Journal of Volcanology and Seismology最新文献

{"title":"Observation and Research of Field Seismomagnetic Monitoring Experimental Areas in the Capital Region of China","authors":"Shupeng Su,&nbsp;Shuanggui Chen,&nbsp;Huiqin Zhao","doi":"10.1134/S0742046323700203","DOIUrl":"10.1134/S0742046323700203","url":null,"abstract":"<p>To explore an efficient approach refining seismomagnetic information through magnetic field survey technology, the author introduces the seismomagnetic monitoring system of the capital region in China. It includes field measurement techniques, data processing methods and application performance. The variation characteristics of the crustal magnetic field and seismomagnetic information in this area are systematically calculated and statistically analyzed based on the geomagnetic data products of the <i>X</i>, <i>Y</i>, and <i>Z</i> components. The results show that the mean amplitudes of <i>X</i>, <i>Y</i> and <i>Z</i> of the crustal magnetic field in the study area are 1.87, 1.90, and 1.39 nT, and the mean square deviations are 2.41, 2.48, and 1.94 nT, respectively. The epicenters of future large earthquakes will mostly lie near the “0” value line of crustal magnetic field variation with very low amplitude, which <i>X</i>, <i>Y</i> and <i>Z</i> elements are 18.7, 45.5 and 53.9% of the mean values in the survey area, respectively, and rise obviously after the earthquake. There is a high correlation between the location of the epicenter and the anomalous region of low spatial variation ratio of geomagnetic field secular variation.</p>","PeriodicalId":56112,"journal":{"name":"Journal of Volcanology and Seismology","volume":"17 4","pages":"338 - 351"},"PeriodicalIF":0.7,"publicationDate":"2023-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4853857","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Nizhny Birkachan Gold-Silver Epithermal Deposit, Omolon Massif, Northeast Russia: Geological Structure, Ore Mineralogy, and Age","authors":"A. N. Glukhov,&nbsp;V. V. Priymenko,&nbsp;A. B. Kotov,&nbsp;M. I. Fomina,&nbsp;E. B. Salnikova,&nbsp;T. I. Mikhalitsyna,&nbsp;G. O. Polzunenkov","doi":"10.1134/S0742046323700240","DOIUrl":"10.1134/S0742046323700240","url":null,"abstract":"<p>We have studied the geological structure, material composition of the ores, and the age of the Nizhny Birkachan volcanogenic gold–silver deposit discovered recently. The ore bodies consist of veins and vein-streak zones of adularia-carbonate-quartz composition; they lie in granodiorite porphyries with U‒Pb zircon age (ID-TIMS) equal to 335 ± 2 Ma. The ores are low sulfide, low silver (Au/Ag = 1–2), with pyrite dominating the ore minerals. The Ag minerals are tennantite, Ag sulfide, native gold and silver, and hessite. From an ore vein we obtained an adularia-based ⁴⁰Ar/³⁹Ar age equal to 169 ± 4 Ma, which reflects the rejuvenation of the isotopic argon system after the emplacement of a dike of unaltered Jurassic basites that cuts through the ore body. The Nizhny Birkachan deposit has a geological structure and ore composition that are very similar to those of other Au-Ag deposits at the Kedon volcano-plutonic belt such as Kubaka and Birkachan; it was also formed in the age span 290–335 Ma.</p>","PeriodicalId":56112,"journal":{"name":"Journal of Volcanology and Seismology","volume":"17 4","pages":"278 - 293"},"PeriodicalIF":0.7,"publicationDate":"2023-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4849007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Model for a New Peripheral Shallow Magma Chamber Beneath the Elbrus Volcanic Center","authors":"V. K. Milyukov,&nbsp;A. V. Myasnikov","doi":"10.1134/S0742046323700173","DOIUrl":"10.1134/S0742046323700173","url":null,"abstract":"<p>Crustal magmatic structures possess pronounced resonant properties, which enable these structures to generate secondary seismic waves at their eigen frequencies. Strain data acquired with the help of a 75-meter laser interferometer were used to identify resonant modes and to estimate the parameters of the magmatic structures beneath the Elbrus Volcanic Center. Such resonant modes are unique features for each magmatic feature, and determine the size and physico-mechanical properties of an identified internal structure. The present study contains an analysis of a local feature that has manifested itself as a compact area in the form of weak seismic pulses that have been recorded in the Elbrus area using small-aperture seismic instruments operated by the Geophysical Survey of the Russian Academy of Sciences (GS RAS) in 2011. The results of these studies based on seismic and strain observations, as well as on the results of microseismic sounding, have shown the existence of a new peripheral shallow magma chamber 2.5‒3 km across in size as part of the Elbrus Volcanic Center.</p>","PeriodicalId":56112,"journal":{"name":"Journal of Volcanology and Seismology","volume":"17 3","pages":"210 - 218"},"PeriodicalIF":0.7,"publicationDate":"2023-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4895868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The History of the Formation of Pliocene–Quaternary Valley Lava Rivers in the Northeast Part of the Javakheti Volcanic Highland, Lesser Caucasus","authors":"A. V. Parfenov,&nbsp;V. A. Lebedev,&nbsp;G. T. Vashakidze,&nbsp;A. I. Yakushev,&nbsp;B. D. Ediberidze","doi":"10.1134/S0742046323700070","DOIUrl":"10.1134/S0742046323700070","url":null,"abstract":"<p>This paper presents new results from geological-stratigraphic and isotope geochronological studies of young lavas in the northeast part of the Javakheti Highland, Lesser Caucasus, Georgia. We provide a first description of the Algeti complex-structured valley lava flow about 55 km in total length; no information on this feature is available in the geological literature. We show that young magmatism in the northeast part of the Javakheti region has been evolving in the time interval of 3.2–1.5 Ma B.P. Its earlier phases have produced the longest (up to 100 km) valley basaltic lava river of those known in the Lesser Caucasus (the Khrami flow) (3.19 ± 0.10 Ma B.P.). Subsequently (2.7–2.5 Ma B.P.), the eruptions continued to form extensive lava plateaus there (Tsalka, Gomareti, and other plateaus). In the Late Piacentian–Early Gelasian (2.7–2.0 Ma B.P.) the active vents in the northern Javakheti Range started to form the Algeti basaltoid valley flow, with this process lasting for ~1 Ma. The terminal phase of its formation (1.9–1.5 Ma B.P.) was probably related to eruptions of the volcanic cones in the area of Lake Tabatskuri. These data, along with the reconstruction of the history of young magmatism, enabled us to trace the main patterns in the generation of the present-day relief and the network of river valleys in the area of study in the Lesser Caucasus.</p>","PeriodicalId":56112,"journal":{"name":"Journal of Volcanology and Seismology","volume":"17 3","pages":"187 - 209"},"PeriodicalIF":0.7,"publicationDate":"2023-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4902562","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the Formation of Lava Flows and Lava Domes in Mafic-Intermediate Magmas (Mount Ungaran, Central Java, Indonesia)","authors":"Indranova Suhendro,&nbsp;Adrianto Shifa Al Aro,&nbsp;Muhammad Fikram Palembang,&nbsp;Ariqonitahanif Putri Rahim,&nbsp;Lusi Ratna Sari","doi":"10.1134/S0742046323700148","DOIUrl":"10.1134/S0742046323700148","url":null,"abstract":"<p>In this study, we combined the results of petrography [pheno-crystallinity (<span>({{phi }_{{PC}}})</span>)] and magma compositions (bulk and melt compositions) to calculate the magma viscosity (<span>({{{{mu }}}_{{{text{eff}}}}})</span>) of the lava flows and domes that erupted from Mount Ungaran, Central Java, Indonesia. The lava flows were characterized by slightly larger SiO₂ variations than those of lava domes, with a large overlap between each phase (46.7–57.8 and 53.2–59.8 wt % SiO₂, respectively). However, lava flows were typically less crystalline than the lava domes (average <span>({{phi }_{{PC}}})</span> of 33 and 40%, respectively). Because lava flows share an identical composition to lava domes and temperature is inversely proportional to SiO₂ content, it is inferred that magma composition and temperature did not play a substantial role in controlling magma viscosity. Instead, we found that pheno-crystallinity was the most important parameter. Specially, for a ±7% difference of pheno-crystallinity (at a given SiO₂), magma viscosity could differ by one order of magnitude, ultimately controlling lava morphology: high-viscosity magma (5.6–7.8 log Pa s) formed lava domes, whereas low-viscosity magma (4.6–6.6 log Pa s) produced lava flow. Moreover, we found that lava dome samples exhibited gentler phenocryst size distribution (CSD) slopes than lava flow samples (2.1–3.4 and 2.7–6.9, respectively). Because the CSD slope was inversely proportional to the magma residence time (CSD slope = –1/<i>Gt</i>), we suggest that lava dome formation, which requires a high magma viscosity, originates from a longer-lived and more crystalline magma, whereas lava flow with low magma viscosity originates from a young and less crystalline magma. Thus, in the case of mafic-to-intermediate magma, as in the present case, we think that the resultant lava morphology is strongly controlled by the abundance of phenocrysts and magma residence time.</p>","PeriodicalId":56112,"journal":{"name":"Journal of Volcanology and Seismology","volume":"17 3","pages":"228 - 245"},"PeriodicalIF":0.7,"publicationDate":"2023-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4898768","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Three-Dimensional Numerical Modeling of Lava Dynamics Using the Smoothed Particle Hydrodynamics Method","authors":"I. S. Starodubtsev,&nbsp;Y. V. Starodubtseva,&nbsp;I. A. Tsepelev,&nbsp;A. T. Ismail-Zadeh","doi":"10.1134/S0742046323700185","DOIUrl":"10.1134/S0742046323700185","url":null,"abstract":"<p>Lava domes and lava flows are major manifestations of effusive volcanic eruptions. Less viscous lava tends to flow long distances depending on the volcanic slope topography, the eruption rate, and the viscosity of the erupted magma. When magma is highly viscous, its eruption to the surface leads to the formation of lava domes and their growth. The meshless smoothed particle hydrodynamics (SPH) method is used in this paper to simulate lava dynamics. We describe the SPH method and present a numerical algorithm to compute lava dynamics models. The numerical method is verified by solving a model of cylindrical dam-break fluid flow, and the modelled results are compared to the analytical solution of the axisymmetric thin-layer viscous current problem. The SPH method is applied to study three models of lava advancement along the volcanic slope, when the lava viscosity is constant, depends on time and on the volume fraction of crystals in the lava. Simulation results show characteristic features of lava flows, such as lava channel and tube formation, and lava domes, such as the formation of a highly viscous carapace versus a less viscous dome core. Finally, the simulation results and their dependence on a particle size in the SPH method are discussed.</p>","PeriodicalId":56112,"journal":{"name":"Journal of Volcanology and Seismology","volume":"17 3","pages":"175 - 186"},"PeriodicalIF":0.7,"publicationDate":"2023-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4898560","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of the Seismicity Recorded before the May 22, 2021 Eruption of Nyiragongo Volcano, Democratic Republic of the Congo","authors":"A. T. Sadiki,&nbsp;A. M. Kyambikwa,&nbsp;D. B. Namogo,&nbsp;L. N. Diomi,&nbsp;O. M. Munguiko,&nbsp;G. M. Balezi,&nbsp;L. L. Sifa,&nbsp;S. M. Nzamu,&nbsp;N. Mashagiro,&nbsp;C. M. Balagizi,&nbsp;G. T. Mavonga","doi":"10.1134/S0742046323700136","DOIUrl":"10.1134/S0742046323700136","url":null,"abstract":"<p>We present an overview of the different seismic precursors of the Nyiragongo volcano eruption on May 22, 2021, as well as a statistical analysis of the seismic swarms recorded during the pre-eruptive period. The analysis of the seismic activity of Nyiragongo volcano during the pre-eruptive period shows that there was a particular seismicity composed of hybrid and/or volcano-tectonic type events that characterized the long-period seismic swarm recorded about a month before the May 2021 eruption. In February 2016, similar seismic activity was observed at Nyiragongo volcano, which led to the opening of a new vent within Nyiragongo's main crater on February 29, 2016, and which remained active until the May 2021 eruption. During the period from January 2016 to May 2021, the lava lake remained very active with significant fluctuation as evidenced by the Real Seismic Amplitude measurement at Rusayo and Kibati stations. The increase and stabilization of the lava lake to a higher level resulted in an increase and accumulation of stress on the flanks of the volcano since the lava lake had already reached a higher critical level. Whether in January 2016, November 2016 or April 2021, we show that this particular type of so-called hybrid seismic events recorded during a swarm at Nyiragongo volcano could lead to an eruption either inside the main crater (February 2016) or on the flanks in May 2021.</p>","PeriodicalId":56112,"journal":{"name":"Journal of Volcanology and Seismology","volume":"17 3","pages":"246 - 257"},"PeriodicalIF":0.7,"publicationDate":"2023-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4898746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Petrophysical Properties and Strength of Extrusive Rocks Discharged by Bezymianny Volcano, Kamchatka","authors":"V. M. Ladygin,&nbsp;O. A. Girina,&nbsp;Yu. V. Frolova","doi":"10.1134/S0742046323700197","DOIUrl":"10.1134/S0742046323700197","url":null,"abstract":"<p>This is the first petrophysical study of extrusive rocks (dacites to andesites) discharged by Bezymianny Volcano. We provide a comparative description of properties for extrusive rocks in accordance with identified age groups. We show the dynamics in the variation of extrusive rock properties in relation to their ages, with the result that the older a rock the higher are its density, strength, and elastic parameters. Rocks petrophysical features are compared between extrusive domes and lava flows. We argue for petrophysical properties to be applicable for deriving more accurate results for the genesis of rocks having similar petrophysical properties, in particular, rocks of extrusive and effusive origin.</p>","PeriodicalId":56112,"journal":{"name":"Journal of Volcanology and Seismology","volume":"17 3","pages":"159 - 174"},"PeriodicalIF":0.7,"publicationDate":"2023-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4896388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Retrospective Prediction of Location and Intensity for Two Large Crustal Earthquakes in Iran and India","authors":"V. N. Morozov,&nbsp;A. I. Manevich,&nbsp;V. N. Tatarinov","doi":"10.1134/S074204632370015X","DOIUrl":"10.1134/S074204632370015X","url":null,"abstract":"<p>This paper reports results of mathematical modeling applied to the stress and strain in epicentral zones before and after the large earthquakes that occurred on June 22, 2002 in the Qazvin Province, northwestern Iran (<i>M</i>_w = 6.4) and the Gujarat, India earthquake of January 26, 2001 (<i>M</i> = 6.9). The modeling relied on a method for calculating stress and strain in a blocky elastic isotropic heterogeneous medium disturbed by a set of faults that are due to an external tectonic stress field. The boundary conditions were specified based on geological and seismological data. It has been shown that the epicenters of large crustal earthquakes occur in zones of high stress concentration at the ends of tectonic faults. Rupture occurs when the relationship between acting tectonic stresses satisfies the requirement σ_<i>yy</i>/σ_<i>xx</i> &gt;3, thus connecting zones of high stress. The evolution of the aftershock process is controlled by the stress drop caused by a new rupture, while the resulting aftershock clusters are in spatial correlation with the stress drop zone. The new rupture propagates in the direction of dominant tectonic fault orientation in the region. We show a relationship to exist between rupture length and the possible retrospectively predicted location and magnitude of the earthquake depending on the elastic energy buildup and its possible release under specified structural tectonic conditions.</p>","PeriodicalId":56112,"journal":{"name":"Journal of Volcanology and Seismology","volume":"17 3","pages":"219 - 227"},"PeriodicalIF":0.7,"publicationDate":"2023-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4901042","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Choosing the Magnitude Range for Estimating the b-Value","authors":"V. F. Pisarenko,&nbsp;A. A. Skorkina,&nbsp;T. A. Rukavishnikova","doi":"10.1134/S0742046323700124","DOIUrl":"10.1134/S0742046323700124","url":null,"abstract":"<p>Modern seismological practice makes a wide use of the Gutenberg–Richter relation to describe the magnitude distribution. One of its parameters is the <i>b</i>-value (the slope of the earthquake recurrence curve in a log scale). This study proposes some new approaches to the problem of adequate and efficient statistical estimation of the parameter. We discuss the correct choice of the magnitude range over which the Gutenberg–Richter relation is a straight line to an acceptable degree of accuracy, and which should be used to estimate the <i>b</i>-value. We propose an efficient technique for incorporating discreteness and the grouping of magnitudes in earthquake catalogs (the method of maximum likelihood for discrete distributions). We discuss the problem of time-dependent variation for the lower threshold of complete earthquake reporting and propose a statistical approach to this variation.</p>","PeriodicalId":56112,"journal":{"name":"Journal of Volcanology and Seismology","volume":"17 2","pages":"75 - 82"},"PeriodicalIF":0.7,"publicationDate":"2023-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4136767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}