Pub Date : 2022-02-25DOI: 10.5026/jgeography.131.cover01_01
{"title":"Pumice Raft from August 2021 Eruption of Fukutoku-Oka-no-Ba Volcano, at Shidooke Beach, Kikaijima Island, Kagoshima","authors":"","doi":"10.5026/jgeography.131.cover01_01","DOIUrl":"https://doi.org/10.5026/jgeography.131.cover01_01","url":null,"abstract":"","PeriodicalId":45817,"journal":{"name":"Journal of Geography-Chigaku Zasshi","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2022-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41286314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-02-25DOI: 10.5026/jgeography.131.95
{"title":"Trends of Geosciences after the Pacific War in Japan, 1945 to 1965 Part 7","authors":"","doi":"10.5026/jgeography.131.95","DOIUrl":"https://doi.org/10.5026/jgeography.131.95","url":null,"abstract":"","PeriodicalId":45817,"journal":{"name":"Journal of Geography-Chigaku Zasshi","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2022-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41919802","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-02-25DOI: 10.5026/jgeography.131.47
M. Nogami
At the beginning of the 19 century Ino Tadataka surveyed almost all of Japan’s coastline and its main roads, and mapped them. He made ca. 70,000 magnetic azimuth measurements to perspective objectives such as mountain tops, isolated islands, and offshore rocks. Some of them are indicated on 1/216,000 maps with perspective lines and additional numeric characters. Differences between magnetic azimuth angles described on Ino’s map and true azimuth angles measured on current maps show the magnetic deviation at sites. A total of 555 sites and values were obtained across Japan, which were divided over 26 regions. Using 26 region-presentative values chosen statistically to mitigate errors, a magnetic deviation map of Japan at the beginning of 19 century was compiled.
{"title":"Making a Magnetic Deviation Map with Azimuth Survey Data of Ino Tadataka","authors":"M. Nogami","doi":"10.5026/jgeography.131.47","DOIUrl":"https://doi.org/10.5026/jgeography.131.47","url":null,"abstract":"At the beginning of the 19 century Ino Tadataka surveyed almost all of Japan’s coastline and its main roads, and mapped them. He made ca. 70,000 magnetic azimuth measurements to perspective objectives such as mountain tops, isolated islands, and offshore rocks. Some of them are indicated on 1/216,000 maps with perspective lines and additional numeric characters. Differences between magnetic azimuth angles described on Ino’s map and true azimuth angles measured on current maps show the magnetic deviation at sites. A total of 555 sites and values were obtained across Japan, which were divided over 26 regions. Using 26 region-presentative values chosen statistically to mitigate errors, a magnetic deviation map of Japan at the beginning of 19 century was compiled.","PeriodicalId":45817,"journal":{"name":"Journal of Geography-Chigaku Zasshi","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2022-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49155278","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-02-25DOI: 10.5026/jgeography.131.23
Jo Komuro
This study aims to elucidate the mechanisms for sustaining local labor markets in international mountain resorts according to their regional characteristics, focusing on foreign labor. It remains unclear how international mountain resorts, which have recently struggled to secure labor to accommodate a growing number of visiting tourists, have successfully attracted outside labor to sustain local labor markets. In this case study, Whistler is an example of a resort with an imbalance between the supply and demand of labor due to an increase in demand. When analyzing labor market results in this region, a mechanism emerges that includes two processes for supplying external labor. First, the process involving those who are willing to improve their language or professional skills and obtain permanent residence rights through work promotion, changing work, or starting businesses to establish themselves in a community. Second, the process of seasonal workers going abroad with working holiday visas and for recreational purposes. A specific social regulation effect overcomes three mismatches (space, temporal, and skills) and sustains these local labor markets. In other words, the international labor force travels abroad from one market to another when the spatial divergence is resolved. The process of permanent settlement or seasonal stay of workers is enabled by addressing the divergence between temporal elements and skills in these local labor markets.
{"title":"Mechanisms for Sustaining the Local Labor Markets in International Mountain Resorts: A Case Study of Whistler, Canada","authors":"Jo Komuro","doi":"10.5026/jgeography.131.23","DOIUrl":"https://doi.org/10.5026/jgeography.131.23","url":null,"abstract":"This study aims to elucidate the mechanisms for sustaining local labor markets in international mountain resorts according to their regional characteristics, focusing on foreign labor. It remains unclear how international mountain resorts, which have recently struggled to secure labor to accommodate a growing number of visiting tourists, have successfully attracted outside labor to sustain local labor markets. In this case study, Whistler is an example of a resort with an imbalance between the supply and demand of labor due to an increase in demand. When analyzing labor market results in this region, a mechanism emerges that includes two processes for supplying external labor. First, the process involving those who are willing to improve their language or professional skills and obtain permanent residence rights through work promotion, changing work, or starting businesses to establish themselves in a community. Second, the process of seasonal workers going abroad with working holiday visas and for recreational purposes. A specific social regulation effect overcomes three mismatches (space, temporal, and skills) and sustains these local labor markets. In other words, the international labor force travels abroad from one market to another when the spatial divergence is resolved. The process of permanent settlement or seasonal stay of workers is enabled by addressing the divergence between temporal elements and skills in these local labor markets.","PeriodicalId":45817,"journal":{"name":"Journal of Geography-Chigaku Zasshi","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2022-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41291727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-02-25DOI: 10.5026/jgeography.131.1
S. Hada, H. Goto
Two evolutionary lineages of the Neoshwagerinidae are recognized in the East TethysPanthalassa region in the mid-Permian time. These are the Misellina-Cancellina-ColaniaLepidolina and Misellina-Maklaya-Neoschwagerina-Yabeina evolutionary lineages. They formed distinctly isolated habitats in the Panthalassa region and are named the Colania-Lepidolina and Neoschwagerina-Yabeina territories, respectively. The paleogeographic distribution of the two territories is newly presented with an analysis of the Circum-Pacific accretionary complex combining the fusulinoidean faunas in mid-oceanic paleo-atoll limestones and the timing of their accretion clarified by radiolarian fossils. It is concluded that the Colania-Lepidolina territory expanded into a paleo-equatorial area in mid-Panthalassa with the Neoschwagerina-Yabeina territory at its southern side in the southern hemisphere. In East Paleo-Tethys, South China and Indochina continental blocks which were isolated in equatorial regions throughout the Permian period are striking territories characterized by an extension of the Lepidolina of the ColaniaLepidolina evolutionary lineage. On the Japanese Islands, Kurosegawa, Hida Gaien, South Kitakami and Maizuru belts are also characterized by the occurrence of Lepidolina.
{"title":"Mid-Permian Fusulinoidean Territories in Panthalassa","authors":"S. Hada, H. Goto","doi":"10.5026/jgeography.131.1","DOIUrl":"https://doi.org/10.5026/jgeography.131.1","url":null,"abstract":"Two evolutionary lineages of the Neoshwagerinidae are recognized in the East TethysPanthalassa region in the mid-Permian time. These are the Misellina-Cancellina-ColaniaLepidolina and Misellina-Maklaya-Neoschwagerina-Yabeina evolutionary lineages. They formed distinctly isolated habitats in the Panthalassa region and are named the Colania-Lepidolina and Neoschwagerina-Yabeina territories, respectively. The paleogeographic distribution of the two territories is newly presented with an analysis of the Circum-Pacific accretionary complex combining the fusulinoidean faunas in mid-oceanic paleo-atoll limestones and the timing of their accretion clarified by radiolarian fossils. It is concluded that the Colania-Lepidolina territory expanded into a paleo-equatorial area in mid-Panthalassa with the Neoschwagerina-Yabeina territory at its southern side in the southern hemisphere. In East Paleo-Tethys, South China and Indochina continental blocks which were isolated in equatorial regions throughout the Permian period are striking territories characterized by an extension of the Lepidolina of the ColaniaLepidolina evolutionary lineage. On the Japanese Islands, Kurosegawa, Hida Gaien, South Kitakami and Maizuru belts are also characterized by the occurrence of Lepidolina.","PeriodicalId":45817,"journal":{"name":"Journal of Geography-Chigaku Zasshi","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2022-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43584575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-02-25DOI: 10.5026/jgeography.131.115
K. Omoto
{"title":"Legal Procedure for Collecting Samples in a National Park Based on the Natural Parks Act: Example of Application Procedure for a Special Zone and a Marine Park Zone of Keramashoto National Park","authors":"K. Omoto","doi":"10.5026/jgeography.131.115","DOIUrl":"https://doi.org/10.5026/jgeography.131.115","url":null,"abstract":"","PeriodicalId":45817,"journal":{"name":"Journal of Geography-Chigaku Zasshi","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2022-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43309168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-25DOI: 10.5026/jgeography.130.811
R. Doke, K. Mannen, K. Itadera
Since a phreatic eruption is caused by ruptures in hydrothermal systems beneath volcanoes, detecting and monitoring a hydrothermal system can play an important role in predicting such an eruption. Interferometric Synthetic Aperture Radar (InSAR), which detects ground deformations over a large area, may be a key technology for use in various fields, as shown from the exponential growth of recent studies in terms of number and quality. The present contribution reviews surface deformations caused by the hydrothermal system of Hakone volcano, as detected by InSAR before, during, and after the 2015 eruption. The opening of the NWSE-trending crack and localized uplift in the Owakudani fumarole area were captured by InSAR analyses during the 2015 unrest at Hakone volcano. Moreover, an InSAR time series analysis showed steady subsidence on the west side of the Owakudani fumarole area. Based on models explaining these surface displacements, the shallow hydrothermal system of Hakone volcano is characterized by NW SE to WNWESE-trending crack-shaped fluid supply paths and pocket-shaped fluid reservoirs. During the 2015 and previous phreatic eruptions, it is probable that fluid was supplied using the same crack-like path, implying that fluid was repeatedly supplied using the same structure. Therefore, in order to predict the occurrence of phreatic eruptions at Hakone volcano, it is necessary to monitor volcanic activity by taking into account these structures. The activity of Hakone volcano, including formations of these NWSE to WNWESE-trending cracks, is dominated by a regional stress field. This stress field is caused by shear deformation due to plate motion occurring in this region; that is, the subducting Philippine Sea Plate, and the colliding Izu Peninsula.
{"title":"Structure of Shallow Hydrothermal System in Hakone Volcano, Japan, Inferred from Surface Displacements","authors":"R. Doke, K. Mannen, K. Itadera","doi":"10.5026/jgeography.130.811","DOIUrl":"https://doi.org/10.5026/jgeography.130.811","url":null,"abstract":"Since a phreatic eruption is caused by ruptures in hydrothermal systems beneath volcanoes, detecting and monitoring a hydrothermal system can play an important role in predicting such an eruption. Interferometric Synthetic Aperture Radar (InSAR), which detects ground deformations over a large area, may be a key technology for use in various fields, as shown from the exponential growth of recent studies in terms of number and quality. The present contribution reviews surface deformations caused by the hydrothermal system of Hakone volcano, as detected by InSAR before, during, and after the 2015 eruption. The opening of the NWSE-trending crack and localized uplift in the Owakudani fumarole area were captured by InSAR analyses during the 2015 unrest at Hakone volcano. Moreover, an InSAR time series analysis showed steady subsidence on the west side of the Owakudani fumarole area. Based on models explaining these surface displacements, the shallow hydrothermal system of Hakone volcano is characterized by NW SE to WNWESE-trending crack-shaped fluid supply paths and pocket-shaped fluid reservoirs. During the 2015 and previous phreatic eruptions, it is probable that fluid was supplied using the same crack-like path, implying that fluid was repeatedly supplied using the same structure. Therefore, in order to predict the occurrence of phreatic eruptions at Hakone volcano, it is necessary to monitor volcanic activity by taking into account these structures. The activity of Hakone volcano, including formations of these NWSE to WNWESE-trending cracks, is dominated by a regional stress field. This stress field is caused by shear deformation due to plate motion occurring in this region; that is, the subducting Philippine Sea Plate, and the colliding Izu Peninsula.","PeriodicalId":45817,"journal":{"name":"Journal of Geography-Chigaku Zasshi","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2021-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45845720","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-25DOI: 10.5026/jgeography.130.797
T. Ohba, T. Imura, Y. Minami, S. Angkasa
Steam-blast eruptions are classified into three categories: (1) hydrothermal eruption caused solely by a phase change of hydrothermal water within a hydrothermal system; (2) phreatic eruption caused by a new thermal input derived from a magma body in a sub-volcanic aquifer; and, (3) ultravulcanian eruption (gas eruption), a type of vulcanian eruption, which is caused by gas degassed from magma accumulating under a lava plug. It is proposed that these can be classified from a petrological analysis of eruption products based mainly on the authors’ previous contributions. Volcanic ash from hydrothermal eruptions is characterized by abundant altered lithics. At some composite volcanoes, altered lithics exhibit a wide variety of alteration types including siliceous, advanced argillic, phyllic, and potassic alterations, which are considered to originate from alteration zones of composite volcanoes. The association of alteration zones are correlated with those around porphyry copper deposits. The products of phreatic eruptions are composed mainly of strongly acid altered rocks, but may also contain fresh volcanic rock fragments. The rocks are derived from selectively/partially altered rocks under the crater. Ultravulcanian eruptions mainly release fresh lithic fragments and may also emit sulfur compound minerals (mainly sulfate), but the products contain no alteration minerals indicating hydrothermal acid leaching.
{"title":"Mechanisms of Steam-blast Eruptions Inferred from the Mineralogy of Volcanic Ash","authors":"T. Ohba, T. Imura, Y. Minami, S. Angkasa","doi":"10.5026/jgeography.130.797","DOIUrl":"https://doi.org/10.5026/jgeography.130.797","url":null,"abstract":"Steam-blast eruptions are classified into three categories: (1) hydrothermal eruption caused solely by a phase change of hydrothermal water within a hydrothermal system; (2) phreatic eruption caused by a new thermal input derived from a magma body in a sub-volcanic aquifer; and, (3) ultravulcanian eruption (gas eruption), a type of vulcanian eruption, which is caused by gas degassed from magma accumulating under a lava plug. It is proposed that these can be classified from a petrological analysis of eruption products based mainly on the authors’ previous contributions. Volcanic ash from hydrothermal eruptions is characterized by abundant altered lithics. At some composite volcanoes, altered lithics exhibit a wide variety of alteration types including siliceous, advanced argillic, phyllic, and potassic alterations, which are considered to originate from alteration zones of composite volcanoes. The association of alteration zones are correlated with those around porphyry copper deposits. The products of phreatic eruptions are composed mainly of strongly acid altered rocks, but may also contain fresh volcanic rock fragments. The rocks are derived from selectively/partially altered rocks under the crater. Ultravulcanian eruptions mainly release fresh lithic fragments and may also emit sulfur compound minerals (mainly sulfate), but the products contain no alteration minerals indicating hydrothermal acid leaching.","PeriodicalId":45817,"journal":{"name":"Journal of Geography-Chigaku Zasshi","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2021-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46176820","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-25DOI: 10.5026/jgeography.130.755
M. Iguchi
― ― Abstract On August 3, 2014 and May 29, 2015, eruptions occurred at the Shindake summit crater of Kuchinoerabujima volcano in the Ryukyu Islands, southwestern Japan. The Japan Meteorological Agency （ JMA ） upgraded the Volcanic Alert Level （ VAL ） to 3 （ warned zone within 2 km from the crater ） after the onset of the 2014 eruption and to 5 （ evacuation ） after the onset of the 2015 eruption. The possibility of implementing early warnings for eruptions and forecasting the area most likely to suffer damage from volcanic eruptions are examined based on monitoring data and disaster-affected areas of historic eruptions. The onset of the 2014 eruption was preceded by a 15-year prolonged increase in volcanic activity that started in July 1999. Only a short-term tilt change was observed immediately before the eruption. The prolonged volcanic activity is charac-terized by: 1 ） repeated bursts of seismicity; 2 ） ground inflation events around the crater associated with increases in seismicity; 3 ） increases in geothermal activity and 4 ） appearance of fuma-role. The short-term process consisted only of a tilt change of crater-side up one hour before the onset of the 2014 eruption. The phenomena prior to the 2015 eruption were more intense than those prior to the 2014 eruption, as demonstrated by seismicity, which included a felt earthquake six days before the eruption; larger ground deformation; higher rate of discharge of SO 2 gas; and, higher temperature. Despite more intense activity, VAL remained at 3. VAL was upgraded from 3 to 5 immediately after the 2015 eruption and then all of the residents were evacuated from the volcanic island by ferry boat. Decreases in seismicity, SO 2 gas discharge rate, and geothermal activity led to an initial reduction of the alert zone radius to less than 2.5 km in October 2015. A further reduction to less than 2 km （ VAL 3 ） was later implemented based on deflation around the summit area in June 2016. Problems related to evacuation
{"title":"Precursors to the 2015 Eruption of Kuchinoerabujima Volcano and Decision Making on Evacuation","authors":"M. Iguchi","doi":"10.5026/jgeography.130.755","DOIUrl":"https://doi.org/10.5026/jgeography.130.755","url":null,"abstract":"― ― Abstract On August 3, 2014 and May 29, 2015, eruptions occurred at the Shindake summit crater of Kuchinoerabujima volcano in the Ryukyu Islands, southwestern Japan. The Japan Meteorological Agency （ JMA ） upgraded the Volcanic Alert Level （ VAL ） to 3 （ warned zone within 2 km from the crater ） after the onset of the 2014 eruption and to 5 （ evacuation ） after the onset of the 2015 eruption. The possibility of implementing early warnings for eruptions and forecasting the area most likely to suffer damage from volcanic eruptions are examined based on monitoring data and disaster-affected areas of historic eruptions. The onset of the 2014 eruption was preceded by a 15-year prolonged increase in volcanic activity that started in July 1999. Only a short-term tilt change was observed immediately before the eruption. The prolonged volcanic activity is charac-terized by: 1 ） repeated bursts of seismicity; 2 ） ground inflation events around the crater associated with increases in seismicity; 3 ） increases in geothermal activity and 4 ） appearance of fuma-role. The short-term process consisted only of a tilt change of crater-side up one hour before the onset of the 2014 eruption. The phenomena prior to the 2015 eruption were more intense than those prior to the 2014 eruption, as demonstrated by seismicity, which included a felt earthquake six days before the eruption; larger ground deformation; higher rate of discharge of SO 2 gas; and, higher temperature. Despite more intense activity, VAL remained at 3. VAL was upgraded from 3 to 5 immediately after the 2015 eruption and then all of the residents were evacuated from the volcanic island by ferry boat. Decreases in seismicity, SO 2 gas discharge rate, and geothermal activity led to an initial reduction of the alert zone radius to less than 2.5 km in October 2015. A further reduction to less than 2 km （ VAL 3 ） was later implemented based on deflation around the summit area in June 2016. Problems related to evacuation","PeriodicalId":45817,"journal":{"name":"Journal of Geography-Chigaku Zasshi","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2021-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47740137","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-25DOI: 10.5026/jgeography.130.771
T. Hashimoto
― Abstract Volcanoes with shallow hydrothermal systems are often accompanied by background volcanic activity such as fumarolic activity, microseismicity, and ground deformation even in the non-eruptive phase. When elevated, they are said to be in a state of “unrest.” It is not difficult to imagine that such events of unrest reflect changes in the state of the shallow hydrothermal system beneath a volcano. However, there is currently no method by which these events can be used to quantitatively evaluate eruption imminency or predict eruption intensity based on physical and/or chemical models. A potentially useful application of such unrest events for probabilistically forecasting eruptions is discussed. First, the method proposed by Hashimoto et al . （ 2019 ） for compil-ing and evaluating the sources of unrest events, such as thermal demagnetization, is described. Then, the volcanic unrest index （ VUI ） of Potter et al . （ 2015a ） is proposed as another key tool. Finally, a concept is proposed for integrating the VUI and the unrest data to make probabilistically forecasting eruptions feasible. Also described is a recent attempt to introduce the VUI for evaluating a volcano in Japan. Information on sources of unrest in the form of the scatter plot of Hashimoto et al . （ 2019 ） can be used as one of the rating criteria on the VUI worksheet. The key idea is to divide the source diagram into regions based on the probability of posterior eruptions given unrest events and to assign VUI scores to these regions. Such a procedure may augment the VUI’s function, partially enabling probability-based eruption forecasting. Irrespective of whether the VUI is applied or not, it is essential to obtain temporally homogeneous monitoring data during both eruptive and non-eruptive periods for a quantitative evaluation of unrest events. Surveys and analyses carried out regularly over long time periods also play an equally important role. Therefore, to realize of probabilistic eruption forecasting, it is fundamentally important that monitoring networks are run properly and the data are shared appropriately.
{"title":"Utilizing Thermal Demagnetization Events to Evaluate Volcanic Unrest and the Prospects for Eruption Forecasting","authors":"T. Hashimoto","doi":"10.5026/jgeography.130.771","DOIUrl":"https://doi.org/10.5026/jgeography.130.771","url":null,"abstract":"― Abstract Volcanoes with shallow hydrothermal systems are often accompanied by background volcanic activity such as fumarolic activity, microseismicity, and ground deformation even in the non-eruptive phase. When elevated, they are said to be in a state of “unrest.” It is not difficult to imagine that such events of unrest reflect changes in the state of the shallow hydrothermal system beneath a volcano. However, there is currently no method by which these events can be used to quantitatively evaluate eruption imminency or predict eruption intensity based on physical and/or chemical models. A potentially useful application of such unrest events for probabilistically forecasting eruptions is discussed. First, the method proposed by Hashimoto et al . （ 2019 ） for compil-ing and evaluating the sources of unrest events, such as thermal demagnetization, is described. Then, the volcanic unrest index （ VUI ） of Potter et al . （ 2015a ） is proposed as another key tool. Finally, a concept is proposed for integrating the VUI and the unrest data to make probabilistically forecasting eruptions feasible. Also described is a recent attempt to introduce the VUI for evaluating a volcano in Japan. Information on sources of unrest in the form of the scatter plot of Hashimoto et al . （ 2019 ） can be used as one of the rating criteria on the VUI worksheet. The key idea is to divide the source diagram into regions based on the probability of posterior eruptions given unrest events and to assign VUI scores to these regions. Such a procedure may augment the VUI’s function, partially enabling probability-based eruption forecasting. Irrespective of whether the VUI is applied or not, it is essential to obtain temporally homogeneous monitoring data during both eruptive and non-eruptive periods for a quantitative evaluation of unrest events. Surveys and analyses carried out regularly over long time periods also play an equally important role. Therefore, to realize of probabilistic eruption forecasting, it is fundamentally important that monitoring networks are run properly and the data are shared appropriately.","PeriodicalId":45817,"journal":{"name":"Journal of Geography-Chigaku Zasshi","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2021-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45004821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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