Bull. Volcanol. Soc. Japan
Vol. /0 (,*++) No. . · /, pp. +,1ῌ+-/Article

Three-dimensional Digital Mapping of the Noboribetsu Geothermal
Field, Kuttara Volcano, Hokkaido, Japan,
using a Helicopter-borne High-resolution Laser Scanner
Yoshihiko GOTOῌ, Satoru MATSUZUKAῌῌ and Seiji KAMEYAMAῌῌ
(Received February 3, ,*++ ; Accepted August ,0, ,*++)
An aerial high-resolution laser-scanner survey was performed in November ,**0 over the Noboribetsu
Geothermal Field on Kuttara Volcano, Hokkaido, Japan. The ,῎,.. km survey area covers the entire geothermal ﬁeld. A three-dimensional digital map, produced from the laser-scanning data, shows detailed topographic
features of the geothermal ﬁeld. Notable features include a cryptodome formed by the intrusion of high-viscosity
magma, a plain that is inferred to have formed by river damming due to growth of the cryptodome, and explosion
craters that are aligned NWῌSE. These features suggest that the geothermal ﬁeld has evolved by complex
volcanic activity and ground deformation involving cryptodome growth, river damming, and phreatic explosions.
The NWῌSE elongation of the cryptodome and the NWῌSE alignment of explosion craters indicate the injectionof magma and hydrothermal ﬂuids along NWῌSE-trending fractures. High-resolution laser-scanner surveys
provide valuable information for understanding the geology of geothermal ﬁelds.
Key words : laser scanner, digital mapping, three dimensions, explosion crater, Noboribetsu Geothermal Field,
Kuttara Volcano+. Introduction
LIDER (light detection and ranging) is a powerfultool for studying the morphological features of volcanoes(e.g., Hunter et al., ,**- ; Chiba et al., ,**1a, ,**1b ;Pesci et al., ,**1). Three-dimensional digital mapping
based on high-resolution laser-scanning data provides
invaluable information on the distribution and morphology of craters, lavas, domes, and pyroclastic deposits, aswell as reworked deposits. Laser-scanner mapping isparticularly useful for surveying topographic features inthickly vegetated areas, for which ῌtree-removing῍ dataﬁltering can be used to reveal the topography of theground surface.
We performed an aerial laser-scanner survey over theNoboribetsu Geothermal Field at Kuttara Volcano,
Hokkaido, Japan, using a high-resolution laser scanner
mounted on a manned helicopter. The Noboribetsu
Geothermal Field is covered with thick vegetation, andthree-dimensional digital mapping based on the laserscanning data provided an excellent tool with which tostudy detailed topographic features of the geothermal
ﬁeld, as a basis for understanding its geology. Thispaper describes the topographic features of the geother῏College of Environmental Technology, Graduate Schoolof Engineering, Muroran Institute of Technology,
Mizumoto-cho ,1ῌ+, Muroran, Hokkaido */*ῌ2/2/, Japan.
῏῏Tanaka Consultant Co., Ltd, Shinkai-cho , ῌ + ῌ - ,mal ﬁeld and discusses the characteristics of volcanic
activity in the ﬁeld.
,. Noboribetsu Geothermal Field
The Noboribetsu Geothermal Field lies in the westernpart of Kuttara Volcano (Fig. +), an andesitic to rhyolitic
composite volcano (elevation, /.3 m above sea level)with a small caldera at its summit (Lake Kuttara).
The volcano evolved over the period 2*ῌ./ ka, involving
early silicic explosive activity and subsequent stratovolcano building associated with caldera collapse at .*ka (Katsui et al., +322 ; Yamagata, +33. ; Moriizumi,+332 ; Moriya, ,**-). The geothermal ﬁeld, which isinferred to have formed after the collapse of the caldera(Katsui et al., +322), is approximately + km wide (NEῌSW) and +./ km long (NWῌSE), and is situated at analtitude of ,**ῌ-1* m. It is one of the major geothermal ﬁelds in Japan.
The geothermal ﬁeld is characterized by a dacitic
cryptodome (Hiyoriyama Cryptodome), a volcanic lake(Oyunuma Lake), and a fumarolic valley (JigokudaniValley) (Fig. +). The Hiyoriyama Cryptodome, in thenorthern part of the geothermal ﬁeld, rises -11 m above
Tomakomai, Hokkaido */*ῌ2/2/, Japan.
Corresponding author : Yoshihiko Gotoe-mail : ygoto@mmm.muroran-it.ac.jp