Space-time Anomalies Research Articles

Thermal Infrared Anomalies Associated with Recent Crustal Earthquakes in Gorj County in Romania

Cumulative stress-energy in tectonic active regions associated with ongoing deformation (co-seismic stress) along the main active geologic faults manifests various earthquakes’ precursors. Macro-fracturing processes are preceded by micro-fracturing phenomena which amplify strain field, and geophysical fields’ disturbances like space-time anomalies of Earth’s fracto-emission signals (Thermal; Ionospheric; Electric Field; Acoustic; Radon in air, underground water, and soil; Neutron, etc.) registered months to days before the occurrence of earthquakes. Multispectral and multisensor time series satellite data and space-based geodetic (GPS and GNSS) measurements in synergy with ground-based geophysical/geochemical measurements bring a significant contribution to survey pre-earthquake signals in the tectonic active areas. This study aims to assess the role of seismo-induced thermal infrared (TIR) anomalies characterized by the ground-level air-AT and land surface temperature-LST changes as significant precursors of crustal moderate and strong earthquakes recorded in Gorj County, Oltenia region in Romania. North-West Targu Jiu area is an active tectonic area characterized by two strike-slip faults systems of North-West- South West and East-West orientation, where on 13 February 2023 was recorded a shallow strong earthquake of moment magnitude Mw= 5.2 and 17 km focal depth, followed by 14 February 2023 stronger earthquake of Mw = 5.7 and 6 km focal depth. Several months beyond have been recorded more than 1000 aftershocks of Mw ≤ 4.9. Based on MODIS Terra/Aqua and NOAA AVHRR time series data, some days to weeks before the seismic sequence has detected LST and AT anomalies.

SLOW DEFORMATION WAVES IN THE SEISMIC REGIME AND GEOPHYSICAL FIELDS AT THE NORTHERN MARGIN OF THE AMUR PLATE

The interaction between the Amur, Pacific and Eurasian tectonic plates initiates seismic activity at the plate margins as well as in the plate periphery, as evidenced by intracontinental earthquakes. In the Amur plate, the dynamics of intercontinental seismicity is controlled by deformation wave fronts comprising a regular pattern of equidistant zones [Sherman, 2013]. According to [Trofimenko et al., 2015a, 2015b, 2016], maximum values of seismic activity in the range of magnitudes 2≤M≤4 also form a sequence of spatial cells in the form of seismic clusters from the east (Sakhalin – Sakh) to the west (the western boundary of the Baikal rift zone – BRZ ) (Fig. 1). One of the main characteristics of the seismic process is seismic activity migration given as sequential activation of seismogenic structures within the seismically active zones and on the global scale [Vikulin et al., 2012; Khain, Khalilov, 2008]. Direct observations show that crust deformation migrates from the Japan-Kuril-Kamchatka subduction zone towards the continent, and the estimated migration rates range from 10 to 140 km per year (e.g. [Ishii et al., 1978; Kasahara, 1979; Harada et al., 2003; Yoshioka et al., 2015]). In the Baikal and Amur regions (107–140°E), the fronts of deformation waves migrate at a rate of 5–20 km per year [Sherman, 2007, 2013]. Considering the order of magnitude, this rate is comparable to the rates of crust deformation migration from the Japan-Kuril-Kamchatka zone (10–100 km per year). Our studies show that the sequential activation of the seismic clusters in the northeastern segment of the Amur plate (Sakh – TanLu – Al-St) occurs at a rate of 1000 km per year [Trofimenko et al., 2015a] (Fig. 1). In the meridional tectonic structures, the shifting chains of maximum seismicity values are sequentially replaced by minimum values (i.e. inversion zones). Based on the spatial cycles with the phase shift of the maximum seismic activity values at the rate of 1000 km per year, it is possible to represent the dynamics of seismicity in the form of a process initiated by long-period stress waves/deformations. According to [Mogi, 1968; Kasahara, 1979; Malamud, Nikolaevskii, 1989; Saprygin et al., 1997; Harada et al., 2003; Bykov, 2005, 2014; Sherman, 2007, 2013, 2014; Milyukov et al., 2013], slow deformation waves of the global and regional scale are generated at the margins of lithospheric plates. Under this concept, the migration rate of seismic activity and the spatial extent of seismic cycles can be identified as the velocity and length of deformation waves. Using the data on seismicity of the most active region of the Baikal rift zone – the northwestern segment of the Amur plate, we have studied the periodic components of seismicity along the entire northern boundary of the Amur plate. An indirect evidence of the existence of deformation waves is the migration of anomalies of geophysical fields and its correlation with the migration of seismic activity. The space-time anomalies of the magnetic and gravity fields were studied in the South Yakutian geodynamic polygon [Trofimenko, 1990; Trofimenko, Grib, 2003, 2016], and the indicators of deformation waves were revealed in the seismic regime and the geophysical fields at the northern margin of the Amur plate. The sequential manifestation of anomalies in the magnetic and gravity fields is associated with the activation of latitudinal tectonic structures. Our estimations show that the geophysical anomalies migrate at different rates, from 100 to 1000 km per year. Based on the results obtained in our study and their comparison with other available data, the dynamics of seismicity along the northern margin of the Amur plate is identified as a wave process.

Assessing current temporal and space-time anomalies of disease incidence.

Approaches used to early and accurately characterize epidemiologic patterns of disease incidence in a temporal and spatial series are becoming increasingly important. Cluster tests are generally designed for retrospective detection of epidemiologic anomalies in a temporal or space-time series. Timely identification of anomalies of disease or poisoning incidence during ongoing surveillance or an outbreak requires the use of sensitive statistical methods that recognize an incidence pattern at the time of occurrence. This report describes 2 novel analytical methods that focus on detecting anomalies of incidence at the time of occurrence in a temporal and space-time series. The first method describes the paucity of incidence at the time of occurrence in an ongoing surveillance and is designed to evaluate whether a decline in incidence occurs on the single current day or during the most recent few days. The second method provides an overall assessment of current clustering or paucity of incidence in a space-time series, allowing for several space regions. We illustrate the application of these methods using a subsample of a temporal series of data on the largest dengue outbreak in Taiwan in 2015 since World War II and demonstrate that they are useful to efficiently monitor incoming data for current clustering and paucity of incidence in a temporal and space-time series. In light of the recent global emergence and resurgence of Zika, dengue, and chikungunya infection, these approaching for detecting current anomalies of incidence in the ongoing surveillance of disease are particularly desired and needed.

On the potential of an RST-based analysis of the MODIS-derived chl-a product over Condor seamount and surrounding areas (Azores, NE Atlantic)

Oceanographic cruises have been conducted on the Condor seamount (SW Faial Island, Azores archipelago, NE Atlantic) since 2009 to collect in situ data and understand potential seamount effects on local biodiversity. Satellite data have been concurrently collected to infer the space-time upper-ocean optical property variability and the associated physical processes. The main limitation of this analysis is the persistent and significant cloud coverage above the region that, especially in some seasons, can significantly hinder satellite data availability. This study was meant to test the robust satellite technique (RST) over the Condor seamount, assess its capability to estimate multiyear trends and identify space-time anomalies. To this aim, 11-year MODIS/AQUA level 2-derived chlorophyll-a (chl-a) data were used. Results achieved for October 2010 show, within a large-scale analysis, the presence of well-defined areas of near-surface chl-a anomalies, highlighting the occurrence of a trapping effect due to flow-topography interaction processes. Regarding the Condor area, the chl-a anomalies detected along the eastern side of the seamount were linked to a strong vertical mixing that provided sufficient inorganic nutrients requested for productivity. The achieved results, whose accuracy was also tested through a comparison with in situ data, are consistent with those independently obtained by other authors who described the phytoplankton variability around the Condor seamount. This study shows the high potential of the RST approach to assess the chl-a variability in the space-time domain in oligotrophic regions such as the Azores, allowing the identification of the most important areas to be preserved and/or managed.

Detection of dynamic objects on the basis of space-time anomalies in video sequences

Codes and algorithms are developed for detecting small-size dynamic thermal objects on the basis of searching for space-time anomalies in the observation field formed by a sequence of infrared images. Results of studying the method effectiveness, based on data obtained under conditions of a real background-target environment, are presented.

Robust satellite techniques for remote sensing of seismically active areas

Several satellite techniques have been recently proposed to remotely map seismically active zones and to monitor geophysical phenomena possibly associated with earthquakes. Even if questionable in terms of their effective applicability, all these techniques highlight as the major problem, still to be overcome, the high number of natural factors (independent of any seismic activity) whose variable contributions to the investigated signal can be so high as to completely mask (or simulate) the space-time anomaly possibly associated to the seismic event under study. A robust approach (RAT) has recently been proposed (and successfully applied in the field of the monitoring of the major environmental risks) which, better than other methods, seems suitable for recognising space-time anomalies in the satellite observational field also in the presence of highly variable contributions from atmospheric (transmittance), surface (emissivity and morphology) and observational (time/season, but also solar and satellite zenithal angles) conditions.This work presents the first preliminary results, based on several years of NOAA/AVHRR observations, regarding its extension to satellite monitoring of thermal anomalies possibly associated to seismically active areas of Southern Italy. The main merits of this approach are its robustness against the possibility of false events detection (specially important for this kind of applications) as well as its intrinsic exportability not only to different geographic areas but also to different satellite instrumental packages.

Robust satellite techniques for volcanicand seismic hazards monitoring

Several satellite techniques have been proposed to monitor events related to seismic and volcanic activity. A selfadaptive approach (RAT, Robust AVHRR Techniques) has recently been proposed which seems able to recognise space-time anomalies, differently related to such events, also in the presence of highly variable contributions from atmospheric (transmittance), surface (emissivity and morphology) and observational (time/season, but also solar and satellite zenithal angles) conditions. On the basis of NOAA-AVHRR data, the RAT aprroach has already been applied to Mount Etna volcanic ash cloud monitoring in daytime, and to seismic area monitoring in Southern Italy. This paper presents the theoretical basis for the extension of RAT approach also to nighttime volcanic ash cloud detection, together with its possible implementation to lava flow monitoring. One example of successful forecasting (few days before) of a new lava vent opening during the Mount Etna eruption of July 2001 will be discussed in some detail. Progress on the use of the same approach on seismically active area monitoring will be discussed by comparison with previous results achieved on the Irpinia-Basilicata earthquake (MS = 6.9), which occurred on November 23rd 1980 in Southern Italy.

Statistical Methods for Anomalous Discrete Time Series Based on Minimum Cell Count

Temporal incidence patterns of point epidemics often contain periods of unusually low or high frequencies. Identifying variations in incidence frequencies, which may be caused by changes in exposure to infectious or environmental agents, may provide important insights into the pathogenesis or etiology of a disease. We propose and formulate new statistical tests for temporal and space-time anomalies that are based on the minimum frequency in a unit of time and that are meaningful for the characteristic incidence patterns of the cases studied. Among the most widely applied methods are the Ederer-Myers-Mantel test, the Maxima test, and the scan test, which are all sensitive to the maximum frequency within a short period of time. We elucidate the importance and utility of our new tests and the existing tests and suggest a systematic statistical analysis of reported disease anomalies using these tests combined. Data on a temporal series of adolescent suicide from the US National Center for Health Statistics were analyzed using these methods.

Aspects of stability and phenomenology in type IIA orientifolds with intersecting D6‐branes

AbstractIntersecting branes have been the subject of an elaborate string model building for several years. After a general introduction into string theory, this work introduces in detail the toroidal and \documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}$\mathbb{Z}_N$\end{document}‐orientifolds. The picture involving D9‐branes with B‐fluxes is shortly reviewed, but the main discussion employs the T‐dual picture of intersecting D6‐branes. The derivation of the R‐R and NS‐NS tadpole cancellation conditions in the conformal field theory is shown in great detail. Various aspects of the open and closed chiral and non‐chiral massless spectrum are discussed, involving spacetime anomalies and the generalized Green‐Schwarz mechanism. An introduction into possible gauge breaking mechanisms is given, too. Afterwards, both 𝒩 = 1 supersymmetric and non‐supersymmetric approaches to low energy model building are treated. Firstly, the problem of complex structure instabilities in toroidal ΩR‐orientifolds is approached by a \documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}$\mathbb{Z}_3$\end{document}‐orbifolded model. In particular, a stable non‐supersymmetric standard‐like model with three fermion generations is discussed. This model features the standard model gauge groups at the same time as having a massless hypercharge, but possessing an additional global B‐L symmetry. The electroweak Higgs mechanism and the Yukawa couplings are not realized in the usual way. It is shown that this model descends naturally from a flipped SU(5) GUT model, where the string scale has to be at least of the order of the GUT scale. Secondly, supersymmetric models on the \documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}$\mathbb{Z}_4$\end{document}‐orbifold are discussed, involving exceptional 3‐cycles and the explicit construction of fractional D‐branes. A three generation Pati‐Salam model is constructed as a particular example, where several brane recombination mechanisms are used, yielding non‐flat and non‐factorizable branes. This model even can be broken down to a MSSM‐like model with a massless hypercharge. Finally, the possibility that unstable closed and open string moduli could have played the role of the inflaton in the evolution of the universe is being explored. In the closed string sector, the important slow‐rolling requirement can only be fulfilled for very specific cases, where some moduli are frozen and a special choice of coordinates is taken. In the open string sector, inflation does not seem to be possible at all.

Absence of world-sheet and spacetime anomalies in the semi-covariantly quantized heterotic string

The anomalies of the heterotic string in the semi-light-cone gauge can be removed by adding suitable local order ℏ terms to the local Weyl and spacetime (rigid) Lorentz transformation rules. The resulting quantum transformation rules exactly satisfy the spacetime Lorentz algebra. This removes the doubt, expressed in the literature, concerning the consistency of the heterotic string at the quantum level.

Superstring anomalies in the semi-light-cone gauge

We compute the Einstein, Lorentz and Weyl worldsheet anomalies and the super-Poincaré space-time anomalies of the heterotic superstring, using path-integrals and the gauge Γ + Θ=0 to fix the local fermionic κ-symmetry. The regulators for the various jacobians are all obtained from a recent general method of constructing consistent regulators. We do not use a special gauge for the metric. A general lemma for anomalies of algebraic and non-algebraic symmetries is obtained. Our results show that only for a certain class of metrics do all worldsheet and space-time anomalies cancel simultaneously after adding a suitable but complicated set of counterterms.

Consistency of open superstring theories

The infinities and the anomalies in the G≠SO(32) open superstring arise from the same limit of the one-loop Riemann surfaces. The dilaton tadpole infinity is removable by an appropriate choice of background, as in the work of Fischler and Susskind. However, we find that the anomalies arise from the tadpole of an unphysical field, and cannot be removed by any choice of background. Thus, the spacetime anomalies are due to a world-sheet superconformal anomaly of topological origin. We also give a general discussion of the relation between anomalies and surface terms in moduli space, and point out several new applications.