Pure and Applied Geophysics

Kozubek, Michal; Krizan, Peter; Ramatheerthan, Sunil Kumar; Laštovička, Jan

doi: 10.1007/s00024-024-03546-5pmid: N/A

Polar stratospheric chemistry is highly sensitive to changes in water vapor content and temperature. We identified an unusual behavior of water vapor and temperature in the southern polar winter stratosphere in 2023. The relationships between the Hunga-Tonga eruption injection of water vapor (detected in the tropics) and its transport to SH high latitudes, temperature changes and ozone anomalies at southern high latitudes are discussed, as well as the roles of zonal wind and the meridional flux of zonal mean zonal momentum. These parameters exhibit a consistent pattern in anomalous year 2023. In the winter of 2023 in the Southern Hemisphere, an unexpected decrease in ozone levels and the emergence of an excessive ozone hole were observed. This event marked one of the deepest Antarctic ozone holes with the largest area since 2011. This appears to be associated with the Hunga Tonga eruption anomalous water vapor injection. This study highlights importance of water vapor for evolution of the Antarctic stratosphere.

Domnin, Dmitry; Kileso, Aleksandr; Kulmanov, Kirill; Rachipa, Vladislavs

doi: 10.1007/s00024-024-03526-9pmid: N/A

A total of 25 storms were recorded in the autumn–winter period of 2023–2024, with eight of these exhibiting a notable impact on the coast of the South-Eastern Baltic. As a consequence of this phenomenon, the western coast of the Sambian Peninsula of the Kaliningrad Oblast (Russia) was subjected to devastating effects: partial washout of the beach, flooded recreational infrastructure, the direction of the water flow changed and the formation of a local canyon, the dam of a flooded quarry broke through and was completely destroyed. The methodology for the integrated use of field measurement data, meteorological and hydrological information, re-analysis data, as well as satellite images was developed in order to analyses the effects of storms on inland coastal water bodies. Almost all storm events caused sea levels to rise, which had a devastating effect on the coast. As a consequence of the initial storm in October 2023, the inland water body was entirely obliterated, first becoming part of the sea and then a sandy beach. The most significant event was a series of storms in January and February 2024, which resulted in a 90 cm increase in the level rise relative to the pre-storm period. The storms brought with them a vast amount of precipitation, amounting to 51% of the total during the cold period. Rising sea levels and heavy precipitation caused the flooding of coastal lagoon lakes, changes in their thermohaline and oxygen regimes, as well as flooding of adjacent infrastructure.

Williams, James H.; Paulik, Ryan; Aránguiz, Rafael; Wild, Alec

doi: 10.1007/s00024-024-03550-9pmid: N/A

This study assesses physical infrastructure vulnerability for infrastructure network components exposed during the 2015 Illapel tsunami in Coquimbo, Chile. We analyse road and utility pole vulnerability to damage, based on interpolated and simulated tsunami hazard intensity (flow depth, flow velocity, hydrodynamic force and momentum flux) and network component characteristics. A Random Forest Model and Spearman’s Rank correlation test are applied to analyse variable importance and monotonic relationships, with respect to damage, between tsunami hazards and network component attributes. These models and tests reveal that flow depth correlates higher with damage, relative to flow velocity, hydrodynamic force and momentum flux. Scour (for roads and utility poles) and debris strikes (for utility poles) are strongly correlated with damage. A cumulative link model methodology is used to fit fragility curves. These fragility curves reveal that, in response to flow depth, Coquimbo roads have higher vulnerability than those analysed in previous tsunami event studies, while utility poles demonstrate lower vulnerability than with previous studies. Although we identify tsunami flow depth as the most important hydrodynamic hazard intensity metric, for causing road and utility pole damage, multiple characteristics correlate with damage and should also be considered when classifying infrastructure damage levels.

Kumar, M. Senthil; Venkatanathan, N.

doi: 10.1007/s00024-024-03533-wpmid: N/A

Although many earthquake precursors have been proposed to forecast earthquakes, even in this modern era, short-term earthquake forecasting remains challenging due to the heterogeneous nature of the earthquake’s occurrence. This study mainly focused on how the impending earthquake influences pre-earthquake scenarios using minor shocks and further confirmed by atmospheric parameters such as Outgoing Longwave Radiation (OLR). The Himalayan belt is one of the most at-risk areas during a continental-continental collision. The spatiotemporal analysis of the pre-earthquake scenario is carried out to identify the most vulnerable seismic risk zone and to forecast the probable magnitude of the earthquake. From the analysis, it is found that the accumulation of strain energy focussing near the epicenter of the impending earthquake. Furthermore, the study also revealed that abnormal changes in atmospheric parameters observed several days before an earthquake, which could serve as a precursor of seismic activity. On certain days, the anomalous OLR due to the radon gas emanation was observed at the different locations around the epicenter of the impending earthquakes. This phenomenon probably due to the transfer of accumulated strain from one side of the fault to other side of the fault through epicenter of the impending earthquake. This gives vital clue in determining the possible epicenter of the earthquake. The statistical analysis of minor shocks associated with significant earthquakes made it possible to determine the magnitude and depth range of minor shocks that may trigger the nucleation process for major earthquakes. The magnitude and depth ranges of microshocks involved in the nucleation process differed among fault types. This research highlights the importance of monitoring seismic and atmospheric activity to improve earthquake forecasting and preparedness. Hence, it is possible to identify the most vulnerable seismic zone, location of the epicenter and probable magnitude spatio-temporal analysis.

Sharma, Vickey; Biswas, Rajib

doi: 10.1007/s00024-024-03530-zpmid: N/A

This study explores the feasibility of using fluctuations in the recurrence magnitude dispersion factor (b-value) as a seismic precursor for the Mizoram earthquake that occurred on November 26, 2021, in the Indo-Burma region of northeast India. Employing a comprehensive and homogeneous earthquake catalog spanning from 1900 to 2020, the seismic analysis involved delustering and completeness testing. The research implements a sub-sectional b-value calculation method, dividing the study area into uniformly sized grid cells (2° × 2°) and performing temporal b-value mapping for each grid. The epicenter of the Mizoram earthquake was located within a grid cell characterized by an intermediate b-value. Time-series analysis of the b-value indicated a notable decline preceding the main event, suggesting its potential as a seismic precursor. The study also examines depth-dependent variations in the b-value, revealing an inverse relationship between the b-value and crustal stress. To evaluate the significance of b-value anomalies, the Kolmogorov–Smirnov (K-S) statistic was employed instead of visual inspection. Additionally, the research provides probabilistic estimates of seismic hazard parameters, including the most probable maximum yearly earthquake, mean return period, and probabilities of earthquakes of varying magnitudes. These findings contribute to a deeper understanding of the complex seismotectonic framework and high lithospheric variability in the investigated region.

Nava, F. A.; Gutiérrez, Q. J.

doi: 10.1007/s00024-024-03534-9pmid: N/A

A crisp step function is not an adequate threshold for studies of Markovian occurrence of large earthquakes, because it can lead to missing or pseudo links in an observed sequence that should be a Markov chain. A more realistic threshold is a fuzzy one where there is a transition magnitude band, located between those magnitudes that are too small for the earthquakes to be part of a Markovian process and those who are certainly large enough for the earthquakes to be part of it, where earthquakes may or may not be part of the process. This fuzzy threshold is described by a membership function that gives the probability of an earthquake with a given magnitude belonging to the process. We propose a membership function with probabilities in the transition band proportional to the seismic moment. To estimate empirical transition probabilities when considering a fuzzy magnitude threshold, we propose a counting strategy for the observed transitions and justify it through Monte Carlo simulations. The counting strategy is illustrated by application to the model from a previous seismic study of the Japan area by testing, through Monte Carlo simulations, how well the counting strategy results resemble optimum estimations of the transition probabilities. The simulations are also used to study the behavior of three Markovianity measures, and it is found that the peak values of these measures are not useful in identifying the true transition band, but that this band may be better identified by using the whole set of values taken by each measure for different transition band models. As an illustration, the measures were applied to real data from the previous study, a short set corresponding to a single realization, and found that the behavior of the measures does not agree with those expected from a crisp threshold, but agree, within the limitations of the data, with either a fuzzy threshold going from zero probability for magnitudes M≤6.9\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$M\le 6.9$$\end{document} to probability one for M≥7.2\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$M\ge 7.2$$\end{document} or from zero probability for magnitudes M≤7.0\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$M\le 7.0$$\end{document} to probability one for M≥7.2\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$M\ge 7.2$$\end{document}.

Asanulla, R. Mohamed; Radhakrishna, T.; Bansal, B. K.; Ramakrishna, Ch.

doi: 10.1007/s00024-024-03538-5pmid: N/A

Thermal Thellier type palaeointensity (PI) experiments are the most popular technique in determining strength of the past geomagnetic field (GMF). However, the method often encounters high failure rate. Mineral magnetic properties can provide useful information to enhance the success rate. We conducted the first ever detailed mineral magnetic and Thellier type PI experiments on lava flows within a 1250 m stratigraphic section of the largest end-Cretaceous (~ 65–66 Ma) Deccan flood basalt. The lava flows mostly contain pseudo single domain (PSD) titano-magnetite/magnetite with, low viscosity index (≤ 5), high/moderate Koenigsberger ratio (Qn > 10/ < 10), isothermal remanent magnetisation parameters typical of ferromagnetic minerals, saturation remanence magnetization to saturation magnetization ratio (Mrs/Ms: 0.05–0.31), coercivity of remanence to coercive force ratio (Hcr/Hc: 1.53–3.72) and a single magnetic component pointing to origin or a minor viscous component during alternating field (AF) demagnetizations,. Their thermomagnetic responses are broadly group into 3 categories. The type 1 displays near perfect reversible heating/cooling curves with high Curie temperatures of 570–600 °C; other two types have either widely separated (type2) or quite dissimilar (type 3) heating/cooling curves. 76 samples from 19 flows were subjected to ZI (Zero field-Infield) experiments with pTRM and pTRM tail checks. 24 samples from eight flows display reasonable NRM-TRM linearity and positive pTRM checks and satisfy strict reliability criteria. 42 samples from 11 flows do not satisfy the reliability criteria. Samples of reliable PI results are all characterized by reversible thermomagnetic behaviour with excellent stability during AF/thermal treatment. Samples that failed to meet reliability criteria possess irreversible/widely separated thermomagnetic heating/cooling curves or poor stability to AF/thermal treatment but not significantly different from the successful samples in other magnetic properties. Thus, thermomagnetic behaviour and stability to AF/thermal treatment appear to be the overweighing factors than other mineral magnetic characteristics that govern the success rate of thermal PI experiments. The PI values of upper normal (29N) flows are relatively higher than the lower reverse (29R) flows; this suggests minor time lag in cooling of successive flows. The time averaged PI estimate is an important end-Cretaceous contribution from the Indian subcontinent to the poorly represented database of southern hemisphere.

Bortolozo, Cassiano Antonio; Campaña, Julian David Realpe; Santos, Fernando Acácio Monteiro Dos; De Oliveira, Gabriela Serejo; Porsani, Jorge Luís; Pryer, Tristan; Sialounas, Georgios

doi: 10.1007/s00024-024-03529-6pmid: N/A

In this study, we present a new methodology for 2D joint inversion, or data fusion, of DC electro-resistivity and Transient Electromagnetic methods. These geophysical techniques have traditionally been used separately, but by combining them, we aim to decrease ambiguities and increase the robustness of the resulting subsurface model. The inversion process was conducted using the classical Occam method with smooth models and synthetic studies were also conducted to understand the limitations and advantages of the method. We also applied the algorithm to data obtained in groundwater exploration in Brazil, and the results showed that the 2D joint inversion is promising in increasing accuracy and reducing ambiguity in subsurface imaging.

Jose, Vibin; Chandrasekar, Anantharaman; Reddy Rodda, Suraj

doi: 10.1007/s00024-024-03523-ypmid: N/A

The present study has employed a regional Land Surface Model (LSM) to investigate the impact of historical land cover changes on land surface characteristics over the Indian subcontinent for the period of 1930–2013. Four simulations that include a control run and three experiment runs are performed with the Noah 3.6 LSM within the Land Information System (LIS). In the present study, the Noah LSM is driven by meteorological forcings, with radiation data obtained from the Global Data Assimilation System (GDAS) and the rainfall data obtained from IMD gridded rainfall data. The control run is performed with a MODIS-IGBP land cover map, while the three experimental runs are performed with three different potential land cover maps for the years 1930, 1975, and 2013. The potential land cover maps for the above three simulations are developed by blending the MODIS-IGBP data set with the fractional forest cover data set; the latter data is available for the years 1930, 1975, and 2013. Results indicate that the historical land cover change (1930 to 2013) has reduced the annual mean of latent heat flux and net surface heat flux over the Indian domain by -\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$-$$\end{document}24.74 W/m2\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$W/m^2$$\end{document} and -\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$-$$\end{document}14.18 W/m2\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$W/m^2$$\end{document} respectively, while the sensible heat flux and the soil temperature has increased by 4.97 W/m2\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$W/m^2$$\end{document} and 2.78 K. The annual mean change in latent heat flux, sensible heat flux, and soil temperature demonstrate that the largest changes occur when the land cover changes from forest to urban land as compared to forest to cropland, forest to grassland and forest to open shrubland. The annual mean change in latent heat flux is moderately large for the land cover change from forest to open shrubland when compared to forest to grassland and forest to cropland. The above is attributed to the effects of evapotranspiration, which has high values for the cropland followed by grassland and open shrubland. Furthermore, the triple collocation method is employed to assess the impact of historical land cover change on soil moisture. Results indicate that the triple collocation method effectively demonstrates the impact of land cover change on soil moisture.

Sisodiya, Anshul; Pattnaik, Sandeep; Baneerjee, Adrish

doi: 10.1007/s00024-024-03547-4pmid: N/A

Selecting proper parameterization scheme combinations for a particular application is of great interest to Weather Research and Forecasting (WRF) model users. The goal of this research is to create an objective method for identifying a set of scheme combinations to form a Multi-Physics Ensemble (MPE) suitable for short-term precipitation forecasting over Odisha, India’s east coast state. In this study, five member ensembles for Cloud Microphysics (CMP) and Land Surface Model (LSM, conventional ensemble) are created, as well as an ensemble of the top five performing members (optimized ensemble) for 13 Monsoon Depressions (MD) and 8 Deep Depression (DD) cases. There are a total of 30 combinations (5 PBL * 5 CMP, 5 LSM with best PBL and CMP, and one with ISRO Land Use Land Cover data). WRF 4.1 is used to carry out simulations, which are initialized with ERA5 reanalysis data and have a 72-h lead time. Rainfall verification skill scores indicate that ensemble members perform significantly better than any deterministic model. Rainfall characteristics such as location, intensity, and time of occurrence are well predicted in ensemble members as measured by a higher correlation coefficient and a lower RMSE. Neighbourhood ensemble probability also demonstrates that ensemble members have a higher chance of detecting heavy to very heavy rainfall events with more spatial accuracy. The study also concludes that choice of parameterization also affects large-scale dynamical parameters (temperature, humidity, wind, hydrometeors) and thus associated rainfall. Ensemble members exhibited less bias in the composite analysis of large-scale parameters. Furthermore, a composite analysis of moisture budget components revealed that the convergence term is the most important component of moisture accumulation, resulting in rainfall during the monsoon low-pressure system. These findings indicate that the proposed method is an effective method for reducing bias in rainfall forecasts.