Normal fault at Thingvellir. The boundary between the North American plate on the left-hand side and the Eurasian to the right.| J-STAGE
Reykjavik is a smokeless city. Almost 100% of the electricity and the heating depends upon hydropower and geothermal energy.| J-STAGE
Palagonite ridge formed by subglacial eruption. Langjokull glacier in the background.| J-STAGE
Jokulsarlon lagoon. The Breidamerkurjokull glacier has been retreating since about 1920. The lagoon formed at the glacial front shows a yearly increase.| J-STAGE
The braided course of the Jokulfell downstream from Hofsjokull.| J-STAGE
Valley of Eldgja. The 934-40 Eldgja eruption occurred along a 75 km-long fissure.| J-STAGE
Dettifoss waterfall. The waterfall is 44 m high. The river water is rich in suspended sediments and the waterfall volume is the greatest in Iceland.| J-STAGE
Gullfoss waterfall. The two-step cataract has a total drop of 32 m.| J-STAGE
Earth hummock. Earth hummocks are among the periglacial phenomena. The knoll covered with vegetation is |about 0.5 m high.| J-STAGE
Lakagigar fissure eruption. The 1783-84 Laka- gigar eruption resulted in a great famine, due to which Iceland lost 20% of its population.| J-STAGE
Geyser Strokkur. The geyser erupts at 5-10 minute intervals.| J-STAGE
Basaltic lava field, the Svartshengi geothermal power plant (right), and the Blue Lagoon (left).| J-STAGE

Latest Issue

Journal of Geography (Chigaku Zasshi), 2017 Vol.126 No.6

2017 Vol.126 No.6

Example of Three-dimensional Image Analysis of a Liquefied Boring Core

A: Photograph of the surface of a half-cut core from a site where the 2011 off the Pacific coast of Tohoku Earthquake occurred (cut after CT scanning). The complex bends of the sand dyke are difficult to see. The scale in the longitudinal direction is 23 cm.
B: Soft X-ray image of a slab sample (thickness, 10 mm) taken from the half-cut core. The thick slab obscures the outline of the sand dyke.
C: Two-dimensional CT image (thickness, 0.3 mm) depicting the clear structure of the sand dyke.
D: Segmentation output by the GrowCut algorithm applied to C to extract only the sand dyke body. Details of the GrowCut are described in an article of this issue.
E: 209 two-dimensional segmented images are stacked to show the three-dimensional dyke structure with complex bends and branching.
　A–C, and E are modifications of images of the article (Nakashima and Komatsubara, 2016).

(Yoshito NAKASHIMA)

Reference
Nakashima, Y. and Komatsubara, J. (2016): Seismically induced soft-sediment deformation structures revealed by X-ray computed tomography of boring cores. Tectonophysics, 683, 138–147.

Original Article

Pleistocene Tephrostratigraphy and Underground Sediments
　under the Koriyama Basin at the Southern Part of Northeast Japan

Amao KASAHARA, Takehiko SUZUKI,
Takayuki KAWAI and Toshifumi IMAIZUMI

Journal of Geography (Chigaku Zasshi), 2017, 126(6), 665.

DOI:10.5026/jgeography.126.665

Numerical Modeling of Localized Subsidence Observed in Volcanic Regions Associated
　with the 2011 off the Pacific Coast of Tohoku Earthquake

Kachishige SATO

Journal of Geography (Chigaku Zasshi), 2017, 126(6), 685.

DOI:10.5026/jgeography.126.685

Special Issue: Liquefaction Phenomena in the Downstream Basin of the Tone River, Eastern Kanto Region, Japan from the Viewpoint of Earth Science: Geological and Geo-historical Features of Liquefied Sites

Overview of the Special Issue
　“Liquefaction Phenomena in the Downstream Basin of the Tone River,
　Eastern Kanto Region, Japan from the Viewpoint of Earth Science:
　Geological and Geo-historical Features of Liquefied Sites”

Hiroshi UNE, Taku KOMATSUBARA, Takayuki NAKANO,
Tomonori NAYA and Yoshinori MIYACHI

Journal of Geography (Chigaku Zasshi), 2017, 126(6), 707.

DOI:10.5026/jgeography.126.707

Introduction to the Special Issue
　“Liquefaction Phenomena in the Downstream Basin of the Tone River,
　Eastern Kanto Region, Japan from the Viewpoint of Earth Science:
　Geological and Geo-historical Features of Liquefied Sites”

Hiroshi UNE, Taku KOMATSUBARA, Takayuki NAKANO,
Tomonori NAYA and Yoshinori MIYACHI

Journal of Geography (Chigaku Zasshi), 2017, 126(6), 711.

DOI:10.5026/jgeography.126.711

Relationship between Liquefaction Damage
　and Structure of Lithological Heterogeneity of Holocene Postglacial Deposits
　in the Downstream Basin of the Tone River, Central Japan (Short Article)

Junko KOMATSUBARA, Yoshiro ISHIHARA, Takeshi ISHIHARA,
Osamu KAZAOKA and Kiyohide MIZUNO

Journal of Geography (Chigaku Zasshi), 2017, 126(6), 715.

DOI:10.5026/jgeography.126.715

Relation between Liquefaction Damages
　and Grain Size Distribution of Liquefied Sand Caused
　by the 2011 off the Pacific Coast of Tohoku Earthquake
　in the Hinode Area of Itako City (Original Article)

Atsushi URABE and Taishi YAMAMOTO

Journal of Geography (Chigaku Zasshi), 2017, 126(6), 731.

DOI:10.5026/jgeography.126.731

Estimating of Subsurface Structures around Liquefied Former River Channels
　of the Tone/Kinu River with Geophysical Prospecting (Short Article)

Takayuki NAKANO, Mamoru KOARAI, Toshihiko SUGAI
and Takeshi YOSHIDA

Journal of Geography (Chigaku Zasshi), 2017, 126(6), 749.

DOI:10.5026/jgeography.126.749

Relationship between Liquefied Areas Caused
　by the 2011 off the Pacific Coast of Tohoku Earthquake
　and Time-series Changes in the Distribution of Sand-gravel Pits
　in Kamisu and Kashima Cities (Original Article)

Masafumi AOYAMA and Takushi KOYAMA

Journal of Geography (Chigaku Zasshi), 2017, 126(6), 767.

DOI:10.5026/jgeography.126.767

Introduction to GrowCut, an Image Segmentation Algorithm Applied
　to Liquefaction Images (Letter)

Yoshito NAKASHIMA

Journal of Geography (Chigaku Zasshi), 2017, 126(6), 785.

DOI:10.5026/jgeography.126.785

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