano, located within the Taupō Volcanic Zone (TVZ) in the central North Island of Aotearoa-New Zealand, is one of the world's most active silicic caldera systems. Silicic calderas such as Taupō are capable of a broad and complex range of volcanological activity, ranging from minor unrest episodes to large destructive supereruptions. A critical tool for volcanic risk management is eruption forecasting. The Bayesian Event Tree for Eruption Forecasting (BET_EF) is one probabilistic eruption forecasting tool that can be used to produce short-term eruption forecasts for any volcano worldwide. A BET_EF model is developed for Taupō volcano, informed by geologic and historic data. Monitoring parameters for the model were obtained through a structured expert elicitation workshop with 30 of Aotearoa-New Zealand's volcanologists and volcano monitoring scientists. The eruption probabilities output by the BET_EF model for Taupō volcano's 17 recorded unrest episodes (between 1877 and 2019) were examined. We found time-inhomogeneity in the probabilities stemming from both the changes over time in the monitoring network around Taupō volcano and increasing level of past data (number of non-eruptive unrest episodes). We examine the former issue through the lens of the latest episodes, and the latter by re-running the episodes assuming knowledge of all 16 other episodes (calibration to 2021 data). The time variable monitoring network around Taupō volcano and parameter weights had a substantial impact on the estimated probabilities of magmatic unrest and eruption. We also note the need for improved monitoring and data processing at Taupō volcano, the existence of which would prompt updates and therefore refinements in the BET_EF model.
- ItemForecasting Eruptions at Poorly Known Volcanoes Using Analogs and Multivariate Renewal Processes(John Wiley and Sons, Inc on behalf of the American Geophysical Union, 2022-06-28) Wang T; Bebbington M; Cronin S; Carman JForecasting future destructive eruptions from re-awakening volcanoes remains a challenge, mainly due to a lack of previous event data. This sparks a search for similar volcanoes to provide additional information, especially those with better compiled and understood event records. However, we show that some of the most obviously geologically comparable volcanoes have differing statistical occurrence patterns. Using such matches produces large forecasting uncertainties. We created a statistical tool to identify and test the compatibility of potential analogue volcanoes based on repose-time characteristics from world-wide datasets. Selecting analogue volcanoes with compatible behavior for factors being forecast, such as repose time, significantly reduces forecasting uncertainties. Applying this tool to Tongariro volcano (NZ), there is a 5% probability for a Volcanic Explosivity Index (VEI) ≥ 3 explosive eruption in the next 50 years. Using pre-historic geological records of a smaller available set of analogs, we forecast a 1% probability of a VEI ≥ 4 eruption in the next 50 years.
- ItemWhat is the probability of unexpected eruptions from potentially active volcanoes or regions?(Springer Nature Switzerland AG on behalf of the International Association of Volcanology and Chemistry of the Earth's Interior, 2022-11) Burgos V; Jenkins SF; Bebbington M; Newhall C; Taisne B; Sandri LSince the start of the twentieth century, 101 potentially active volcanoes have produced their first Holocene eruption, as recorded in the volcanoes of the world (VOTW) database. The reactivation of potentially active volcanoes is often a surprise, since they tend to be less well-studied and unmonitored. The first step towards preparing for these unexpected eruptions is to establish how often potentially active volcanoes have erupted in the past. Here, we use our previously developed FRESH (First Recorded EruptionS in the Holocene) database to estimate the past regional Average Recurrence Interval (ARI) of these unexpected events. Within the most complete portions of the FRESH database, a FRESH (i.e., the first recorded eruption from a potentially active volcano) has occurred as frequently as every ~ 7 years in the Pacific Ocean region (~ 50 years of relatively complete record) and ~ 8 years in Izu, Volcano, and the Mariana Islands region (~ 150 years of relatively complete record). We use the regional frequency to estimate the annual probability of a FRESH at individual potentially active volcanoes in selected regions of Asia–Pacific, which ranged from 0.003 for Izu, Volcano, and Mariana Islands to 1.35 × 10−5 for Luzon. Population exposure around potentially active volcanoes showed that at volcanoes such as Kendeng (Indonesia) and Laguna Caldera (Philippines), more than 30 million people reside within 100 km of the summit. With this work, we hope to establish how often potentially active volcanoes erupt, while identifying which regions and which potentially active volcanoes may require more attention.