scholarly journals Modelling eruptive event sources in distributed volcanic fields

Volcanica ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 325-343
Author(s):  
Elisabeth Gallant ◽  
Lawrence Cole ◽  
Charles Connor ◽  
Amy Donovan ◽  
Danielle Molisee ◽  
...  
Keyword(s):  
Volcanic Hazard ◽  
Ground Deformation ◽  
Source Parameters ◽  
Volcanic Hazards ◽  
Hazard Models ◽  
Eruptive Event ◽  
Temporal Relationships ◽  
Volcanic Fields ◽  
Spatio Temporal ◽  
Hazard Sources

Vent opening hazard models are routinely used as inputs for assessing distal volcanic hazards (lava flows, tephra fallout) in distributed volcanic fields. These vent opening hazard models have traditionally relied on the location of mapped vents; seldom have they taken into account how vents are linked in space and time. We show that inputs needed to appropriately model distal hazards are fundamentally different than thoses required to model near-vent hazards (ground deformation). We provide a computational model to obtain more appropriate eruptive source parameters (ESPs) for distal volcanic hazard sources and show the utility of our code through three examples. The code's strength is that it links events based on the spatio-temporal relationships of vents through heirarchical clustering. The development of the code and its strenghts and weaknesses are discussed. This work challenges previous ideas about ESPs and we hope this work leads to further improvement in hazard assessment methods.

Quantifying asset and visitor risk at Mt. Taranaki, New Zealand from multiple volcanic hazards

2020 ◽  
Author(s):  
Jonathan Procter ◽  
Stuart Mead ◽  
Mark Bebbington
Keyword(s):  
New Zealand ◽  
Hazard Assessment ◽  
Statistical Models ◽  
Volcanic Hazard ◽  
Source Parameters ◽  
Volcanic Hazards ◽  
Debris Avalanche ◽  
Deterministic Models ◽  
Suitable Alternative ◽  
Input Parameters

<p>We present a probabilistic quantification of multiple volcanic hazards in an assessment of risk to visitors and assets in Egmont National Park, New Zealand. The probability of impact to proposed park infrastructure from volcanic activity (originating from Mt. Taranaki) is quantified using a combination of statistical and numerical techniques. While single (volcanic) hazard assessments typically follow a methodology where the hazard source (e.g. pyroclastic flow, ashfall, debris avalanche) is the focus and defines an area of impact, our multi-volcanic hazard assessment uses a location-centred methodology where critical locations are used to define the range of hazard sources that affect risk over park asset lifetimes. Key to this process is creating fast (i.e. linear/functional) mappings between hazard source parameters such as volume and impact parameters such as depth. These mappings can then be combined with stochastic models to find the probability of input parameters and the probability of eruptions generating these input parameters. For some hazards, such as ash fall, statistical models are available to map intensity to probability. However, mass flow hazards required the use of Gaussian process emulation to develop a computationally cheap surrogate to numerical simulations that can be efficiently sampled for probabilistic hazard assessment. This was a suitable alternative when statistical models for the hazard are unavailable. Our study demonstrates the use of these techniques to integrate stochastic and deterministic models for probabilistic volcano multi-hazard assessment.</p>

scholarly journals MatHaz: a Matlab code to assist with probabilistic spatio-temporal volcanic hazard assessment in distributed volcanic fields

2019 ◽  
Vol 8 (1) ◽  
Author(s):  
Daniel Bertin ◽  
Jan M. Lindsay ◽  
Laura Becerril ◽  
Shane J. Cronin ◽  
Lizette J. Bertin
Keyword(s):  
Hazard Assessment ◽  
Volcanic Hazard ◽  
Matlab Code ◽  
Volcanic Fields ◽  
Spatio Temporal

scholarly journals Near-real-time volcanic cloud monitoring: insights into global explosive volcanic eruptive activity through analysis of Volcanic Ash Advisories

2021 ◽  
Vol 83 (2) ◽  
Author(s):  
S. Engwell ◽  
L. Mastin ◽  
A. Tupper ◽  
J. Kibler ◽  
P. Acethorp ◽  
...  
Keyword(s):  
Real Time ◽  
Volcanic Activity ◽  
Volcanic Ash ◽  
Source Parameters ◽  
Volcanic Eruptions ◽  
Volcanic Hazards ◽  
Process Data ◽  
Cloud Monitoring ◽  
Satellite Sensors ◽  
Volcanic Cloud

AbstractUnderstanding the location, intensity, and likely duration of volcanic hazards is key to reducing risk from volcanic eruptions. Here, we use a novel near-real-time dataset comprising Volcanic Ash Advisories (VAAs) issued over 10 years to investigate global rates and durations of explosive volcanic activity. The VAAs were collected from the nine Volcanic Ash Advisory Centres (VAACs) worldwide. Information extracted allowed analysis of the frequency and type of explosive behaviour, including analysis of key eruption source parameters (ESPs) such as volcanic cloud height and duration. The results reflect changes in the VAA reporting process, data sources, and volcanic activity through time. The data show an increase in the number of VAAs issued since 2015 that cannot be directly correlated to an increase in volcanic activity. Instead, many represent increased observations, including improved capability to detect low- to mid-level volcanic clouds (FL101–FL200, 3–6 km asl), by higher temporal, spatial, and spectral resolution satellite sensors. Comparison of ESP data extracted from the VAAs with the Mastin et al. (J Volcanol Geotherm Res 186:10–21, 2009a) database shows that traditional assumptions used in the classification of volcanoes could be much simplified for operational use. The analysis highlights the VAA data as an exceptional resource documenting global volcanic activity on timescales that complement more widely used eruption datasets.

scholarly journals Bootstrap joint prediction regions for sequences of missing values in spatio-temporal datasets

2021 ◽  
Author(s):  
Maria Lucia Parrella ◽  
Giuseppina Albano ◽  
Cira Perna ◽  
Michele La Rocca
Keyword(s):  
Missing Data ◽  
Missing Values ◽  
Sample Selection ◽  
Sample Path ◽  
Temporal Relationships ◽  
Empirical Performance ◽  
Spatio Temporal ◽  
Joint Prediction ◽  
Point Forecast ◽  
Prediction Regions

AbstractMissing data reconstruction is a critical step in the analysis and mining of spatio-temporal data. However, few studies comprehensively consider missing data patterns, sample selection and spatio-temporal relationships. To take into account the uncertainty in the point forecast, some prediction intervals may be of interest. In particular, for (possibly long) missing sequences of consecutive time points, joint prediction regions are desirable. In this paper we propose a bootstrap resampling scheme to construct joint prediction regions that approximately contain missing paths of a time components in a spatio-temporal framework, with global probability $$1-\alpha $$ 1 - α . In many applications, considering the coverage of the whole missing sample-path might appear too restrictive. To perceive more informative inference, we also derive smaller joint prediction regions that only contain all elements of missing paths up to a small number k of them with probability $$1-\alpha $$ 1 - α . A simulation experiment is performed to validate the empirical performance of the proposed joint bootstrap prediction and to compare it with some alternative procedures based on a simple nominal coverage correction, loosely inspired by the Bonferroni approach, which are expected to work well standard scenarios.

Comprehensive palaeomagnetic study of San Borja and Jaraguay monogenetic volcanic fields, Baja California (28–30° N): considerations on latitudinal corrections

2021 ◽  
Author(s):  
A N Mahgoub ◽  
B I García-Amador ◽  
L M Alva-Valdivia
Keyword(s):  
Dipole Moment ◽  
Late Miocene ◽  
Baja California ◽  
Temporal Distribution ◽  
Magnetic Minerals ◽  
Kinematic Evolution ◽  
Oxidation Reduction ◽  
Volcanic Fields ◽  
Spatio Temporal ◽  
Northwestern Mexico

Summary We report 24 palaeomagnetic directions and 10 high-quality Thellier-derived palaeointensity (PI) values, obtained from 27 sites located in Baja California Peninsula, northwestern Mexico. Sampling was done in four rock units (magnesian andesites, calc-alkaline lavas, ignimbrites, adakites) belonging to San Borja and Jaraguay monogenetic volcanic fields. These units have erupted between ∼ 15 and 2.6 Ma (previous K-Ar and 40Ar/39Ar data); hence results are presented in two consecutive periods: middle-late Miocene and Pliocene. The identified main magnetic minerals in the sampled sites are titanomagnetite, magnetite, and minor hematite, of variable grain size, present as intergrowths or surrounding grains, which reflect varying oxidation/reduction conditions during emplacement of high-temperature magmas. Based on previous geological and geophysical records, the kinematic evolution was carefully considered in the region, allowing for the independent restoration of the palaeoposition of each sampled site. Previous palaeodirections were also evaluated and corrected for tectonic motion in order to combine them with present data. Accordingly, a number of 15 and 36 directional data are used to calculate palaeopole position for Pliocene and middle-late Miocene periods, respectively, selected from a total of 74 data points. Pliocene (Plat = 87.8°, Plong = 147.5°, K = 41.06, A95 = 6.0°) and middle-late Miocene (Plat = 86.0°, Plong = 172.7°, K = 41.08, A95 = 3.8) palaeopole positions, calculated after tectonic corrections, are not statistically different from expected North American reference pole. Tectonic correction for Middle-late Miocene virtual geomagnetic poles plays an important role in reducing the resultant tilting from 2.7° to -0.8°. PI mean were calculated for Pliocene and middle-late Miocene periods at 29.2 ± 9.1 μT and 23.2 ± 6.3 μT, respectively. Compiling global filtered PI data, together with our results, indicates that the strength of the geomagnetic field during middle-late Miocene was weak (virtual dipole moment = 5.0 ± 2.2 × 1022 Am2) compared to Pliocene (6.4 ± 2.8 × 1022 Am2), and also relative to the present-day value (7.6 × 1022 Am2). This indicates the global nature of the low dipole moment during the middle-late Miocene period. However, issues related to the spatio-temporal distribution of PI data still present an obstacle to validating these suggestions; therefore, more reliable data are still needed.

Patterns of Cognitive Test Performance As Functions of the Lateral Localization of Cerebral Abnormalities in the Temporal Lobe

1957 ◽  
Vol 103 (433) ◽  
pp. 758-772 ◽  
Author(s):  
Victor Meyer ◽  
H. Gwynne Jones
Keyword(s):  
Test Performance ◽  
Right Hemisphere ◽  
Cognitive Test ◽  
Temporal Relationships ◽  
Verbal Tasks ◽  
Specific Locus ◽  
Left And Right ◽  
Spatio Temporal ◽  
Cognitive Test Performance ◽  
Lateral Localization

Various investigations into the effects of brain injury on psychological test performance (Weisenburg and McBride, 1935; Patterson and Zangwill, 1944; Anderson, 1951; McFie and Piercy, 1952; Bauer and Becka, 1954; Milner, 1954) suggest the overall conclusion that patients with left hemisphere lesions are relatively poor at verbal tasks, while those with right-sided lesions do worst at practical tasks, particularly the manipulation of spatial or spatio-temporal relationships. Heilbfun's (1956) study confirmed that verbal deficits result from left-sided lesions but his left and right hemisphere groups produced almost identical scores on spatial tests. In so far as these workers paid attention to the specific sites of the lesions, their findings indicate that the pattern of test performance is a function of the hemisphere in which the lesion occurs rather than of its specific locus.

Upper-plate structural controls on the segmentation of the Kefalonia Fault (Ionian Sea, Greece)

2021 ◽  
Author(s):  
Emmanuel Skourtsos ◽  
Haralambos Kranis ◽  
Spyridon Mavroulis ◽  
Efthimios Lekkas
Keyword(s):  
Eastern Mediterranean ◽  
Source Parameters ◽  
Plate Boundary ◽  
Temporal Distribution ◽  
Western Coast ◽  
African Plate ◽  
Plate Structure ◽  
The North ◽  
Macroseismic Effects ◽  
Spatio Temporal

<p>The NNE-SSW, right-lateral Kefalonia Transform Fault (KTF) marks the western termination of the subducting Hellenic slab, which is a part of the oceanic remnant of the African plate. The inception of the KTF, described as a STEP fault, is placed in the Pliocene. KTF is considered to be the most active earthquake source in the Eastern Mediterranean. During the last two decades, four significant earthquakes (M>6.0) have been associated with the KTF. These events are attributed to the reactivation of different segments of the KTF, which are (from North to South) the North Lefkada, South Lefkada, Fiskardo, Paliki and Zakynthos segments: the North Lefkada segment ruptured in the 2003 earthquake, the 2014 Kefalonia events are associated with the Paliki segment and the 2015 Lefkada earthquake with the South Lefkada (and possibly the Fiskardo) segments.</p><p>The upper plate structure in the islands of Lefkada and Kefalonia is characterized by the Ionian Unit, thrusted over the Paxi (or Pre-Apulian) Unit. The Ionian Thrust, which brings the Ionian over the Paxi Unit, is a main upper-plate NNW-SSE, NE-dipping structure. It runs through the island of Lefkada, to be mapped onshore again at the western coast of Ithaki and at SE Kefalonia. Two other major thrusts are mapped on this island: the Aenos thrust, which has a WNW-ESE strike at the southern part of the island and gradually curves towards NNW-SSE in the west and the Kalo Fault in the northern part. These Pliocene (and still active) structures developed during the late-most stages of thrusting in the Hellenides, strike obliquely to the KTF and appear to abut against it.</p><p>We suggest that these thrusts control not only the deformation within the upper plate, but also the earthquake segmentation of the KTF. This suggestion is corroborated by the spatio-temporal distribution and source parameters of the recent, well-documented earthquake events and by the macroseismic effects of these earthquakes. The abutment of the Ionian thrust against the KTF marks the southern termination of the Lefkada earthquake segment, which ruptured in the 2003 earthquake, while the Aenos, (or the Kalo) thrust mark the southern end of the Fiskardo segment. The spatial distribution of the Earthquake Environmental Effects related to the four significant events in the last 20 years displays a good correlation with our interpretation: most of the 2003 macroseismic effects are located in the northern part of Lefkada, which belongs to the upper block of the Ionian thrust; similarly, the effects of the 2014 earthquakes of Kefalonia are distributed mainly in the Paliki Peninsula and the southern part of the island that belong to the footwall of the Aenos thrust and the 2015 effects are found in SW Lefkada, which is part of the footwall of the Ionian thrust.</p><p>We suggest that correlation between upper-plate structure and plate boundary faulting can provide insights in the understanding of faulting pattern in convergent settings, therefore contributing to earthquake management plans.</p>

scholarly journals Spatio-Temporal Variation of Atmospheric Gaseous and Particulate Reactive Nitrogen over Northern India

2021 ◽  
Vol Special Issue (1) ◽  
pp. 53-67
Author(s):  
Manisha Mishra ◽  
Umesh C Kulshrestha
Keyword(s):  
Source Parameters ◽  
Ambient Air ◽  
Water Soluble ◽  
Rural Site ◽  
Urban Site ◽  
Local Source ◽  
Reactive Nitrogen ◽  
Gangetic Plain ◽  
Reactive N ◽  
Spatio Temporal

The present study reports spatio-temporal distribution pattern of major gaseous (NH3 and NO2) and particulate water soluble total nitrogen (pWSTN) in the ambient air to explore the seasonal variation, major interactions and dominating sources. Considering the major hotspot of atmospheric reactive nitrogen (N) emission, three sites in Indo-Gangetic plain (IGP) were selected based on different local source parameters. Results have shown that gas phase reactive N contribute up to 90% of total analyzed reactive N, where NH3 imparted highest at all the three sites. Prayagraj, a fast growing urban site, has shown highest concentrations of NH3 (72.0 μg m−3), followed by Madhupur rural site (57.7 μg m−3) and Delhi, an urban megacity site (35.8 μg m−3). As compared to previous studies conducted at different sites of IGP, NH3 concentrations were reported to be the highest at the former two sites. However, unlike NH3, NO2 levels were recorded lower at Madhupur (3.1 μg m−3) and Prayagraj (9.4 μg m−3) sites as compared to Delhi (13.4 μg m−3). Similarly, pWSTN concentrations were in the order of Madhupur (6.6 μg m−3) < Prayagraj (10.0 μg m−3) < Delhi (10.1 μg m−3). A strong correlation of NO2 with pWSTN at urban sites has shown the crucial role of NO2 in the formation of nitrogenous aerosols. Significant spatial variation can be attributed to varying local emission sources ranging from microbial emission from improper sewage treatment and open waste dumping at Prayagraj, agricultural activities at Madhupur and vehicular exhausts at Delhi site.

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