147 research outputs found
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Modeling the large runup along a narrow segment of the Kaikoura coast, New Zealand following the November 2016 tsunami from a potential landslide
Appendix A. Supplementary data:
The following is the Supplementary data to this article: Download Word document (https://ars.els-cdn.com/content/image/1-s2.0-S0029801818318286-mmc1.docx - 3MB).Copyright © 2019 The Authors. The 2016 Mw 7.8 Kaikoura earthquake and consequent tsunami have been controversial because of uncertainty over whether and where the plate interface ruptured and the incapability of the proposed source models to reproduce the near-field runup of 7 m. Existing models identify a wide range of locations for the interface rupture, from on land to offshore, and fail to reproduce runup of 7 m near Kaikoura. To generate the large tsunami peak in Kaikoura tide gauge record and the observed runup height, offshore seafloor movement is necessary, but the offshore extension of the plate-interface rupture and its type, either seismic rupture or a landslide, is uncertain. Here, we propose a submarine landslide in addition to the earthquake source, with the landslide delayed 10–20 min after the earthquake rupture. The landslide volume is 4.5–5.2 km3, located within 173.7–174.3oE (longitude) and 42.6–42.15oS (latitude). Our proposed dual tsunami source successfully reproduces near-field tide gauge records as well as observed near-field runup height of 7 m. We showed that more accurate source models of earthquakes can be achieved by considering observed runup data through runup inversions in addition to waveform inversions.Brunel Research Initiative and Enterprise Fund 2017/18 (BUL BRIEF) at Brunel University Londo
Application of dense offshore tsunami observations from Ocean Bottom Pressure Gauges (OBPGs) for tsunami research and early warnings
We introduce a new data source of dense deep-ocean tsunami records
7 from Ocean Bottom Pressure Gauges (OBPGs) which are attached to Ocean Bottom
8 Seismometers (OBS) and apply them for far-field and near-field tsunami warnings.
9 Tsunami observations from OBPGs are new sources of deep-ocean tsunami
10 observations which, for the first time, provide dense tsunami data with spacing
11 intervals in the range of 10–50 km. Such dense data are of importance for tsunami
12 research and warnings and are capable of providing new insights into tsunami
13 characteristics. Here, we present a standard procedure for the processing of the
14 OBPG data and extraction of tsunami signals out of these high-frequency data.
15 Then, the procedure is applied to two tsunamis of 15 July 2009 Mw 7.8 Dusky
16 Sound (offshore New Zealand) and 28 October 2012 Mw 7.8 Haida Gwaii (offshore
17 Canada). We successfully extracted 30 and 57 OBPG data for the two aforesaid
18 tsunamis, respectively. Numerical modeling of tsunami was performed for both
19 tsunamis in order to compare the modeling results with observation and to use the
20 modeling results for the calibration of some of the OBPG data. We successfully
21 employed the OBPG data of the 2012 Haida Gwaii tsunami for tsunami forecast by
22 applying a data assimilation technique. Our results, including two case studies,
23 demonstrate the high potential of OBPG data for contribution to tsunami research
24 and warnings. The procedure developed in this study can be readily applied for the
2526 extraction of tsunami signals from OBPG data
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A comparative study of far-field tsunami amplitudes and ocean-wide propagation properties: Insight from major trans-Pacific tsunamis of 2010-2015
Copyright © The Author(s) 2018. We studied ocean-wide propagation properties of four recent trans-Pacific tsunamis based on deep-ocean measurements across the Pacific Ocean. First, we analyzed and simulated the 16 September 2015 tsunami generated by the Illapel (Chile) earthquake (Mw 8.4) and compared its ocean-wide propagation with those of three other events: the 2014 Iquique (Mw 8.2), 2010 Maule (Mw 8.8) and 2011 Tohoku (Mw 9.0). The Illapel and Maule tsunami sources are located close to each other and we reconstructed the source spectrum of the larger (i.e. Maule) tsunami by applying spectral deconvolution using the smaller (i.e. Illapel) tsunami as the empirical Green's function. The initial negative phase was found for all four events with durations of 8–29 (Iquique), 20–35 (Illapel), 22–70 (Maule) and 40–79 (Tohoku) min, with the maximum amplitudes of 0.11–0.26, 0.4–0.7, 0.5–2.9 and 1.9–2.5 cm, and the amplitude ratios to the first elevation phases of 20–40 per cent, 22–41 per cent, 29–61 per cent and 12–67 per cent, respectively. Unlike other studies, our results revealed that the duration ({D_{ini}}$ $) and amplitude ({A_{ini}}) of the initial negative phase are directly proportional to the earthquake magnitude ({M_w}$ $) with equations: {M_w} = \;6.129 + 1.629\;{\rm{log}}( {{D_{ini}}} ) and {M_w} = \;8.676 + 0.706\;{\rm{log}}( {{A_{ini}}} )$ $. No relationships were observed between these parameters (i.e. {D_{ini}} and {A_{ini}}$ $) and distance from the source. The amplitudes of far-field DART waves do not vary with distance or strike angle, and depend only on the {M_w}. The average far-field deep-ocean amplitudes ({A_{tsu}}$ $) for the Iquique, Illapel, Maule and Tohoku tsunamis were 0.9, 1.7, 6.0 and 15.0 cm, respectively, yielding the equation: {M_w} = \;8.245 + 0.665\;{\rm{log}}( {{A_{tsu}}} ).Brunel Research Initiative and Enterprise Fun
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Numerical modeling of the subaerial landslide source of the 22 December 2018 Anak Krakatoa volcanic tsunami, Indonesia
The eruption of the Anak Krakatoa volcano (Indonesia) in December 2018 produced a destructive tsunami with maximum runup of 13 m killing 437 people. Since the occurrence of this rare tsunami, it has been a challenge as how to model this tsunami and to reconstruct the network of coastal observations. Here, we apply a combination of qualitative physical modeling and wavelet analyses of the tsunami as well as numerical modeling to propose a source model. Physical modeling of a volcano flank collapse showed that the initial tsunami wave mostly involves a pure-elevation wave. We identified initial tsunami period of 6.3–8.9 min through Wavelet analysis, leading to an initial tsunami dimension of 1.8–7.4 km. Twelve source models were numerically modelled with source dimensions of 1.5–4 km and initial tsunami amplitudes of 10–200 m. Based on the qualities of spectral and amplitude fits between observations and simulations, we constrained the tsunami source dimension and initial amplitude in the ranges of 1.5–2.5 km and 100–150 m, respectively. Our best source model involves potential energy of 7.14 × 1013–1.05 × 1014 J equivalent to an earthquake of magnitude 6.0–6.1. The amplitude of the final source model is consistent with the predictions obtained from published empirical equations.Royal Society, Great Britain Sasakawa Foundatio
The Science of Sungrazers, Sunskirters, and Other Near-Sun Comets
This review addresses our current understanding of comets that venture close to the Sun, and are hence exposed to much more extreme conditions than comets that are typically studied from Earth. The extreme solar heating and plasma environments that these objects encounter change many aspects of their behaviour, thus yielding valuable information on both the comets themselves that complements other data we have on primitive solar system bodies, as well as on the near-solar environment which they traverse. We propose clear definitions for these comets: We use the term near-Sun comets to encompass all objects that pass sunward of the perihelion distance of planet Mercury (0.307 AU). Sunskirters are defined as objects that pass within 33 solar radii of the Sun’s centre, equal to half of Mercury’s perihelion distance, and the commonly-used phrase sungrazers to be objects that reach perihelion within 3.45 solar radii, i.e. the fluid Roche limit. Finally, comets with orbits that intersect the solar photosphere are termed sundivers. We summarize past studies of these objects, as well as the instruments and facilities used to study them, including space-based platforms that have led to a recent revolution in the quantity and quality of relevant observations. Relevant comet populations are described, including the Kreutz, Marsden, Kracht, and Meyer groups, near-Sun asteroids, and a brief discussion of their origins. The importance of light curves and the clues they provide on cometary composition are emphasized, together with what information has been gleaned about nucleus parameters, including the sizes and masses of objects and their families, and their tensile strengths. The physical processes occurring at these objects are considered in some detail, including the disruption of nuclei, sublimation, and ionisation, and we consider the mass, momentum, and energy loss of comets in the corona and those that venture to lower altitudes. The different components of comae and tails are described, including dust, neutral and ionised gases, their chemical reactions, and their contributions to the near-Sun environment. Comet-solar wind interactions are discussed, including the use of comets as probes of solar wind and coronal conditions in their vicinities. We address the relevance of work on comets near the Sun to similar objects orbiting other stars, and conclude with a discussion of future directions for the field and the planned ground- and space-based facilities that will allow us to address those science topics
Coupled, Physics-Based Modeling Reveals Earthquake Displacements are Critical to the 2018 Palu, Sulawesi Tsunami
The September 2018, Mw 7.5 Sulawesi earthquake occurring on the Palu-Koro strike-slip fault system was followed by an unexpected localized tsunami. We show that direct earthquake-induced uplift and subsidence could have sourced the observed tsunami within Palu Bay. To this end, we use a physics-based, coupled earthquake–tsunami modeling framework tightly constrained by observations. The model combines rupture dynamics, seismic wave propagation, tsunami propagation and inundation. The earthquake scenario, featuring sustained supershear rupture propagation, matches key observed earthquake characteristics, including the moment magnitude, rupture duration, fault plane solution, teleseismic waveforms and inferred horizontal ground displacements. The remote stress regime reflecting regional transtension applied in the model produces a combination of up to 6 m left-lateral slip and up to 2 m normal slip on the straight fault segment dipping 65∘ East beneath Palu Bay. The time-dependent, 3D seafloor displacements are translated into bathymetry perturbations with a mean vertical offset of 1.5 m across the submarine fault segment. This sources a tsunami with wave amplitudes and periods that match those measured at the Pantoloan wave gauge and inundation that reproduces observations from field surveys. We conclude that a source related to earthquake displacements is probable and that landsliding may not have been the primary source of the tsunami. These results have important implications for submarine strike-slip fault systems worldwide. Physics-based modeling offers rapid response specifically in tectonic settings that are currently underrepresented in operational tsunami hazard assessment
Consensus Middle East and North Africa Registry on Inborn Errors of Immunity
Background: Inborn errors of immunity (IEIs) are a heterogeneous group of genetic defects of immunity, which cause high rates of morbidity and mortality mainly among children due to infectious and non-infectious complications. The IEI burden has been critically underestimated in countries from middle- and low-income regions and the majority of patients with IEI in these regions lack a molecular diagnosis. Methods: We analyzed the clinical, immunologic, and genetic data of IEI patients from 22 countries in the Middle East and North Africa (MENA) region. The data was collected from national registries and diverse databases such as the Asian Pacific Society for Immunodeficiencies (APSID) registry, African Society for Immunodeficiencies (ASID) registry, Jeffrey Modell Foundation (JMF) registry, J Project centers, and International Consortium on Immune Deficiency (ICID) centers. Results: We identified 17,120 patients with IEI, among which females represented 39.4%. Parental consanguinity was present in 60.5% of cases and 27.3% of the patients were from families with a confirmed previous family history of IEI. The median age of patients at the onset of disease was 36 months and the median delay in diagnosis was 41 months. The rate of registered IEI patients ranges between 0.02 and 7.58 per 100,000 population, and the lowest rates were in countries with the highest rates of disability-adjusted life years (DALY) and death rates for children. Predominantly antibody deficiencies were the most frequent IEI entities diagnosed in 41.2% of the cohort. Among 5871 patients genetically evaluated, the diagnostic yield was 83% with the majority (65.2%) having autosomal recessive defects. The mortality rate was the highest in patients with non-syndromic combined immunodeficiency (51.7%, median age: 3.5 years) and particularly in patients with mutations in specific genes associated with this phenotype (RFXANK, RAG1, and IL2RG). Conclusions: This comprehensive registry highlights the importance of a detailed investigation of IEI patients in the MENA region. The high yield of genetic diagnosis of IEI in this region has important implications for prevention, prognosis, treatment, and resource allocation
Monogenic Primary Immunodeficiency Disorder Associated with Common Variable Immunodeficiency and Autoimmunity
Background: Common variable immunodeficiency (CVID) is the most frequent primary immunodeficiency disorder mainly characterized by recurrent bacterial infections besides other immunological defects including loss of or dysfunction of B cells and decreased immunoglobulin levels. In this study, our aim is to evaluate clinical, immunological, and molecular data of patients with a primary clinical diagnosis of CVID and autoimmune phenotype with a confirmed genetic diagnosis. Methods: Among 297 patients with CVID, who were registered in the Iranian Primary Immunodeficiency Registry at Children's Medical Center Hospital in Iran, 83 patients have been genetically examined and 27 patients with autoimmunity and confirmed genetic mutations were selected for analysis. Whole-exome sequencing and confirmatory Sanger sequencing methods were used for the study population. A questionnaire was retrospectively filled for all patients to evaluate demographic, laboratory, clinical, and genetic data. Results: In the 27 studied patients, 11 different genetic defects were identified, and the most common mutated gene was LRBA, reported in 17 (63.0) patients. Two patients (7.7) showed autoimmune complications as the first presentation of immunodeficiency. Eleven patients (40.7) developed one type of autoimmunity, and 16 patients (59.3) progressed to poly-autoimmunity. Most of the patients with mono-autoimmunity (n = 9, 90.0) primarily developed infectious complications, while in patients with poly-autoimmunity, the most common first presentation was enteropathy (n = 6, 37.6). In 13 patients (61.9), the diagnosis of autoimmune disorders preceded the diagnosis of primary immunodeficiency. The most frequent autoimmune manifestations were hematologic (40.7), gastrointestinal (48.1), rheumatologic (25.9), and dermatologic (22.2) disorders. Patients with poly-autoimmunity had lower regulatory T cells than patients with mono-autoimmunity. Conclusion: In our cohort, the diagnosis of autoimmune disorders preceded the diagnosis of primary immunodeficiency in most patients. This association highlights the fact that patients referring with autoimmune manifestations should be evaluated for humoral immunity. © 2020 Georg Thieme Verlag. All rights reserved
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