Journal of Volcanology and Seismology最新文献

{"title":"Time-dependent Travel Time Tomography in NW Iran","authors":"Rahim Jomeiri,&nbsp;Esmaeil Bayramnejad,&nbsp;Zaher Hossein Shomali","doi":"10.1134/S0742046324700854","DOIUrl":"10.1134/S0742046324700854","url":null,"abstract":"<p>4-D seismic tomography study was conducted in the northwestern region of Iran using travel time tomography during 1996 to 2016. The study area is situated within the active tectonic and seismic zones of the collision between the Eurasian and Arabian plates. This region has experienced multiple significant and destructive earthquakes in the past. Furthermore, it includes Lake Urmia, which has undergone a substantial decrease in water level by about 8 meters during the study period. To minimize the artifacts caused by uneven distribution of seismic rays, similar data sets including about 700 earthquakes in each period were selected for five periods. Subsequent experiments utilizing synthetic models demonstrated that the selected subsets of data for different time periods have the potential to identify anomalies in different periods. 3-D tomography was performed for each selected data sets, and the results were compared across different time periods. The results, focused on two depths of 8 and 23 kilometers and receiving significant attention, exhibit certain similarities in the observed anomalies across different time periods. These anomalies correspond to the tectonic structures of the region. Some differences are also observed among the various time periods. The trends of most anomalies and the differences in velocity models across different time periods are consistent with the general trends of the active faults in the area. The majority of the differences in velocity models for different time periods are observed at a depth of 8 km, along northwest-southeast-trending faults.</p>","PeriodicalId":56112,"journal":{"name":"Journal of Volcanology and Seismology","volume":"19 1","pages":"93 - 111"},"PeriodicalIF":0.7,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143830871","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":"Epithermal Au–Ag Mineralization in Terrigenous Rock Sequences in the Basement of the Pechalninskaya Volcanic Dome Structure, Northeast Russia","authors":"V. M. Kuznetsov,&nbsp;N. E. Savva,&nbsp;A. V. Volkov,&nbsp;K. Yu. Murashov,&nbsp;A. L. Galyamov,&nbsp;A. V. Grigorieva","doi":"10.1134/S0742046324700891","DOIUrl":"10.1134/S0742046324700891","url":null,"abstract":"<p>The epithermal Au–Ag mineralization at the Pechalnoe deposit is of considerable interest, since it was formed in carbonaceous terrigenous rock sequences making the basement of a volcanic dome structure at a distance of about 200 km from the boundary of the Okhotsk–Chukchi marginal continental volcanic belt. The geological structure of the Pechalnoe deposit consists of two levels, quartz–adularia and quartz Au–Ag veins are localized in keratinized terrigenous rocks of the lower level, while the quartz rhyolites and comendites of the Pechalninskaya rock sequence in the upper level harbor potential industrially valuable REE mineralization. The productive veins make three zones striking nearly east–west; the veins in these zones are 200–300 m long, occasionally reaching 640, 840 m; the mean thickness is 0.1–3 m, rarely reaching 6.2 m; the mean concentrations are Ag 266 g/t, Au 4.4 g/t. The following mineralogical features of the ores have been identified: low sulfides (1‒2%); the productive minerals are native Ag, low fineness Au, polybasite, and high-selenium acanthite. In addition, the ores have abundant enough arseniferous pyrite, arsenopyrite, pyrrhotine, ferruginous sphalerite, chalcopyrite, and marcasite. The geochemical features of the ores are in good agreement with their mineral composition. The ores are enriched in a wide range of trace elements (arranged in decreasing concentration): Ag, Au, As, Sb, Sе, W, Tl, Li, Be, Bi, Cs, and Mo; light lanthanoids prevail over heavy ones; very low Eu/Sm ratios (<span>( ll 1)</span>), little inclined near-chondrite distributions (without distinct europium maxima or minima); the relationship between Ce/Ce* and Eu/Eu* indicates oxidizing conditions during the mineralization; the REE spectra are dominated by light “hydrophile” lanthanoids of the “cerium” group; ΣREE varies in a wide range. The mineralogical and geochemical data obtained enable us to classify the Pechalninskaya mineralization as belonging to the selenium subtype of the low sulfide class of epithermal deposits. According to geological and mineralogic-geochemical evidence, the deposit can be classified as poorly eroded, which suggests future identification of new ore bodies not at the ground surface.</p>","PeriodicalId":56112,"journal":{"name":"Journal of Volcanology and Seismology","volume":"19 1","pages":"30 - 47"},"PeriodicalIF":0.7,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143830784","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":"Applying the Nearest Neighbor Method to the Analysis of Volcanic Swarms Based on Data for Bárðarbunga and Fagradalsfjall Volcanoes","authors":"E. M. Grekov","doi":"10.1134/S0742046324700866","DOIUrl":"10.1134/S0742046324700866","url":null,"abstract":"<p>This study presents an analysis of event clustering in volcanic seismicity, especially in volcanic swarms. We have analyzed the volcanic swarms occurring during the eruptions of Bárðarbunga (2014) and Fagradalsfjall (2021) volcanoes in Iceland, attempting to use the nearest neighbor method for this goal. The method enables identification of clusters with different scales of generalized distance; as an example, the method generally identifies two clusters of events in tectonic seismicity and is widely used in aftershock identification. We have detected considerable differences in the distributions of generalized distance to the nearest neighbor for volcanic seismicity compared with tectonic seismicity. To be more specific, we have discovered two types of unimodal distribution, with the one mostly occurring before eruptions and the other during eruptions. The former type is probably due to coalescence of two near modes in the distribution, and reflects an internal inhomogeneity in seismicity during such periods. However, the unimodal nature of the distributions makes it difficult to identify events viewed as interrelated (clustered) or independent (background events). It can be surmised based on the results obtained that, before an eruption, the percentage of background seismicity fluctuates around 70%, while being between 90 and 100% during the eruption. This can be considered as providing evidence of different sources of seismicity during different phases of an eruption.</p>","PeriodicalId":56112,"journal":{"name":"Journal of Volcanology and Seismology","volume":"19 1","pages":"78 - 92"},"PeriodicalIF":0.7,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143830786","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 Verkhne-Yuriev Thermal Springs: The Evolution of Chemical and Isotope Compositions (1952–2022) in Relation to Active Periods of Ebeko Volcano, Paramushir Island","authors":"E. G. Kalacheva,&nbsp;T. A. Kotenko,&nbsp;E. V. Voloshina,&nbsp;D. Yu. Erdnieva,&nbsp;D. V. Melnikov","doi":"10.1134/S0742046324700908","DOIUrl":"10.1134/S0742046324700908","url":null,"abstract":"<p>This paper describes the chemical composition of the thermal waters discharging on the northwestern slope of the active Ebeko Volcano in the Yuriev River valley. We are using continuous multiyear observations of the evolution of chemical and isotope compositions to estimate the response of volcanic events to the state of the hydrothermal system. It is shown that phreatomagmatic eruptions of the volcano were preceded by a change in the chemical and isotope compositions of thermal waters caused by increased inflow of magmatic volatiles into the system. The springs are observed to show increased concentrations of anion-generating components (chloride, sulfate, and fluorine ions) with concurrent increases in heavier isotopes of oxygen and hydrogen (deuterium) toward “andesitic” water. Recalling that the changes were detected a few months before the eruption, we infer that such geochemical effects can serve as predictive markers when monitoring the state of the volcano.</p>","PeriodicalId":56112,"journal":{"name":"Journal of Volcanology and Seismology","volume":"19 1","pages":"13 - 29"},"PeriodicalIF":0.7,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143830782","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 Earthquake Prediction, the Relationship between Seismic and Geodynamic Processes, and the Concept of Information Certainty","authors":"A. V. Solomatin","doi":"10.1134/S0742046324700878","DOIUrl":"10.1134/S0742046324700878","url":null,"abstract":"<p>We are considering in a general form several problems that have to be dealt with in prediction of great earthquakes, which pose the greatest hazard. The most important of these problems include the following: the efficiency of earthquake prediction based on the concept of scenarios, which represent the basic patterns in the evolution of the source zones generating great earthquakes; monitoring the development of such scenarios on the basis of seismological data; modeling the relationship between seismic and geodynamic processes that control the scenarios. We suggest for dealing with the last two problems to use concepts of energy and dynamic spectra of seismic activity in the geomedium, while the solution we propose has a certain peculiarity, namely, introduction of a mathematical concept of information certainty. An example in the use of proposed procedures as set forth in this paper consists in a substantiation of the hypothetical multiyear oscillating movement as the oceanic plate is subducted in the Kamchatka subduction zone at a period of about 8.57 years. It is supposed that such oscillations essentially control the most likely periods in the occurrence of regional great earthquakes.</p>","PeriodicalId":56112,"journal":{"name":"Journal of Volcanology and Seismology","volume":"19 1","pages":"67 - 77"},"PeriodicalIF":0.7,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143830785","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":"Sources of the Melts of Quaternary Hauyne Alkaline Basaltoids in the Lesser Caucasus. Communication 1. Geochemical and Isotope (Sr‒Nd‒Pb) Data","authors":"S. N. Bubnov,&nbsp;Yu. V. Goltsman,&nbsp;I. A. Kondrashov,&nbsp;T. I. Oleinikova,&nbsp;A. Ya. Dokuchaev","doi":"10.1134/S0742046324700799","DOIUrl":"10.1134/S0742046324700799","url":null,"abstract":"<p>The first detailed data are obtained on the Sr‒Nd‒Pb isotope systematics and geochemistry of Quaternary intraplate hauyne basanites and ordanshites in the Lesser Caucasus. The parental magmas of the rocks were found out to have been generated by mixing material from at least two regional sources: one relatively depleted and the other significantly enriched in incompatible elements. One of these sources of the hybrid magmas was most likely a mildly depleted regional plume–asthenospheric source of the CAUCASUS OIB type, whose isotopic-geochemical signatures were close to those of the COMMON and PREMA mantle reservoirs. The other source of the material for the rocks was relatively enriched in radiogenic Sr and Pb and depleted in radiogenic Nd and was most probably enriched subcontinental lithospheric mantle of the EM II type.</p>","PeriodicalId":56112,"journal":{"name":"Journal of Volcanology and Seismology","volume":"18 6","pages":"560 - 583"},"PeriodicalIF":0.7,"publicationDate":"2024-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142889480","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 Pacific Tsunamigenic Earthquakes in the Early 2024","authors":"G. I. Dolgikh,&nbsp;S. G. Dolgikh","doi":"10.1134/S0742046324700842","DOIUrl":"10.1134/S0742046324700842","url":null,"abstract":"<p>We are using data for two tsunamigenic earthquakes to develop a procedure for determining the displacement of sea bottom giving rise to tsunamis. We show that, assuming an average geometrical spreading factor for strain anomalies recorded by a laser strainmeter worldwide, we can find an approximate estimate of sea bottom displacement at a tsunamigenic site. There are more accurate spreading factors for each region where tsunamis have been generated; these can be estimated experimentally to be used for more accurate determination of sea bottom displacements.</p>","PeriodicalId":56112,"journal":{"name":"Journal of Volcanology and Seismology","volume":"18 6","pages":"509 - 514"},"PeriodicalIF":0.7,"publicationDate":"2024-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142890428","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":"Determining the Seismicity Parameters to Assess the Earthquake Hazard for Irkutsk Region","authors":"P. N. Shebalin,&nbsp;I. A. Vorobieva,&nbsp;S. V. Baranov,&nbsp;A. A. Kovalenko,&nbsp;A. I. Livinsky,&nbsp;A. A. Lykova","doi":"10.1134/S0742046324700829","DOIUrl":"10.1134/S0742046324700829","url":null,"abstract":"<p>This paper is concerned with the determination of seismicity parameters for Irkutsk Region. To tackle this problem, we have made a complete earthquake catalog for the region using a unified magnitude scale for the time span from 1962 to 2021 inclusive. The determination of seismicity parameters is an important task prior to obtaining subsequent estimates of earthquake hazard. The solution of the problem is extremely important for insurance and reinsurance businesses, since it appears feasible to employ the probabilistic approach with utmost accuracy when dealing with assessment of seismic risk, and this in turn ensures that the best management decisions are taken in order to make a stable financial system of the company concerned.</p>","PeriodicalId":56112,"journal":{"name":"Journal of Volcanology and Seismology","volume":"18 6","pages":"524 - 531"},"PeriodicalIF":0.7,"publicationDate":"2024-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142890432","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 of the Seismic Rupture Surface of the January 22, 2024 Aykol, China, Earthquake Based on SAR Interferometry Data","authors":"E. P. Timoshkina,&nbsp;A. M. Konvisar,&nbsp;V. O. Mikhailov,&nbsp;A. V. Ponomarev,&nbsp;V. B. Smirnov","doi":"10.1134/S0742046324700830","DOIUrl":"10.1134/S0742046324700830","url":null,"abstract":"<p>In this study we present the model of the rupture surface of the <i>M</i>_W = 7.0 Aykol earthquake, which occurred on the border of PRC and Kyrgyzstan on January 22, 2024, as well as the model of the rupture surface of its strongest aftershock on January 29, 2024, with magnitude <i>M</i>_W = 5.7 based on satellite radar interferometry data. We derived displacement fields of the Earth’s surface in the satellite line of sight for these events using Sentinel-1A imagery and resolved the inverse problem of estimating displacement fields on the rupture surfaces. The resulting rupture surface models reveal the presence of fault systems dipping towards one another. The fault plane of the main event is a thrust with left-lateral shear component dipping to the northwest. During the development of the aftershock process, a backthrust dipping to the southeast developed in the frontal region, displacing the western portion of the frontal thrust formed during the main shock. Such fault dynamics is a result of the complex structure of the fault zones in the studied region. Backthrusts in this area had been mapped during previous field works.</p>","PeriodicalId":56112,"journal":{"name":"Journal of Volcanology and Seismology","volume":"18 6","pages":"515 - 523"},"PeriodicalIF":0.7,"publicationDate":"2024-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142890430","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 October 18 and 25, 2017 Earthquakes in Western Transbaikalia: Confirming the Present-Day Activity of Local Faults","authors":"Ya. B. Radziminovich,&nbsp;A. I. Filippova,&nbsp;V. I. Melnikova,&nbsp;N. A. Gileva","doi":"10.1134/S0742046324700805","DOIUrl":"10.1134/S0742046324700805","url":null,"abstract":"<p>This paper considers two earthquakes which occurred on October 18, 2017 and October 25, 2017 in western Transbaikalia. In spite of the moderate energy level of both events, they can be treated as significant for the study area, because such earthquakes have been recorded there relatively rarely compared with the adjacent high-seismicity areas in the Baikal Rift Zone. The mechanisms of both earthquakes based on surface wave amplitude spectra showed that these events occurred under a dominating east–west near-horizontal compression and an inclined or nearly vertical NW‒SE tension, which is typical for western Transbaikalia. For both earthquakes, we also computed source parameters: scalar seismic moment <i>M</i>₀ = 5.0 × 10¹⁵ N m, moment magnitude <i>M</i>_w = 4.4, and source depth <i>h</i> = 7 km for the October 18, 2017 event; <i>M</i>₀ = 3.5 × 10¹⁵ N m, <i>M</i>_w = 4.3, and <i>h</i> = 29 km for the October 25, 2017 event. These earthquakes have caused noticeable macroseismic effects in the near-field; the maximum observed shaking intensity was IV–V (MSK-64) during the October 18, 2017 earthquake and V during the October 25, 2017 earthquake. These data were the basis for our analysis of present-day activity of faults in the study area. The results may be helpful for more accurate assessment of earthquake hazard and seismic risk in western Transbaikalia.</p>","PeriodicalId":56112,"journal":{"name":"Journal of Volcanology and Seismology","volume":"18 6","pages":"544 - 559"},"PeriodicalIF":0.7,"publicationDate":"2024-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142890406","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}