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

ArticleThree-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 to
study detailed topographic features of the geothermal
ﬁeld, as a basis for understanding its geology. This
paper 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 (Jigokudani
Valley) (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

128

Yoshihiko GOTO, Satoru MATSUZUKA and Seiji KAMEYAMA

Fig. +. Location map of the Noboribetsu Geothermal Field at Kuttara Volcano, Hokkaido, Japan.
The survey area (Fig. -) is shown by the rectangle. The contour interval on the base map is +* m.

sea level and has active fumaroles at its summit.
Oyunuma Lake, in the central part of the geothermal
ﬁeld, is ++/῍,+* m in surface area and is ﬁlled with hot
acidic water. The Jigokudani Valley, in the southernpart of the geothermal ﬁeld, extends for /** m ENEῌWSW and hosts a number of active fumaroles. The
geothermal ﬁeld is widely covered with thick vegetation,
mainly broadleaf trees.
-. Laser-scanner survey
The laser-scanner survey covered the entire Noboribetsu Geothermal Field, encompassing an area extending , km EῌW and ,.. km NῌS (Fig. +). The survey
was carried out by Tanaka Consultant Co. Ltd using a
Develo LISA- instrument (Fig. ,). Under typicalconditions, the scanner is able to measure distances of
up to +*** m with an accuracy of ῌ+* mm (Table +).
The lightweight instrument can be mounted on an airplane, a manned helicopter, or a radio-controlled helicopter. In the present survey, LISA- was mounted ona manned Robinson R.. helicopter (Fig. ,A).
The survey was performed on ,/ November ,**0.
Considerations for setting the date of the survey were(+) the timing of the end of leaf fall to minimize tree
noise, (,) the number of available GPS NAVSTAR
satellites (to minimize positioning error), (-) good
ﬂight conditions, and (.) good ground conditions with-out snowfall. On ,/ November, the broadleaf trees inthe survey area were bare, the weather was ﬁne andcalm, and there was no snow on the ground.
The ﬂight height of the helicopter was ,/*ῌ-** m above
the ground, and the measuring time was +./ h (+* : **ῌ++ : -* AM local time). The position of the helicopter
was recorded at +-s intervals using a Global Positioning
System (GPS) and at *.*+-s intervals using an inertial
measurement unit (IMU). After the ﬂight, the threedimensional ﬂight route was reconstructed from the
GPS and IMU data.
The laser-scanning data were initially cleaned toremove noise and then ﬁltered to produce a digitalterrain model (DTM), which shows the bare groundsurface. As part of the ﬁltering process, trees andbuildings were carefully removed using the application
TerraScan (Terrasolid Co. Ltd). Both automatic andhandpicking methods were used in this process to avoid
removing necessary information. After ﬁltering, a triangulated irregular network (TIN) was produced fromthe ground data. In turn, a three-dimensional digital
map was produced from the TIN, using the Red Relief
Image Map technique (Chiba et al., ,**1a) (Fig. -).
The colors in the map express the angle of inclination of
the ground surface (expressed by the saturation of red,
whereby steep slopes appear highly saturated) and theopening ratio (Yokoyama et al., +333) of the groundThree-dimensional Digital Mapping of the Noboribetsu Geothermal Field, Kuttara Volcano, Hokkaido, Japan, using a Helicopter-borne High-resolution Laser Scanner

129

Table +. Speciﬁcations of the laser scanner, Develo
LISA-. The laser class is based on the safetyclassiﬁcation of laser devices according to Japan
Industrial Standard (JIS) C02*,. Note that beam
divergence of the LISA- is *.,/ mrad (i.e., abeam diameter of ,/ mm at a distance of +** m).

Fig. ,. (A) Photograph of the LISA- instrument
mounted on a manned helicopter. (B) Close-up
photograph of the LISA- instrument.

surface (expressed by the brightness of red, whereby
ridges appear bright red and valleys appear dark red).
.. Results
Figure - shows the obtained three-dimensional digital
map of the Noboribetsu Geothermal Field ; an annotatedversion is shown in Figure .. The notable topographic
features in the map are an elongate cryptodome oriented
NW῍SE (Hiyoriyama Cryptodome), a plain locatednortheast of the cryptodome (Hiyoriyama Plain), andexplosion craters aligned NW῍SE (Fig. .). These features and their interpretations are described in detail in
the following sections.
.ῌ+ Hiyoriyama Cryptodome
The Hiyoriyama Cryptodome is elongate NW῍SE
and ranges in diameter from -/* to //* m (Fig. .). It
rises +-* m above the surrounding area, with its highest
point being -11 m above sea level. Figure /A and /Bshows bird’s eye (oblique), three-dimensional images of
the cryptodome from di#erent viewpoints. The cryptodome has a pyramidal form (Fig. /A), suggesting it
formed by the intrusion of high-viscosity magma. The
cryptodome consists of dacite containing 1* wt.ῌ SiO,
(Goto and Danhara, ,*++), which is consistent with its

pyramidal form. The surface of the cryptodome ismoderately eroded (Fig. /A), indicating a relatively old
age of formation. Field surveys revealed that the surface of the cryptodome is covered with tall trees andshort bamboo forest. The cryptodome has been dated
as +/ῌ. ka and +.ῌ. ka by the ﬁssion-track method(Goto and Danhara, ,*++), which is consistent with themoderately eroded topography and thick vegetation
cover. The NW῍SE elongation of the cryptodome (Fig.
.) suggests that the feeder dyke beneath the dome alsostrikes NW῍SE.
On the northern slope of the dome, a curved ridge
extends for more than -** m (Fig. /B). The ridge
rises to --*῍-.* m above sea level and protrudes /῍+* mabove the slope, forming a V-shaped valley on its uphillside. The ridge is hidden by thick vegetation and is
identiﬁed here for the ﬁrst time. Field surveys revealed
that the ridge and the V-shaped valley form a conspicuous step on the slope, although they are covered withtall trees and short bamboo forest. The ridge may haveformed by the fracturing and detachment of surﬁcial
sediment, or the northward displacement of the sediment during growth of the cryptodome.
The cryptodome has several explosion craters on its
surface (Figs. . and /A). These craters are inferred tohave formed by phreatic explosions that occurred after
emplacement of the dome. The explosion crater at thesummit (the Hiyoriyama Summit Crater ; no. - in Fig.
/A) is elongate NW῍SE and ranges in diameter from .*to 3/ m. The crater retains its primary morphologicalfeatures, including the crater rim and wall, and it contains active fumaroles. Field surveys (Goto et al.,,*++) found that a phreatic deposit erupted from thecrater overlies the Us-b tephra (Yokoyama et al., +31- ;Machida and Arai, ,**-), which was emplaced in AD+00-. The Hiyoriyama Summit Crater is thus inferred

130

Yoshihiko GOTO, Satoru MATSUZUKA and Seiji KAMEYAMA

Fig. -. Three-dimensional digital map of the Noboribetsu Geothermal Field, expressed using the Red Relief Image
Map technique.

to have formed after AD +00-. The well-preserved
morphology of the crater is consistent with the stratigraphy of the deposit. Three explosion craters on theslope of the dome, named Hiyoriyama North, Hiyoriyama Southwest, and Hiyoriyama South (nos. ., /, and0, respectively, in Fig. /A and Table ,), are circular inplan view and have diameters of -/, ++/, and 1/ m,
respectively. These craters are more strongly eroded
than the Hiyoriyama Summit Crater, possibly indicating
they are relatively old. Field surveys revealed that thesecraters contain no active fumaroles.

Three-dimensional Digital Mapping of the Noboribetsu Geothermal Field, Kuttara Volcano, Hokkaido, Japan, using a Helicopter-borne High-resolution Laser Scanner131

Fig. .. Interpretation of the map shown in Fig. -. The names and dimensions of the numbered craters are listed inTable ,.

.ῌ, Hiyoriyama Plain
The Hiyoriyama Plain occurs northeast of the Hiyoriyama Cryptodome (Figs. . and /B). The plain issemi-rectangular in plan view, being -** m (NWῌSE)ῌ
2** m (NEῌSW) in size, and is located at -** m above
sea level. Its ﬂat topography is conspicuous in therugged terrain of the region. East of the plain, theriver system trends EῌW, whereas within the plain the
pre-existing river system is buried by sediment (Figs. and .). The southwestern termination of the plain issharply deﬁned by the Hiyoriyama Cryptodome (Fig. /B). Field surveys suggest that the plain is a dried

132

Yoshihiko GOTO, Satoru MATSUZUKA and Seiji KAMEYAMA

Fig. /. (A) Bird’s eye (oblique), three-dimensional image of the Hiyoriyama Cryptodome viewed from the south.
Crater numbers correspond to those in Fig. . and Table ,. The Hiyoriyama Cryptodome has explosion craters
at its summit (crater -) and on its slope (craters ., /, and 0). (B) Bird’s eye (oblique), three-dimensional
image of the Hiyoriyama Cryptodome and surrounding area viewed from the north. The cryptodome has acurved ridge on its northern slope. Hiyoriyama Plain is conspicuous in the rugged terrain of the region, and isinferred to have formed by damming of a river due to growth of the Hiyoriyama Cryptodome. Crater numbers
correspond to those in Fig. . and Table ,.

wetland which is now covered by short bamboo andgrasses. There are no lakes or ponds upon the plain.
The Hiyoriyama Plain buries the pre-existing riverinﬂuenced topography (Figs. . and /B), suggesting that
it formed by damming of the river and deposition of
sediment behind the dam. The river system of the surrounding area indicates that the sediments were derived
from rivers draining to the west. The western marginof the plain is marked by the Hiyoriyama Cryptodome,
suggesting that formation of the cryptodome resulted indamming of the river, and that the dammed lake became
ﬁlled with sediment. Drilling in the western part of the
Hiyoriyama Plain (unpublished data) has revealed a +/m-thick layer of peat beneath the plain. The dammingof a river due to cryptodome growth has also been reported for the +3.. eruptions at Usu volcano, Hokkaido,
Japan, where the Shinzan-numa Pond formed due togrowth of the Showa-shinzan Cryptodome (Mimatsu,+33/).
.ῌ- Explosion craters
At least +1 explosion craters are identiﬁed from themap of the Noboribetsu Geothermal Field (Fig. .),recognized by their conical morphology, circular or
semicircular outline, and ﬂat bottom. The explosion
craters are ,/ῌ,+* m in diameter and /ῌ/* m deep.
The names and dimensions of the craters are listed inTable ,. Most show well-preserved primary morphology, although some are eroded. The craters are dis-Three-dimensional Digital Mapping of the Noboribetsu Geothermal Field, Kuttara Volcano, Hokkaido, Japan, using a Helicopter-borne High-resolution Laser Scanner133

Table ,. Topographic data of explosion craters in the Noboribetsu Geothermal Field.
Locations are shown in Fig. ..

Fig. 0. Photograph of a newly identiﬁed explosion
crater (Kitanuma) in the northwestern part of
the Noboribetsu Geothermal Field (crater , inFig. .). The crater is /*ῌ// m across ; the pond
within the crater is ,. m across and , m deep.

tributed in a NWῌSE-trending zone that is /** m wide
and +,/** m long, which also includes the Hiyoriyama
Cryptodome (Fig. .).
The three-dimensional map is useful in identifying
explosion craters hidden by thick vegetation ; indeed,
several explosion craters were newly found by thismapping survey. For example, Kitanuma Crater (/*ῌ// m across ; no. , in Fig. .) is hidden by tall trees andthick bamboo but is obvious on the three-dimensionalmap (Fig. -). A ﬁeld survey revealed that the cratercontains a pond with fresh water (Fig. 0). Higashizawa
Crater (+-/ m across ; no. +/ in Fig. .) is also hidden by

thick vegetation but is easily identiﬁed on the threedimensional map (Fig. -).
The explosion craters in the Noboribetsu Geothermal
Field are relatively small (diameters of ,/ῌ,+* m ; Table,), suggesting that most of them formed by phreatic
explosions. Based on the degree of erosion, most of thecraters are inferred to have formed during the past
several thousand years. The craters show varying degrees
of erosion, indicating they formed at di#erent times,
although the timing of crater formation remains unknown. The craters are aligned NWῌSE (Fig. .) andare distributed in a zone that is /** m wide and +,/** mlong, suggesting that phreatic explosions during the past
several thousand years have been conﬁned to within thiszone. The Hiyoriyama Cryptodome is also elongate
NEῌSW, indicating that ascending magma followed
underground fractures with this orientation. We inferthat the common alignment of the explosion craters andthe cryptodome reﬂects the upwelling of magma andhydrothermal ﬂuids along subsurface fractures with thisorientation. The orientation of the fractures may
reﬂect the tectonic stress ﬁeld related to the northwestern movement of the Paciﬁc Plate (see also Jackson etal., +31/ ; Nakamura, +311 ; Watanabe, +33-).
/. Conclusion
The Noboribetsu Geothermal Field formed as a resultof complex ground deformation involving growth of the
Hiyoriyama Cryptodome and formation of the Hiyoriyama Plain by river damming, and a number of explosion craters formed by phreatic eruptions. The commonalignment of the explosion craters and the Hiyoriyama
Cryptodome suggests the ascent of magma/ﬂuid along

134

Yoshihiko GOTO, Satoru MATSUZUKA and Seiji KAMEYAMANWῌSE-trending fractures. Three-dimensional laserscanner surveys provide valuable geological information
for understanding the geology of geothermal ﬁelds.
Acknowledgements
This research was sponsored by the Ministry of Education, Culture, Sports, Science and Technology ofJapan (MEXT), and was supported ﬁnancially by the
Hokkaido Bureau of Economy, Trade and Industry(METI), and the Muroran Institute of Technology.
We thank T. Nitta and M. Kiriki (Tanaka Consultant
Co., Ltd) for assistance with the mapping survey, T.
Chiba (Asia Air Survey Co., Ltd) for constructive
suggestions in interpreting the map, N. Yabuki (MuroranInstitute of Technology) for providing data on measurement accuracy, and A. Mogaki and Y. Oka (MuroranInstitute of Technology) for help in the ﬁeld. We are
grateful to Y. Ishizaki (University of Toyama) and an
anonymous referee for reviewing the manuscript. T.
Watanabe (University of Toyama) is thanked for editing the manuscript.
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