Northwestern Kyushu Research Articles

Detection of long-term slope displacement using time-series DInSAR and geological factor analysis for susceptibility assessment of landslides in northwestern Kyushu Island

Ongoing climate change has increased the impact of landslides and related slope disasters on infrastructure and human lives. Microwave satellite remote sensing, particularly interferometric analysis of synthetic aperture radar (InSAR) data, is a powerful tool for routine monitoring of the displacement of slopes on small wavelength scales, independently from solar illumination and cloud coverage. Although various sophisticated techniques for time-series InSAR have been developed, practical application in conjunction with geological analysis to reveal intrinsic and triggering factors of slope displacement is still limited. In this paper, we describe a practical case of time-series InSAR analysis with a special focus on its geological implications in northwestern Kyushu, a high-risk area for slope-related disasters in Japan. The extracted susceptible polygons from the InSAR results show accuracy comparable with that of other recent research on landslide mapping. Intrinsic factor analysis based on a geographic information system reveals that the displacement occurs on relatively gentle slopes instead of steep areas, corresponding to the transient zone of Paleogene-Neogene sedimentary rocks and basalt. Triggering factor analysis based on correlation coefficients reveals a significant link between some displacement areas with mean and/or maximum precipitation for each observation duration. Those findings confirm the importance of carefully accounting for the geological background for landslide susceptibility assessment and policy making, apart from topographic and meteorological conditions.

Movement range of brown chub <i>Kyphosus bigibbus</i> and its seasonal change on the reefs of Iki Island, northwestern Kyushu, revealed using biotelemetry

Movement range of brown chub <i>Kyphosus bigibbus</i> and its seasonal change on the reefs of Iki Island, northwestern Kyushu, revealed using biotelemetry

한국 융기문토기의 연대 재고

Raised-design pottery is a type of pottery representative of the early Neolithic period in Korea. Particularly in the southern part of the Korean peninsula, pottery was divided into four types and created a long tradition of pottery lasting about 1,000 years. It is a well-known fact among Neolithic researchers in both countries, Korea and Japan that this type of pottery has been found in many coastal sites in the northwestern Kyushu region in Japan. In particular, the Koshitaka Site on Tsushima Island, Nagasaki Prefecture, is famous for the discovery of many pottery of the first half of the comb-patterned pottery, which is common to the southern part of the Korean peninsula, including Raised-design pottery. We, the Department of Archaeology, Kumamoto University, have conducted excavations at this site four times since 2015, jointly with the Tsushima Board of Education, and have obtained various information about the characteristics of the site that were not well understood until now. This paper examines the revision of the age of Raised-design pottery, one of the results of excavations that could not be fully explained due to the limited number of characters in the previous report, by adding new materials. In analyzing the dating values, we studied the types of charcoal, seeds, and charcoal attached to pottery, examined the presence or absence of a marine reservoir effect by the C value, and performed calibration using IntCal 20 and Marine 20. As a result, the age values indicated by the plant samples showed the most reliable age values, and in the case of Korean Neolithic sites located on the coast, it was reconfirmed that the influence of the marine reservoir effect is large. Although Raised-design pottery in southern Korea and Tsushima follow almost the same pattern changes, we concluded that the existing chronology of Raised-design pottery in Korea is about 400 years older than the new chronology based on reliable age values and that a revision is necessary.

Preliminary assessment of genetic variation in the Japanese endemic freshwater crab, Geothelphusadehaani, based on mitochondrial DNA sequences.

Geothelphusadehaani, a freshwater crab species endemic to Japan, has the largest distribution range amongst the 19 known species in the country. Due to its low dispersal capability and restricted habitat to freshwater, it serves as an excellent model for understanding gene flow between geographically isolated populations. In this study, we analysed the genetic relationships of 26 G.dehaani populations collected from different locations in the Japanese archipelago using two mitochondrial DNA regions - cytochrome oxidase subunit I (COI) and cytochrome b (cytB). Our results from the analysis of molecular variance (AMOVA) revealed high genetic variation amongst populations and the phylogenetic analysis identified four geographical groups: Clade I - Honshu and Shikoku, Clade II - north-eastern Kyushu, Clade III - southern Kyushu and Clade IV - north-western Kyushu. Notably, Clade IV exhibited the highest genetic distance amongst the observed groupings. These findings highlight the need for further examination of G.dehaani in Kyushu, including morphological and behavioural traits, to better understand the observed diversity within the species in the region.

Unearthing Practice: Networked Authenticity and Sutra Interment

abstract: In this article, I conduct a case study of sutra-interment rituals conducted at Buzōji in northwestern Kyushu. Placing twelfth-century practices of sutra burial into creative dialogue with twentieth-century practices of sutra excavation, I propose a model of "networked authenticity." Thinking about authenticity as networked—distributed across several interconnected nodes—rather than as generated from any single point provides a way of valuing devotional attention as sincere and meaningful, even when aspects of specific instances of devotion may be imperfect. This model opens a way to evaluate the efficacy of imagined traditions, rotted manuscripts, looted sites, and apocryphal texts by recognizing them as part of a larger, interconnected web whose strands may span centuries. I show that sacred texts are products of social negotiation around meaning and authenticity, not the sources of it. 摘要: 本稿では 12 世紀と 20 ・ 21 世紀武蔵寺経塚と写経埋納法会をケーススタディとして、信仰的な「信憑性」の構造を考察する。結論としては、信憑性の源流は一つ (例えば経典) ではなくて、却っていくらの要素、つまりネットワークで組み立てされる。

Western End of Late Cretaceous Fore-arc Basin and Provenance in SW Japan: Detrital Zircon U–Pb Dating of Upper Cretaceous–Paleogene Sandstones in Nagasaki-Nishisonogi Peninsula, Western Kyushu

Uranium–Pb ages of detrital zircons taken from seven sandstone samples collected at what were previously called “Paleogene strata” in the Nagasaki and Nishisonogi Peninsula, northwestern Kyushu, SW Japan are measured. Depositional ages of three sandstones in the Nagasaki peninsula are revealed to be e Campanian–Maastrichtian (Late Cretaceous) or younger. Depositional ages of two sandstones in Terashima Island off the west coast of the Nishisonogi Peninsula are likewise dated as Campanian or younger. By contrast, two sandstones in western Nagasaki Peninsula are confirmed as the Ypresian–Lutetian (Eocene) or younger. These new ages are concordant with sporadically reported mollusk fossils, basically supporting the previous stratigraphic scheme, except for a distinct Upper Cretaceous strata called the Mitsuze Formation. The age spectra of detrital zircons from the four Campanian sandstones share the same pattern; i.e., ranging in the Aptian–Campanian with a peak around the Cenomanian. The Maastrichtian sandstone has grains ranging in the Albian–Maastrichtian with a peak around the Turonian, which is slightly younger than that of Campanian sandstones. Judging from the dominance of Middle Cretaceous zircon grains, the main provenances of the sandstones are probably the Ryoke/San-yo and San-in granite belts in SW Japan, where Middle to Late Cretaceous felsic igneous rocks are extensively exposed. The age spectra of detrital zircons in the Campanian–Maastrichtian sandstones are almost identical to those of the Himenoura and Mifune groups in central Kyushu, and the Izumi Group in Shikoku/western Kii peninsula. All of these units were deposited unconformably over the Ryoke granitoids. Within the elongated arc-trench system extending for over 1,300 km from western Kyushu to northern Kanto, Mitsuze Formation sandstones in the Nagasaki-Nishionogi Peninsula mark the known western end of the large-scale Upper Cretaceous fore-arc basin in Japan.

Inter-Changeable Religions: A Style of Japanese Religious Pluralism in Hirado Island Villages, Northwestern Kyushu

Inter-Changeable Religions: A Style of Japanese Religious Pluralism in Hirado Island Villages, Northwestern Kyushu

Significant Asymmetry of the Bilateral Upper Extremities of a Skeleton Excavated from the Mashiki-Azamabaru Site, Okinawa Island, Japan.

The human skeleton of a young adult male with marked asymmetry of the bilateral upper extremities was excavated from the Mashiki-Azamabaru site (3000–2000 BCE) on the main island of Okinawa in the southwestern archipelago of Japan. The skeleton was buried alone in a corner of the cemetery. In this study, morphological and radiographic observations were made on this skeleton, and the pathogenesis of the bone growth disorder observed in the left upper limb was discussed. The maximum diameter of the midshaft of the humerus was 13.8 mm on the left and 21.2 mm on the right. The long bones comprising the left upper extremity lost the structure of the muscle attachments except for the deltoid tubercle of the humerus. The bone morphology of the right upper extremity and the bilateral lower extremities was maintained and was close to the mean value of females from the Ohtomo site in northwestern Kyushu, Japan, during the Yayoi period. It is assumed that the anomalous bone morphology confined to the left upper extremity was secondary to the prolonged loss of function of the muscles attached to left extremity bones. In this case, birth palsy, brachial plexus injury in childhood, and acute grey matter myelitis were diagnosed. It was suggested that this person had survived into young adulthood with severe paralysis of the left upper extremity due to injury or disease at an early age.

Long-term change and disappearance of Lessoniaceae marine forests off Waka, Ikishima Island, northwestern Kyushu, Japan

Long-term change and disappearance of Lessoniaceae marine forests off Waka, Ikishima Island, northwestern Kyushu, Japan

High Clonality and Geographically Separated Cryptic Lineages in the Threatened Temperate Coral, Acropora pruinosa

Acropora pruinosa is a threatened zooxanthellate scleractinian coral that is distributed in the temperate areas along the coastline of Japan and the northern area of the South China Sea. Since A. pruinosa propagates both asexually and sexually, assessing clonal diversity and genetic connectivity among populations is important for conservation. In addition, high morphological variations in the field create confusion during species identification. To examine the existence of hidden genetic lineages, clonality, and genetic connectivity of A. pruinosa for conservation, we applied microsatellite analysis. Clustering analysis indicated two distinct geographically separated genetic lineages: one is distributed in the west, and the other is distributed in the east. The two lineages co-existed in Nishidomari, Kochi. There was no obvious difference in morphological characteristics between the two lineages. Although the factors influencing the observed distribution patterns remain unknown, there is a possibility that the two lineages might have diverged somewhere in the north-western Kyushu and north-eastern Pacific coast habitats in the past, and then periodically colonized the current habitats. A low clonal diversity was observed in most of the populations, indicating a high rate of asexual reproduction associated with their branching morphologies. In addition, there are strong genetic structuring in this species, indicating weak connectivity among populations. These results indicated a low larval dispersal potential among populations and that populations are basically sustained by a high rate of clone propagation and self-seeding. The existence of cryptic lineages and genetically isolated populations with high clonality emphasized the importance of conservation of A. pruinosa.

Petrogenetic implications and geochronology of middle Miocene Tannayama igneous rocks, Goto Islands, Japan Sea southern margin, northwestern Kyushu, Japan

AbstractThe subduction of “hot” Shikoku Basin and the mantle upwelling related to the Japan Sea opening have induced extensive magmatism during the middle Miocene on both the back‐arc and island‐arc sides of southwest Japan. The Goto Islands are located on the back‐arc side of northwestern Kyushu, and middle Miocene granitic rocks and associated volcanic, hypabyssal, and gabbroic rocks are exposed. The igneous rocks at Tannayama on Nakadori‐jima in the Goto Islands consist of gabbronorite, granite, granite porphyry, diorite porphyry, andesite, and rhyolite. We performed detailed geological mapping at a 1:10 000 scale, as well as petrographical and geochemical analyses. We also determined the zircon U–Pb age dating of the igneous rocks from Tannayama together with a granitic rock in Yagatamesaki. The zircon U–Pb ages of the Tannayama igneous rocks show the crystallization ages of 14.7 Ma ± 0.3 Ma (gabbronorite), 15.9 Ma ± 0.5 Ma (granite), 15.4 Ma ± 0.9 Ma (granite porphyry), and 15.1 Ma ± 2.1 Ma (rhyolite). Zircons from the Yagatamesaki granitic rock yield 14.5 Ma ± 0.7 Ma. Considering field relationships, new zircon data indicate that the Tannayama granite formed at ~16–15 Ma, and the gabbronorite, granite porphyry, diorite porphyry, andesite, and subsequently rhyolite formed at 15–14 Ma, which overlaps a plutonic activity of the Yagatamesaki. The geochemical characteristics of the Tannayama igneous rocks are similar to those of the tholeiitic basalts and dacites of Hirado, and the granitic rocks of Tsushima in northwestern Kyushu. This suggests that the Tannayama igneous rocks can be correlated petrogenetically with the igneous rocks in those areas, with all of them generated by the upwelling of hot mantle diapirs during crustal thinning in an extensional environment during the middle Miocene.

Rigid migration of Unzen lava rather than flow

We have reassessed the mode of advance of lava erupted in the 1990s from Unzen Fugen-dake Volcano in northwestern Kyushu, Japan. The apparent viscosity of Unzen lava had been estimated to be 0.9–4.2 × 1010 Pa s from the observed lava surface velocity in 1991, using Jeffreys model, based on the assumption that the lava was a Newtonian or Bingham fluid. In contrast, the viscosity of synthetic groundmass glass derived from Unzen lava had been measured in the laboratory at expected lava temperatures (780 °C–880 °C) to be 1011–1013 Pa s, considerably higher than the viscosity based on field observation. If the suspension effect of crystals is taken into consideration for groundmass glass, several orders of magnitude higher viscosity than observed should be expected for Unzen lava. To seek the source of the disparity in viscosity estimates, we first performed uniaxial-compression viscometry on natural Unzen lava samples collected in 1991 and thereby confirmed that the lava viscosity was actually higher than determined by field observations and equal to or higher than the fluid–solid threshold viscosity (1012 Pa s). This suggests that the observational viscosity had been underestimated. From reanalysis of the lava migration using video and photographs, contemporaneous with the field-based viscosity estimation, we found that the lava behavior was far from that of a fluid. Apparently, the lava lobe lost its fluidity at the flow front and instead advanced rigidly, thereby indicating that the application of Jeffreys model had incorrectly led us to underestimate viscosity. Although we used only the 1991 lava samples and image data, we infer that rigid migration was common for all exogenous lava lobes during the 1991–1995 activity. Our comparative study demonstrates that cooled and/or degassed lavas could show higher mobility than expected from experiment- or model-based viscosity. Apparently this occurs when the frictional force is smaller between lobe base and underlying slope than the viscous resistance inherent in lava.

A multigene molecular phylogeny of Eisenia reveals evidence for a new species, Eisenia nipponica (Laminariales), from Japan

ABSTRACTRecently, synonymizing Eisenia with Ecklonia was suggested based on a molecular phylogeny using the rbcL gene and ITS1–5.8S rDNA sequences. However, in a multigene molecular phylogeny based on mitochondrial cox1, cox3 genes and the atp8–16S rDNA region, as well as the plastid atpB, psaA, psbA and rbcL genes, Ecklonia spp. formed a monophyletic clade supported by high statistical values, and Eisenia spp. showed monophyly depending on analytical methods. The Japanese Eisenia species that used to be identified as Eisenia arborea (E. arborea sensu Arasaki) was shown to be genetically distant from E. arborea from the NE Pacific and E. bicyclis from Japan. Eisenia spp. were morphologically distinct in having a split meristematic zone in the mature thallus forming a dorsi-ventral blade with false branches. Therefore, we propose reinstatement of Eisenia as an independent genus and describe a new species, Eisenia nipponica (= E. arborea sensu Arasaki) from Japan. E. nipponica is distributed on the Pacific Coast of central Honshu, having a separate geographic range from E. bicyclis, which is distributed on the Pacific coast of eastern Honshu and the Sea of Japan coast of north-western Honshu and northern Kyushu.

Application of a fish finder system to spatial distribution mapping for the razor clam Solen gordonis: Case study from coastal waters, northwestern Kyushu, Japan

Effective spatial management planning for sedentary fishery resources requires accurate spatial distribution mapping of a focal stock including both fished and associated unfished populations. This study focuses on (sub-)adult razor clams (Solen gordonis), with shell lengths ≥25 mm, in Sasebo Bay and Omura Bay, northwestern Kyushu, Japan. They are commercially harvested, but little is known about their spatial distribution pattern. The objective was to estimate the spatial distribution and configuration of clam beds existing within an area of ca. 12 km2. For this, clam and sediment sampling by scuba-equipped divers, acoustic bathymetric surveys using a recreational-grade fish finder (single-beam acoustic) system, and presence–absence modelling using generalized linear models were performed. For the collected clams, catch per unit effort (CPUE; number of clams collected/h) was calculated and used as a proxy for clam individual density. The results showed that the presence–absence variation in the spatial distribution of (sub-)adult clams was associated with the bottom sediment type. (Sub-)adult clams occurred frequently in the sediments with higher gravel (particles with diameters ≥2 mm, mainly shell fragments) and lower mud (diameters <0.063 mm) contents than the sediments of the absence sites. Acoustic signals of the fish finder system were backscattered more intensely from gravel-sand beds (i.e., typical of the presence sites) than from muddy sand beds (i.e., absence sites). Using the relationships among the presence–absence variation of (sub-)adult clams, sediment type, and backscatter strength, spatial distribution of clams was predicted with high accuracy. The presence probability of (sub-)adults (= x; continuous values from 0 to 1) predicted from the results was significantly regressed on CPUE (= y) [i.e., y = exp(−0.7984 + 4.9350x) − 0.05]. Using this relationship, a map for the relative abundance of (sub-)adult clams was obtained. This map depicted several clam beds including both exploited and unexploited ones. The latter beds virtually conform to no-take zones in the razor clam fishery.

A Study on the trade between Yeongnam and Northwestern Kyushu coastal regions: based on the aspect of fishing tools

The trade between Yeongnam and Northwestern Kyushu coastal regions (YNKR) had occurred around the Korea Straits and could be understood as an exchange between fishermen of the two regions in the nature of costal regions. In this study, I examine the trade based on fishing tools in accordance with the characteristics of the two regions sharing the common lifestyle and fisheries. The kinds of fishing tools can be divided into harpoons and fish hooks. The harpoons can be divided into stone and bone types depending on raw materials, and stationary and separable types on using method, having subdivisions. The fish hooks can be divided into composite, singular, and opposite T-shaped types. These tools are categorized into three based on the aspect to the two regions: high similarity, high difference, and different composition. The fishing tools from the both regions are similar in broader perspective but they are also very different in details at the same time, as a result of selective acceptance of shared information within common concept as tools, rather than trade and exchange of actual tools. The chronology of YNKR fishing tools has three phases. In the I phase, the Yeongnam region is dominated by ground stone artifacts and bone harpoons by influence of the East Sea region and tradition of common knapped stone artifacts. In terms of Northwestern Kyushu region, only knapped fishing tools has been found for the I phase, so it is assumed that the knapped stone artifacts tradition is popular in that region. In the II phase, the diversification of subsistance is conspicuous related to propagation of the early agriculture in the Yeongnam region, and harpoons and hooks are only found from certain sites such as Dongsam-dong and Yokji-do. Unlike the Iphase, the ground stone spear shaped harpoons disappear, and knapped stone spear shaped harpoons become thinner. When it comes to the Northwestern Kyushu region, knapped stone fishing tools has been continuously used in broaden area. In addition, obsidian module harpoon, composite hook, and singular hook are started to be used. The III phase in Yeongnam region, the aspect of fisheries considerably declines according to the social aspect of south of Korean Peninsula such as increased mobility, demolition of villages, and simplification of tools. On the other hand, Northwestern Kyushu region has the largest range of sites as well as shows a dramatic increase in the number of fishing tools. In addition, so-called ‘Northwestern Kyushu fishing culture’ represented by the combination of obsidian module harpoon and composite fish hook is completed. In summary, there is active trade between YNKR, and the routes are multilinear in the I phase. In the II phase, the route becomes unilinear, and it is centered around specific areas such as Dongsam-dong and Yokji-do, which strengthen fisheries. In the III phase, there are few voyages from Yeongnam to Kyushe, while the opposite route is busy. These aspects appear to be related to overall cultural transition, according to the environmental and cultural situation of the two regions, in addition to the relationship with adjacent regions.

Genetic characteristics of Yayoi people in Northwestern Kyushu

Genetic characteristics of Yayoi people in Northwestern Kyushu

藩政確立期の諸問題 : 西北九州諸藩(平戸・大村・佐賀各藩を中心として)

藩政確立期の諸問題 : 西北九州諸藩(平戸・大村・佐賀各藩を中心として)

A57 マグマの時間空間変化から読み取るマントルの進化 : 北西九州北松浦玄武岩を例として

A57 マグマの時間空間変化から読み取るマントルの進化 : 北西九州北松浦玄武岩を例として

A37 開放的な累進的融解によるマグマ生成 : 北西九州、北松浦玄武岩からの制約(火山の物質科学(3),日本火山学会2008年秋季大会)

A37 開放的な累進的融解によるマグマ生成 : 北西九州、北松浦玄武岩からの制約(火山の物質科学(3),日本火山学会2008年秋季大会)

Confirmation of the presence of the Japanese giant flying squirrel Petaurista leucogenys (Rodentia, Sciuridae) in Saga, northwestern Kyushu, Japan

Confirmation of the presence of the Japanese giant flying squirrel <i>Petaurista leucogenys</i> (Rodentia, Sciuridae) in Saga, northwestern Kyushu, Japan