Depth Of Foci Research Articles

Five decades of catastrophe theory research: Geographical atlas, knowledge structure and historical roots

Catastrophe theory research has recently witnessed a distinct proliferation. In this article we apply bibliometric network techniques to examine the conceptual/intellectual structure of this domain based on 1498 Scopus documents written by 2745 authors representing 69 nations and spanning almost five decades (1975–2020). The study aims to explore the catastrophe theory research impactful authors, influential journals, collaboration networks and emerging trends. Additionally, keyword co-occurrence techniques are employed to scrutinize major schools of thought. Results show that the most impactful journals publishing catastrophe theory research are Behavioral Science, Physical Review D, Ecological Modeling, Journal of Physical Chemistry A and the Journal of Theoretical Biology. Results also show that the author collaboration network in catastrophe theory research is sparse. Furthermore, results related to collaborative networks among institutions and countries reveal a global “North-South” schism between developed and developing nations. The multiple correspondence analysis (MCA) applied to obtain the catastrophe theory research conceptual map reflects the depth and breadth of the research's foci. Finally, the reference publication year spectroscopy (RPYS) was used to detect the “citation classics” forming the historical roots of catastrophe theory research. Our analysis has far-reaching implications for aspiring researchers interested in catastrophe theory research as we retrospectively trace the evolution in research output over the last five decades, establish linkages between the authors and articles, and reveal trending topics/hotspots within the broad theme of catastrophe theory research.

Three decades of interactive learning environments: a retrospective bibliometric network analysis

ABSTRACT Interactive Learning Environments (ILE) is a leading international journal in the design and use of interactive learning environments. In this study we conduct a comprehensive bibliometric analysis spanning three decades to objectively examine the journal's impactful authors, citation patterns, collaboration networks and emerging trends. Additionally, keyword co-occurrence techniques are employed to scrutinize the journal's knowledge/intellectual structure. We use the Scopus database to analyze 995 articles published in the journal by 2298 authors representing 65 nations from 1990 to 2020. Results show that the most productive authors are Gwo Jen Hwang (57 articles), Timothy Teo (18 articles) and Yeuh Min Huang (11 articles). Results also show that the author collaboration network is sparse. Furthermore, results related to collaborative networks between institutions and countries reveal a global “North-South” schism between developed and developing nations. Finally, the multiple correspondence analysis (MCA) applied to obtain the ILE conceptual map reflects the depth and breadth of the journal's foci. Our analysis has far-reaching implications for aspiring researchers interested in the design and use of interactive learning environments research.

On the Electrophysiology and Mapping of Intramural Arrhythmic Focus.

Conventional mapping of focal ventricular arrhythmias relies on unipolar electrogram characteristics and early local activation times. Deep intramural foci are common and associated with high recurrence rates following catheter-based radiofrequency ablation. We assessed the accuracy of unipolar morphological patterns and mapping surface indices to predict the site and depth of ventricular arrhythmogenic focal sources. An experimental beating-heart model used Langendorff-perfused, healthy swine hearts. A custom 56-pole electrode array catheter was positioned on the left ventricle. A plunge needle was placed perpendicular in the center of the grid to simulate arrhythmic foci at variable depths. Unipolar electrograms and local activation times were generated. Simulation models from 2 human hearts were also included with grids positioned simultaneously on the endocardium-epicardium from multiple left ventricular, septal, and outflow tract sites. A unipolar Q or QS complex lacks specificity for superficial arrhythmic foci, as this morphology pattern occupies a large surface area and is the predominant pattern as intramural depth increases without developing a R component. There is progressive displacement from the arrhythmic focus to the surface exit as intramural focus depth increases. A shorter total activation time over the overlying electrode array, larger surface area within initial 20 ms activation, and a dual surface breakout pattern all indicate a deep focus. Displacement from the focal intramural origin to the exit site on the mapping surface could lead to erroneous lesion delivery strategies. Traditional unipolar electrogram features lack specificity to predict the intramural arrhythmic source; however, novel endocardial-epicardial mapping surface indices can be used to determine the depth of arrhythmic foci.

Study of the corrosion resistance of aluminum alloy AMg6 and steel 12Kh18N10T in conditions of loading under the impact of environmental factors

Stress corrosion cracking is one of the most dangerous types of corrosion damage in metallic materials. We present the results of studying the impact of environmental factors on the susceptibility of AMg6 aluminum alloy and 12Kh18N10T stainless steel to stress corrosion cracking under four-point bending. Tests of loaded samples were carried out in laboratory and field conditions of the moderately warm climate of the coastal zone over a period of six months. The samples were examined daily with fixation of the time to their destruction and upon completion of the tests the appearance of the samples and the depth of intergranular corrosion on microsections were assessed. A 3D relief was constructed using macro photography of the surface with the determination of the depth of corrosion foci. We also carried out a comparative analysis of the frequency of stress-induced destruction of steel samples of various grades both in atmospheric and laboratory conditions. It is shown that in atmospheric conditions characterized by the presence of dust particles acting as concentrators for the formation of corrosion foci, the aggressiveness of the corrosive effect of the environment increases, whereas the general corrosion resistance of materials decreases. The most pronounced effect of the environment was recorded in AMg6 alloy samples when exposed under a ventilated canopy in conditions of periodic spraying of seawater aerosols. The depth of surface corrosion damage was up to 0.1 mm. When the test samples were exposed under other conditions (salt fog chamber and louvered storage) the corrosion damage was absent. The results obtained can be used to predict the corrosion resistance of the products made of AMG6 alloy and 12Kh18N10T steel when operated in conditions of loading under the impact of environmental factors.

Adenomyosis and in vitro fertilization impacts - A literature review.

Adenomyosis is a gynecological condition, which is characterized by stromal and glandular endometrial tissue infiltration inti the myometrium, resulting in an increase of uterine volume. The etiology of adenomyosis is presently unknown, but some theories assist us in understanding its pathogenesis and natural history. Clinical manifestations are increased menstrual flow and dysmenorrhea, abnormal uterine bleeding, chronic pelvic pain, and dyspareunia. The signs and symptoms suggestive of adenomyosis are complemented by diagnostic methods such as transvaginal ultrasound (TVUS), ideally with intestinal preparation, magnetic resonance imaging (MRI) and surgery; although currently, there are no precise criteria for the classification of findings on imaging studies. The clinical and surgical therapeutic approach must be individualized, taking into account the patient’s characteristics, for instance, age, parity, depth and number of adenomyotic foci, uterine volume and, mainly, clinical manifestations. A causal relation between adenomyosis and infertility has been repeatedly suggested, mostly due to the anatomo-physiopathological conditions originated by the adenomyosis on the female genital tract; however, definitive conclusions are still lacking. This pathology is found in approximately 25% of infertile women, especially those who have had recurrent pregnancy loss (RPL), recurrent implantation failure, older women seeking In Vitro fertilization (IVF) treatment, and those with concomitant endometriosis. To determine whether adenomyosis per se affects fertility, several researchers have focused on women who are affected by the condition and underwent IVF/intracytoplasmic sperm injection (ICSI); for this model provides more accurate data about the influence of adenomyosis on embryo implantation. Therefore, our objective was to analyze, through a systematic literature review, the effect of uterine adenomyosis on the probability of pregnancy by IVF / ICSI, as well as trying to point out the main difficulties and gaps to establish a standard protocol for the management of these patients, since most of the patients with adenomyosis have other associated gynecological pathologies, mostly endometriosis; in addition to the heterogeneity of the studies still remaining as an obstacle to precise conclusions.

Relationship Between Depth of Seismicity and Heat Flow: The Case of the Gargano Area (Italy)

We consider a thermo-rheological model made of a viscoelastic half-space with Maxwell rheology and temperature-dependent viscosity. The half-space is made of layers with different values of density, thermal conductivity, activation energy and heat productivity. The model relates the surface heat flow to the depth of the brittle-ductile transition and the thickness of the seismogenic layer. The model is applied to the Gargano area (Italy) which is subject to a frequent low-magnitude seismic activity, although it lies out of the Apennine axis, which is the main Italian seismogenic area. The seismic activity in the Gargano area and surroundings occurs at depths that are systematically different in the north-eastern zone with respect to the south-western zone. In correspondence with the change in depth of earthquake foci, we observe a change in the value of surface heat flow. Starting from these observations and from the knowledge of the lithospheric structure, we propose two different geotherms for the two zones. Assuming a constant strain rate, the shear stress is computed as a function of depth and the thickness of the seismogenic layer in the two zones is inferred. The comparison of the results of the thermo-rheological model with the seismological observation is good.

F123. Ultra-high-density scalp EEG outperforms localized invasive ECoG grids in inferring depth of seizure foci

Introduction During pre-surgical evaluation for medically intractable epilepsy, intracranial electrocorticography (ECoG) is often used to locate seizure foci. However, ECoG grids usually have small spatial coverage because large coverage requires large craniotomies. This may pose difficulties in inferring the depth of the focus, which is important because foci can lie deep inside the brain, e.g. in insular, mesial or basal regions, or within a sulcus. Our team recently demonstrated theoretically [Grover & Venkatesh, Proc. IEEE, ‘17] and experimentally[Robinson et al., Scientific Reports ‘17] that ultra-high-density (UHD) scalp EEG (with sub-centimeter electrode spacing) can recover high spatial resolution information of brain activity. Here, we ask whether UHD-EEG with full scalp coverage can outperform spatially localized ECoG grids in inferring the depth of seizure foci. Methods In our simulation study, ECoG and UHD-EEG electrodes were placed on a template-head MRI. Brainstorm and OpenMEEG were used to generate EEG and ECoG forward models using the Boundary Element Method for the ICBM-152 Brain template with 15,765 dipoles. For 20-electrode ECoG simulations, 8 different locations were considered (over frontal, fronto-parietal, posterior-temporal and occipital regions on left and right hemispheres), with sources at different locations in each case. For 40-electrode ECoG simulations, two adjacent 20-electrode ECoG grids were considered, again for varying source locations. A single radially oriented dipole was manually activated at different depths from each of the 8 locations on the cortex, beneath the 20-electrode ECoG grid. For EEG, 128, 256 and 1378 electrodes (the last being a theoretical UHD EEG system) with whole scalp coverage were considered. Noiseless ECoG and EEG recordings were simulated, and source localization was performed to estimate the source location using the L2-regularized MNE algorithm. Results of source localization were then compared using two standard metrics: the distance of the center of the reconstruction from the true source (bias) and the diffusive extent of the reconstruction (width of Point Spread Function, PSF). Results The reconstruction-bias using UHD-EEG is consistently about 2 cm less than any ECoG reconstruction. PSF widths of deeper sources are observed to be slightly larger for ultra-high-density EEG than other modalities. Nevertheless, visual inference of depth is more accurate using reconstructions of ultra-high-density EEG. Conclusion UHD-EEG can complement other modalities used during pre-surgical evaluation for epilepsy, before and after intracranial electrode implantation, particularly for inferring the presence of a deep seizure focus. ECoG recordings strongly bias reconstructions towards the cortical surface. Future work will similarly compare stereo-EEG and UHD-EEG, for inferring depth of seizure foci, and evaluate how UHD-EEG can inform stereo-EEG electrode placement.

The morphology of unipolar potentials predicts the depth of activation foci

BackgroundThe depth of an arrhythmic focus is a major determinant of ablation procedural outcome. This study examined the relationship between the morphology of unipolar potentials and the depth and horizontal distance to activation foci. MethodsUnipolar left ventricular epicardial mapping was performed in 7 open-chest dogs, using silicon sheets with 12 unipolar electrodes 1mm apart, during bipolar pacing from an octopolar plunge electrode with 1-mm interelectrode spacing. The morphology of the unipolar electrograms was classified as QS, rS, qrS, qRS, rsr’S, or rsR’S. ResultsA QS complex was recorded immediately above a subepicardial or mid-myocardial pacing site. An rS complex was recorded away from a subepicardial pacing site. A positive wave originating from a down sloping deflection (R-in-QR) such as r wave in qrS, R wave in qRS, r′ wave in rsr’S or R′ wave in rsR’S complexes was observed when the recording was above a deep myocardial pacing site or away from a mid-myocardial pacing site. The amplitude of negative wave immediately before R-in-QR (Q-in-QR) was inversely correlated with the horizontal (R=−0.40; P<0.0001) and linear (R=−0.22; P=0.0006) distance to the pacing site, and the amplitude of R-in-QR was positively correlated with the horizontal (R=0.25; P=0.0001) and linear (R=0.29; P<0.0001) distance to the pacing site. The amplitude of the initial r wave was not correlated with the depth or horizontal and linear distance to the pacing site. ConclusionThe morphology of unipolar electrograms predicted the horizontal distance and the depth of nearby foci of activation.

Розрахунок та аналіз азимутальних коефіцієнтів qi та уточнення швидкісної моделі Закарпатського сейсмоактивного регіону

The aim of this paper is to clarify the velocity model of the Transcarpathian seismic region. The model will further be implemented in neural-network modelling to calculate and verify the depth and distribution of earthquake foci. There has been carried out an analysis of seismic wave propagation in different directions across the Transcarpathian seismic region. Being an important parameter indicative of the direction of wave propagation in a natural medium, the azimuthal coefficient q³ has proved to be efficient in developing a training neural network set. Two methods of selecting sectors have been shown, based either on the location of a seismic station or a seismic event area. We have calculated average values of the azimuthal coefficient q³ for sectors with close values of q³ for one-, two- and three-layered media according to the depth of earthquake foci in each of the three layers. With three-layered media covering earthquake foci depths of 8,000-9,000 m, the calculations accurately reflect local seismic events in the Carpathians. An average layer thickness h and an average layer velocity v were calculated separately for each E-S pair (epicenter - seismic station). Conventional combining of layers was used as a method of calculating the third layer azimuth coefficient q³. The calculations were made for direct P-waves (similar calculations can be made for S-waves). We have suggested an interpretation of the obtained results and their practical implications. It has been demonstrated how the azimuthal coefficient can be used in analysing the parameters of media.

Thirty years of precise gravity measurements at Mt. Vesuvius: an approach to detect underground mass movements

&lt;p&gt;Since 1982, high precision gravity measurements have been routinely carried out on Mt. Vesuvius. The gravity network consists of selected sites most of them coinciding with, or very close to, leveling benchmarks to remove the effect of the elevation changes from gravity variations. The reference station is located in Napoli, outside the volcanic area. Since 1986, absolute gravity measurements have been periodically made on a station on Mt. Vesuvius, close to a permanent gravity station established in 1987, and at the reference in Napoli. The results of the gravity measurements since 1982 are presented and discussed. Moderate gravity changes on short-time were generally observed. On long-term significant gravity changes occurred and the overall fields displayed well defined patterns. Several periods of evolution may be recognized. Gravity changes revealed by the relative surveys have been confirmed by repeated absolute measurements, which also confirmed the long-term stability of the reference site. The gravity changes over the recognized periods appear correlated with the seismic crises and with changes of the tidal parameters obtained by continuous measurements. The absence of significant ground deformation implies masses redistribution, essentially density changes without significant volume changes, such as fluids migration at the depth of the seismic foci, i.e. at a few kilometers. The fluid migration may occur through pre-existing geological structures, as also suggested by hydrological studies, and/or through new fractures generated by seismic activity. This interpretation is supported by the analyses of the spatial gravity changes overlapping the most significant and recent seismic crises.&lt;/p&gt;

Localization and propagation analysis of ictal source rhythm by electrocorticography

The purpose of this study was to develop a novel approach for objectively estimating the locations of ictal onset zones by electrocorticography (ECoG). Conventional ECoG analyses have been performed using a 2-D space comprised of intracranial electrodes. Thus, despite the fact that ECoG data have much higher signal-to-noise ratios than electroencephalographic data, ECoG inherently requires a priori information to locate the electrodes, and thus, it is difficult to estimate the depth of epileptogenic foci using this technique. Accordingly, the authors considered that a 3-D approach is needed to determine the presence of an epileptogenic focus in the complex structure of the cortex. However, no source localization procedure has been devised to determine the location of a primary ictal source using ECoG. The authors utilized a spatiotemporal source localization technique using the first principal vectors. A directed transfer function was then employed for the time series of potential ictal sources to compute their causal inter-relationships, from which the primary sources responsible for ictal onset could be localized. Monte-Carlo simulation studies were performed to validate the feasibility and reliability of the proposed ECoG source localization technique, and the obtained results demonstrated that the mean of localization errors with a signal to white Gaussian noise ratio of 5dB did not exceed 5mm, even when the source was located ∼20mm away from the nearest electrode. This validated ictal source localization approach was applied to a number of ictal ECoG data sets from six successfully operated epilepsy patients. The resultant 3-D ictal source locations were found to coincide with surgical resection areas and with traditional 2-D electrode-based source estimates. The authors believe that this proposed ECoG-based ictal source localization method will be found useful, especially when ictal sources are located in a deep sulcus or beyond recording planes.

Can noncontact mapping distinguish between endo- and epicardial foci?

Noncontact mapping has been demonstrated to facilitate RF ablation of ventricular arrhythmias, but the reproducibility in the localization of endocardial exit sites during focal ventricular tachycardia ("VT") originating from defined myocardial layers has not been systematically studied. Furthermore, it remains unclear whether noncontact mapping can distinguish between endo- and epicardial foci. In six dogs, constant pacing was applied through octopolar needle electrodes in the left ventricle to mimic VT of subendocardial, midmyocardial (mid1; mid2) or subepicardial origin. Using noncontact mapping, the site of origin was determined for each of 50 consecutive beats of all "VTs" and the variation between respective exit sites was measured. Exit sites were reconstructed for 50 consecutive beats of each "VT" and the time span between site of origin and exit site was measured as a parameter of intramural conduction. While subendocardial and midmyocardial (mid1, mid2) foci were pinpointed with a variation of <or=2 mm, a variation of 4 mm was encountered for subepicardial foci. A gradual increase in intramural conduction was evident from endocardial towards epicardial foci, with significant differences between subendocardial (4.8 +/- 0.9 ms), midmyocardial (mid1 = 11.1 +/- 4.6 ms; mid2 = 11.8 +/- 3.5 ms) and subepicardial (16.8 +/- 3.6 ms) foci (P < 0.005). Systematic differences in the morphology of virtual waveforms depending on the site of origin could not be detected. Except for subepicardial foci, noncontact mapping localized focal activity in the LV with high reproducibility. In contrast to morphological parameters, the determination of intramural conduction provides a fair estimate of the depth of foci and is proposed as a novel parameter to identify a subepicardial origin.

Strange attractor in earthquake swarms near Valsad (Gujarat), India

Valsad district in south Gujarat near the western coast of the peninsular India experienced earthquake swarms since early February 1986. Seismic monitoring through a network of micro earthquake seismographs showed a well concentrated seismic activity over an area of 7 × 10 km2 with the depth of foci extending from 1 to 15 km. A total number of 21,830 earthquakes were recorded during March 1986 to June 1988. The daily frequency of earthquakes for this period was utilized to examine deterministic chaos through evaluation of dimension of strange attractor and Lyapunov exponent. The low dimension of 2.1 for the strange attractor and positive value of the largest Lyapunov exponent suggest chaotic dynamics in Valsad earthquake swarms with at least 3 parameters for earthquake predictability. The results indicate differences in the characteristics of deterministic chaos in intraplate and interplate regions of India.

Thermal model of the Vesuvius magma chamber

A thermal modeling of the Vesuvius is presented, based on its magmatic and volcanic history. A 2D numerical scheme has been developed to evaluate the heat transfer inside and around a magma body, the latent heat of crystallization and the inputs of magma from the asthenosphere to a crustal reservoir. Assuming a ratio &gt;1 between velocities of magma ascending in the conduit and magma laterally displaced in the reservoir, the results indicate that, after 40 ka, the reservoir is vertically thermally zoned. As a consequence it hosts magma batches that can individually differentiate, mix and be contaminated by the crust, and produce the spectrum of isotopic compositions of the Vesuvian products. The thermal model reproduces the geothermal gradient and the brittle‐ductile transition (250–300°C) at 6 km of depth (the maximum depth of earthquake foci) only after 0.5–1 Ma, implying a long lived magma chamber below the volcano.

Adenomyosis: symptoms, histology, and pregnancy terminations

Objective: To correlate symptoms of uterine adenomyosis with histopathologic features. Methods: One hundred eleven specimens of uteri and cervices that weighed under 280 g were reevaluated. When adenomyosis was identified, assessment included depth of adenomyotic foci, graded as deep (above 80%), intermediate (40–80%), and superficial (under 40%), and number of adenomyotic foci. Clinical data were collected from patient records. Results: Specimens were categorized in four groups, 17 with adenomyosis alone, 19 with adenomyosis with leiomyomas, 39 with leiomyomas alone, and 36 with neither. Among women with adenomyosis alone, 58.8% had pregnancy terminations and 47.4% of women with adenomyosis and leiomyomas had terminations, compared with 20.5% of women with leiomyomas alone ( P < .01) and 22.2% in those with neither ( P < .01). The number of foci correlated significantly with depth within the myometrium in specimens with adenomyosis alone ( r = .46, P = .05) or combined with leiomyomas ( r = .66, P < .001). The median number of foci associated with dysmenorrhea was 10 compared with 4.5 without it ( P < .003); in menorrhagia the respective median numbers were 7 and 7 ( P = .25). Menorrhagia and dysmenorrhea presented in 36.8% and 77.8% of deep, compared with 13.3% ( P < .001) and 12.5% ( P < .001) of intermediate depths, respectively. Superficial depth was not associated with menorrhagia or dysmenorrhea. Conclusion: Pregnancy termination might affect the pathogenesis of adenomyosis. The number of foci and their myometrial depths correlated to each other and to dysmenorrhea, but only myometrial depth correlated to menorrhagia.

A structural model for active extension in Central Italy

This work presents a structural model for earthquake faulting in the Umbria-Marche Apennines (Central Italy). The model is derived by an integrated analysis of geological, geophysical and seismological data. At regional scale, the distribution and character of the seismicity appear to be mainly controlled by a low-angle east-dipping normal fault (Altotiberina fault, AF). The latter is the lower boundary of an active, continuously deforming hangingwall block moving toward NE. Moderate magnitude earthquakes (4 < M < 6), such as the Norcia 1979 ( M = 5.9), the Gubbio 1984 ( M = 5.2) and the Colfiorito 1997 ( M max = 5.9), occur within the active hangingwall block and are related to the activity of major west-dipping normal faults detaching on the AF. The geometry of the deep seismogenic structures is listric (as in the case of Colfiorito) or more complex, because of local reactivation of pre-existing low-angle thrust (e.g. Gubbio) or high-angle strike-slip faults (e.g. Norcia). For all the analysed earthquakes the rupture nucleation is located at the base of the aftershock volumes, near the line of intersection between the SW-dipping normal faults and the east-dipping AF basal detachment. The progressive increase in depth of the earthquake foci from the north–west (e.g. Gubbio, 6–7 km) to the south–east (e.g. Norcia, 11–12 km) appears to be related to the eastward deepening of the basal detachment. These seismotectonic features are relevant for determining the seismogenic potential of the Apennine active faults, which depends not only on the length of the faults, but also on the depth of the detachment zone as well.

Q in the inner core

Short-period vertical seismograms from ten earthquakes and one nuclear explosion in the distance range of 140–170 degrees are examined for a study of the anelastic properties of the inner core. The depth of the earthquake foci varies between 116 and 625 km. The phases of interest are PKP(BC branch) and PKIKP with bottoming depths in the upper few hundred kilometers of the inner core. The data consist of high-quality digital data at sampling rates 2040 samples per second selected after an extensive search of the 1985–1986 GDSN event tapes for short-period P waves with a high signal-to-noise ratio. The results are based primarily upon observations between distances of 147° and 154°. Useful information regarding the attenuation characteristics of the region below the inner core boundary (ICB) can be obtained from the observed relative amplitude and frequency content of the PKIKP and PKP(BC) phases. We have used Fourier spectral ratios of PKIKP-PKP(BC) for the estimation of the attenuation along the inner core segment of the ray path. Because of the limited frequency band of the data, it is difficult to resolve any frequency dependence for Q. Within the depth range of 150–300 km below the inner core boundary, the data yield a maximum likelihood estimate of 175 for the mean estimate of Qα, with no clear indication of depth dependence.

Earthquake swarm activity in south Gujarat

South Gujarat, a part of western coast of Indian Peninsula started experiencing earth tremors of mild intensity since early February 1986. The shocks were widely felt with rumbling sound in these areas. More than 23000 micro earthquakes have since been recorded tilt December 1988, with a major event, ML=4.6 which occurred on.27 April.1986: In view of the location of multi-purpose projects like Ukai, Damanganga, .Jhuj, Kflia etc the monitoring this activity was Immediately started through a network of seven temporary- microearthquake recording stations. This was followed by various other studies such as geodetic, geomagnatic, radon gas monitoring and temperature measurements 9f hot springs. The Unai and Mola-Amba hot springs situated in this area have indicated the temperature of about 57oC and 37°C respectively against the normal atmospheric temperature of 33o C.&#x0D; &#x0D; The analysis by Hypo- 71 program on IBM computer of India Met. Dep., New Delhi, using a velocity model Koyna region has shown a well concentrated seismic activity over area of 7x 10 km2 and focal depth of 1-15 km. Clear migration of the activity has been observed. The activity which concentrated around Kella dam m early February-April 1986 migrated up to 18km to its south and back again to the religion around Kelia reservoir, by September 1987 with depth of foci progressively becoming shallower towards north .The 'b" value of 1.04 is higher than that of a few tectonic sequences of Peninsular India. The rate of decay of the activity was 0.52 which is rather slow compared to other sequences of the region. Hence, the reactivation of the existing fracturies/lineaments might be responsible or the recent activity. The geomagnetic studies in this area have corroborated tile existence of NW-SE to NNE-SSW trending conductive fractures. The earthquake activity during 1988 is quite low compared to earlier years.&#x0D;

Seismological study of the Kliuchevskoi flank eruption of 1983 (Kamchatka)

A flank eruption, called the Predskazanny eruption, occurred at an altitude of 2875 m on the east flank of the Kliuchevskoi volcano from March 8 to June 27, 1983. The eruption was largely effusive, with a constant chemical composition of the lavas (calc-alkaline aluminium basalts). Their volume is estimated at 0.11 km 3 . The seismic precursors of the Predskazanny eruption was concentrated beneath the new eruption center, first at depths of between 10 and 15 km (earthquake of February 28, K s = 8.3, M = 3.5) and then at depths between 5 km b.s.l. and 3 km a.s.l. (earthquake swarm of March 1–7). Volcanic tremor during the earthquake swarm of March 1–7 was absent. With the approach of an eruption, the depth of earthquake foci in the swarm decreased. An analysis of the seismicity implies that the magma was apparently ascending in the newly formed channel from a depth of at least 5 km. The feeding area of the Predskazanny eruption was apparently connected with the major magma channel of Kliuchevskoi at depths between 5 and 10 km, but not deeper than 15 km.

On the origin of recent vertical movements of the east Asiatic continent island systems

Recent slow vertical movements in Sakhalin, Japan and Kamchatka are mainly the continuation of modern movements that began in the Quaternary and older periods. In many cases positive and negative Recent vertical movements coincide spatially with uplifts and troughs, respectively. In some cases Recent movements are not stable in their sign, but are influenced by short-period “pulsations”; their total meanings for long periods of time according to their sign correlate on the whole with modern structure forms, being expressed as a relief. Spatial distribution and configuration and also conjunction of the uplift and trough areas, accompanied by variations of gravity anomalies, are strongly similar with the character of rapid vertical movements, connected with Recent volcanic activity and earthquakes. This circumstance allows us to assume their common origin also, connected with supply of sialic material into the Earth's crust. Cross-sectional sizes of uplifts and wave lengths of vertical movements allow us to determine the depth of foci (zones), where concentrations of supplied sialic material occur. For the most part of structures with sizes up to 60–70 km these foci are distributed at the depths of 10–15 km. There are also structures with longer wave length, which are connected with the formation of zones of partial melting near the Moho discontinuity or in the upper mantle. The occurrence of such foci is confirmed in many cases by the presence of zones of increased electric conductivity and decrease of the elastic wave velocities in the Earth's crust and upper mantle. The vertical movements mentioned above, which are apparently associated with a step-like rise of magmas of different composition, formation and evolution of partial melting zones on different levels, are supposed to be a widely spread phenomenon.