IUGS Geological Heritage Sites についての説明
国際地質科学連合（IUGS）は、世界の 100 万人を超える地球科学者を代表する、121 国が参加する世界最大の科学組織の 1 つです。「ファースト 100」IUGS 地質遺産サイト（The First 100
IUGS Geological Heritage Sites）は、地球とその歴史を理解する上で影響を与えた象徴的な地質学的要素や過程を示す、重要で参照すべき地質学的サイトであり、世界の地球科学者コミュニティが承認したものです。
この取り組みに際して、IUGS の共同事業であり、かつ、ユネスコ世界ジオパーク（UGGp）と共に国際地質科学ジオパーク計画（IGGP）を構成している、地質科学国際研究計画（IGCP）が実施するプロジェクト（IGCP - 731）において、IUGS 地質遺産サイト（Global Geosites）を認定するための基準を整備してきました。40 か国と 10 の国際機関から 250 以上の専門家が、地球科学のさまざまな分野を代表して、サイト選定に参加しました。その結果提案された、56 カ国 181 の候補サイトを、33 人の国際的な専門家が評価し選出しました。
今回、これらのサイトが「ファースト 100」として可視化されることによって、高い科学的価値を持つものとして世界に認識されます。
「ファースト 100」の多くは、国立公園、ジオパーク、自然保護区で十分に保護されていますが、全てではありません。「ファースト 100」の IUGS 地質遺産サイトの認識と可視性によって、それらのさらなる評価、教育資源としての活用、そして最も重要なことはそれらの保存につながることが重要です。
IUGS のウェブサイト: https://iugs-geoheritage.org で完全なリストを参照し、書籍「The First100」をダウンロードしてください
これに関し、スペインのバスクコースト・ユネスコ世界ジオパークで開催された IUGS 60 周年記念行事で100 サイトが紹介され、2022 年 10 月 28 日に認定式典が行われました。
*なお、選定作業の過程でファースト 100 に漏れた地域のうち 49 地域については 2023 年の地質遺産サイトに追加認定されるとされています。
（報告 中田節也 2022 年 11 月 6 日）
添付書類：「ファースト 100」の日本２地域の抜粋と玄武洞、野島断層の認定書

IUGS 60TH
ANNIVERSARYEVENTTHE
FIRSTINIUGSGEOLOGICALHERITAGE
SITESJAPANMore information at www.iugs-geoheritage.com

GENBUDO CAVE

SITE 010

JAPAN

GEOLOGICALPERIOD

Quaternary / Pleistocene

LOCATION

San'in Kaigan Geopark.
Hyogo Prefecture. Japan.
35° 35' 17'' N
134° 48' 18'' E

MAIN
GEOLOGICALINTEREST

History of geosciences

Seiryudo Cave in the Genbudo Cave park, with its regularly but complexly oriented columnar jointing, is anexcellent site for scientific research, education, and sightseeing. (Photo: Noritaka Matsubara).

Geological Description

LOCATION WHERE
GEOMAGNETIC REVERSEDPOLARITY WAS FIRSTPROPOSED THROUGHSTUDYING BASALTS.

Around 100 years ago, Motonori Matuyama
first proposed geomagnetic reversal in
Genbudo. This discovery greatly contributed to the subsequent advancement ofearth science; for example, ocean-floor
paleomagnetic stripes based on magnetic normal and reversed polarity intervals
advanced model of plate tectonics in thelate 1960s (Vine and Mattherws, 1963).

The age of the basalt was determined in
1966, and their geological mapping wascompleted in 1991. Good exposures inGenbudo Park are quarries worked before
the designation of the natural monument.
Hexagonal disks of their columns of basalt were used for river banks, fire walls,and house fences. Such findings are useful for educational purposes.

To Kinosaki

San’ in Kaigan UGGｐTokyo
Kyoto
35°N
Osaka

Ner

Genbudo cave

San’inMa
Maruyi
am n Linag
aw e
ariv

Genbudo and two caves, which are the remnants of digging, where rocks were used for construction
against natural disasters but are now preserved as a monument. (Photo: Noritaka Matsubara).

Matuyama proposed the first geomagnetic reversal polarity approximately 100 years
ago. The 2.58–0.774-Ma period was adopted
as “Matuyama Reversed Chron” in the 1960s(Cox et al., 1964). The Matuyama Reversal
was established as the start of Quaternary(Head et al., 2008).

Koto Bunjiro named the basalt “Genbugan”
in Japanese from Genbudo, whose Chinesecharacters are used also in China. In 1931,
Genbudo Caves were designated as a national natural monument. Since then, they havebeen preserved and managed as educationalsites, accessible only for research.

B’JR

UNESCO Global Geopark

Genbudo is one of the Quaternary Monogenic
Basalt volcanoes in central Japan. The lavaof Genbudo Cave is 1.61-Ma alkaline basalt(Genbudo Research Group, 1991; Kawai and Hirooka, 1966). It exhibits spectacular columnar
jointing reflecting its complex cooling history.
In 1926, Dr. Motonori Matuyama discoveredthat the basalt of Genbudo Cave exhibitedmagnetic polarity opposite to the present
geomagnetic field. This discovery led to therecognition of the presence of a period of theearth’s magnetic field opposite to the present,and in 1929, he proposed “geomagnetic reversal polarity” (Matuyama, 1929). The geomagnetically reversed period, including the age ofGenbudo, was named “Matuyama ReversedChron” in the 1960s, whose start corresponds
to the beginning of Quaternary.

Scientific research and tradition

135°E

A

35°36’

A’B

135°47’B’

A’

Ritsuzan Shibano, a Confucian scholar, visited
Genbudo Cave in 1807 and named it Genbudo
because he compared the outcrop’s irregularly oriented columnar joints to a Chinese legendary animal, Genbu (black tortoise). In 1884,

Mt. Hutami

GenbudoBAkaishi Lava

Kitasuzaku Cave
Seiryudo Cave
Minamisuzaku Cave
Genbudo Cave
Byakko Cave

Genbudo Lava
Information
officeA

Geological Map around the Genbudo Cave Park. Five
caves in the Genbudo Cave Park are the ruins ofquarries.

1km
To Toyooka

Main Outcrops

WC

N

100m

NOJIMA FAULT

SITE 074

JAPAN

GEOLOGICALPERIOD

Quaternary
Modern (1995)

LOCATION

Awaji City, Hyogo
Prefecture, Japan34° 32' 60'' N
134° 56' 16'' E

MAIN
GEOLOGICALINTEREST

Tectonics
Geomorphology andactive geologicalprocesses
Right-lateral displacement of the earthquake fault in the Nojima Fault Preservation Pavilion. (Shigehiro Kato).

Geological Description

Northeastern section of the earthquake fault trench inside the Nojima Fault Preservation Pavilion in theHokudan Earthquake Memorial Park. (Shigehiro Kato)

THE FAULT THATCAUSED THE 1995 KOBE
EARTHQUAKE.

“Earthquake fault” is a surface displacementthat is important evidence of both the earthquake and the resultant disaster. The preservation of earthquake faults is extremely rare
because they are soon flattened by landowners to recover their livelihoods in addition
to the difficulty in conservation techniquesand management. Fortunately, immediately

after the Kobe Earthquake, the Nojima Fault
was preserved for educational and research
purposes, and the topography and damaged
condition of this fault were preserved in thebest way possible (Katoh, 2020). As in Taiwan, the technique and management methods developed here have become the standard for fault conservation.

The Nojima Fault is an active fault that generated the “Hyogo-ken Nambu Earthquake”(Kobe Earthquake) (M7.3), which hit thesouthern part of Hyogo Prefecture, central Japan, on January 17, 1995, killing approximately
6,400 people (Ando et al., 2001; Awata et al.,1996). The fault extends northeastward, intermittently traceable on the surface, for a total
length of approximately 9 km from Hokudan toIchinomiya towns (both now Awaji City) in thenorthern part of Awaji Island. This is a reverse
fault with a right-lateral strike-slip component,
showing the maximum horizontal and verticaldisplacements of 2.1 and 1.2 m, respectively(Lin and Uda, 1996). The Nojima Fault is typically exposed for approximately 185-m long in
Hokudan Town, with approximately four-fifths
of it preserved in the building, Nojima Fault
Preservation Pavilion of Awaji City, which isopen to the public. A trench inside the building

Sketch of the northeasternsection of the earthquake trench
inside the preservation pavilion.

Scientific research and tradition
exhibits the cross section of the fault, whichhas a vertical displacement of 0.2–0.5 m that
uplifted the southeast side with a right-lateral displacement of 0.7–1.5 m (Takemura et al.,1998). The main fault and parallel-extending
bifurcated fault with destroyed paved roads,
displaced ridges, drainage channels, and forest hedges are preserved.

Rupture propagation along the Nojima Fault is
discussed from detailed along-fault distributions of vertical and horizontal displacements.
Based on trenching surveys and analysis of
nearby drilling cores, the fault was reactivated many times during the late Quaternarywith a recurrence interval of approximately
2000 years (Lin and Nishiwaki, 2019).

T H E I N T E R N AT I O N A L U N I O N O F G EO L O G I CA L S C I E N C ES
D U R I N G I TS 6 0 T H A N N I V E R SA RY E V E N T
CERTIFIES THATGenbudo Cave.
JapanH A S B E E N D E S I G N AT E D A N D I N C L U D E D I N T H E L I S T O F

THE FIRST 100 IUGS GEOLOGICAL HERITAGE SITESAn IUGS GeologicalHeritage Site is a key placewith geological elements
and/or processes ofinternational scientific
relevance, used as areference, and/or with asubstantial contribution
to the development ofgeological sciences
through history

In Zumaia, Basque Coast UNESCO Global Geopark 28 / October / 2022

Stanley FinneySecretary General. International Union of Geological Sciences (IUGS)Asier HilarioChair. IUGS-International Commissions on Geoheritage

T H E I N T E R N AT I O N A L U N I O N O F G EO L O G I CA L S C I E N C ESD U R I N G I TS 6 0 T H A N N I V E R SA RY E V E N T
CERTIFIES THATNojima Fault.
JapanH A S B E E N D E S I G N AT E D A N D I N C L U D E D I N T H E L I S T O FTHE FIRST 100 IUGS GEOLOGICAL HERITAGE SITESAn IUGS GeologicalHeritage Site is a key placewith geological elements
and/or processes ofinternational scientific
relevance, used as areference, and/or with asubstantial contribution
to the development ofgeological sciences
through history

In Zumaia, Basque Coast UNESCO Global Geopark 28 / October / 2022

Stanley Finney
Secretary General. International Union of Geological Sciences (IUGS)Asier Hilario
Chair. IUGS-International Commissions on Geoheritage