Kitamura et al. Progress in Earth and Planetary Science (2017) 4:30
DOI 10.1186/s40645-017-0146-5

Progress in Earth andPlanetary Science

RESEARCH ARTICLE

Open Access

Late Holocene uplift of the Izu Islands on
the northern Zenisu Ridge off Central
Japan
Akihisa Kitamura1,2*, Takafumi Imai1, Yuta Mitsui1,2, Mami Ito1, Yosuke Miyairi3, Yusuke Yokoyama3
and Yuki Tokuda4

Abstract
To clarify the Holocene uplift history of the Izu Islands, Japan, we analyze the elevations and 14C ages of emerged
sessile assemblages measured by accelerator mass spectrometry (AMS) on the islands of Niijima, Jinaijima, Shikinejima,
and Kouzushima, on the northern Zenisu Ridge. The results suggest that uplift events took place after AD 1950 (uplift
event 1), during AD 786–1891 (uplift event 2), during AD 600–1165 (uplift event 3), and during AD 161–686 (uplift
event 4), although uplift events 3 and 4 are identified only at Kouzushima. The minimum amount of uplift wasestimated to be 0.4–0.9 m in uplift event 1, 2.4–2.7 m in uplift event 2, 3.6 m in uplift event 3, and 3.3–8.1 m in uplift
event 4. These events could have been caused by volcanic activity or strong earthquakes. There also remains thepossibility that uplift event 2 was caused by the AD 1498 Meio earthquake; in contrast to the previous interpretation,
the ages of uplift events are significantly older than the earthquake, based on conventional (non-AMS) methods.
Keywords: Emerged marine sessile assemblage, 14C date, Holocene, Niijima, Shikinejima, Kouzushima

Introduction
Fukutomi (1935, 1938) discovered emerged sessile assemblages on Shikinejima and Jinaijima within the Izu
Islands and in southern Izu Peninsula, Central Japan(Figs. 1 and 2). He suggested that these assemblages provided evidence of coseismic uplift associated with the AD
1703 great Kanto (Genroku) earthquake (Fig. 1), although
the ages of the assemblages were not obtained. On theother hand, Hatori (1975) and Aida (1981) interpreted
the same assemblages as evidence of the AD 1498 Meio
earthquake (M 8.2–8.4) (Fig. 1). These authors suggested
that the tsunami believed to have been associated with
the Meio earthquake affected coastal regions from Kii
Peninsula to Boso Peninsula, Central Japan (Fig. 1b) andhypothesized that the rupture area included the westernand eastern Tōnankai segments (C and D in Fig. 1a, respectively) and the area south of Izu Peninsula.
* Correspondence: kitamura.akihisa@shizuoka.ac.jp1
Institute of Geosciences, Shizuoka University, 836 Oya, Suruga-ku, Shizuoka
422-8529, Japan
2
Center for Integrated Research and Education of Natural Hazards, Shizuoka
University, 836 Oya, Suruga-ku, Shizuoka 422-8529, Japan
Full list of author information is available at the end of the article

Ota et al. (1983, 1986) determined the 14C ages of
emerged assemblages from the southern coast of Izu
Peninsula and Shikinejima (Fig. 2; Table 1), and demonstrated that the ages obtained were inconsistent
with the hypotheses of Fukutomi (1935, 1938), Hatori(1975), and Aida (1981). However, these ages were
not calibrated. Kitamura et al. (2016) examined thefaunal compositions and accelerator mass spectrometry (AMS) 14C ages of emerged sessile assemblages
in the southern part of Izu Peninsula and concluded
that coseismic uplift occurred in the periods 1256–
950 BC, 1000–1270 AD, 1430–1660 AD, and 1506–
1815 AD. Kitamura et al. (2015) found no evidence of
Holocene coseismic uplift at Mikomotojima, a small island located 10 km off the coast of Shimoda and inferredthat the source fault for the uplift events was a reverse
fault located ~ 3 km offshore from southern Izu Peninsula(Fig. 1c). On the other hand, AMS 14C ages have yet to be
determined for the emerged sessile assemblages on Shikinejima. In addition, we know of no published studies of
emerged sessile assemblages on Niijima or Kouzushima.
Thus, the present study examines Holocene crustal movements on the islands of Shikinejima, Niijima, and© The Author(s). 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, andreproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made.

Kitamura et al. Progress in Earth and Planetary Science (2017) 4:30

aPage 2 of 17

138°E

34°N

Eurasia Plate
Kyushu32°N

NorthAmericanPlate
Izu Pen.

HonshuShikoku
Surugatrough

n.

A

Z

N

B

D

C

E

Pe

Bo

2

IM

Nankai Troughso

1

Philippine Sea Plate
132°E

Z

A

B

C

D

E

1

2

Year
600

684 Hakuho
800
887 Ninna
1000
1096 Eicho-Tokai
1099 Kowa
1361 Shohei-Tokai
1361 Shohei-Nankai
1498 Meio
1605 Keicho

1200
1293 Einin Kanto
1400
1600
1703 Genroku Kanto
1800

tsunami earthquake (?)

1707 Hoei
1854 Ansei-Tokai
1854 Ansei-Nankai
1944 Showa-Tonankai
1946 Showa-Nankai

1923 Taisho Kanto
2000
certain spatial extents
less certain spatial extents
possible spatial extents

138°E

Maisakan.

Kii

Honshu N

Kyoto

b
Pe

Kumano
4-5

Ise
6-8

Yaizu
6-8
Kamakura
8-10

6-8

SurugatroughNiijimaKouzushima

SagamitroughFig. 3a-cn.

Atsumi5-6

c Minami Izu ShimodaShikinejimasoNishina5

Pe

Bo

Kominato
4-5

a

ad

u-n

sh
En
ShimodaAD 1498
Kouzushima

NiijimaMiyakejima

fault
Mikomotojima

Miyakejima
Zenisu Ridge
Nankai trough34°N

Fig. 1 a Spatio-temporal distribution of great earthquakes along the Nankai, Suruga, and Sagami troughs (Ando 1975; Ishibashi and Satake 1998; Shishikura2014). Individual fault segments are labeled A–E and Z; 1 indicates the Sagami Bay segment and 2 denotes the South Boso segment. The boundary of theIzu microplate (IM) is after Nishimura et al. (2007). b Distribution of inundation heights for the Meio earthquake, as determined by Hatori (1975). The
hatched area indicates the source area of the Meio earthquake (Hatori 1975). c Map of the study area and Zenisu Ridge. The submarine fault between
Shimoda and Mikomotojima is after Kitamura et al. (2015)

Kouzushima, using elevation data and AMS 14C dating of
emerged marine sessile assemblages.
Study area

Niijima, Jinaijima, Shikinejima, and Kouzushima arelocated along the northern part of the Zenisu Ridgeon the northern Philippine Sea Plate (Fig. 1). The
Zenisu Ridge is a topographic high composed ofoceanic crust (Le Pichon et al. 1987; Chamot-Rookeand Le Pichon 1989; Ishihara 1989; Lallemant et al.

1989; Nakanishi et al. 1994; Fig. 1). Using regional
kinematic models, Mazzotti et al. (1999, 2001) examined the movement of crustal blocks around Central
Japan and identified three blocks: the Philippine Sea
Plate, Central Japan, and the Zenisu–West Izu block.
Sagiya (1999) and Nishimura et al. (2007) refer to the
Zenisu–West Izu block as the Izu microplate (Fig. 1).
A subduction thrust occurs offshore from the Tokai
area along the southern edge of the microplate(Nakanishi et al. 1994). The eastern boundary of theKitamura et al. Progress in Earth and Planetary Science (2017) 4:30

Page 3 of 17

N

ShimodaKakizaki

Iritahama
Ohama

1 km

N

GPS stations

N

Jinaijima

Kozushima 2

Niijima

K1
J1
N1

Kouzushima
K2
K3

K4

TenjosanvolcanoTide-gauge
stationKozushima 1

1 km

Mukai Yama
volcanoS1/Shikinejima 1
S2
S3
S5

Niijima

Shikinejima
S4Shikinejima 3
S6/Shikinejima 2

1 km

Fig. 2 Locality map of field sites on Shimoda, Niijima, Jinaijima, Shikinejima, and Kouzushima, showing sampling sites investigated by Ota et al.
(1983, 1986). The base map is from the 1:200,000 topographic maps “Shimoda,” “Mikomojima,” “Niijima,” and “Kouzushima” published by the
Geospatial Authority of Japan. Red dots indicate GPS stations

microplate consists of a sinistral strike-slip fault zone
(Mazzotti et al. 1999, 2001) that is located less than
10 km west of Shikinejima (Nishimura et al. 2007).
Niijima, Jinaijima, Shikinejima, and Kouzushima consist mainly of Quaternary volcanic rocks (Isshiki 1987).
Historical documents reveal that Mukaiyama volcano on
Niijima and Tenjosan volcano on Kouzushima (Fig. 2)
erupted in AD 886 and AD 838, respectively (Isshiki
Table 1 14C dates reported by Ota et al. (1983, 1986). Area andsampling points are shown in Fig. 2
Area/sampling
pointsMaterials

14
C age(years BP)

Sample height
(m)

Ohama

Chthamalus sp.

2650 ± 80

2.3–2.7

Ohama

Saccostrea echinata 2830 ± 90

2.3–2.7

Ohama

Saccostrea echinata 670 ± 75

1.1

Ohama

Saccostrea echinata 645 ± 80

0.9

Iritahama

Tetraclitella chinensi 950 ± 90

1.45–2.15

Kakizaki

Saccostrea echinata 1280 ± 75

1.6

Kakizaki

Saccostrea echinata 1540 ± 65

1.6

Shikinejima 1

Tetraclitella chinensi 1980 ± 130 3.2–3.6

Shikinejima 1

Megabalanus rosa

Shikinejima 1

Tetraclitella chinensi 1350 ± 100 2.6

Shikinejima 1

Saccostrea kegaki

2540 ± 290 2.6

Shikinejima 2

Tetraclita japonica

1010 ± 300 4.2

Shikinejima 3

Tetraclitella chinensi 1530 ± 100 3.9–5.1

1830 ± 130 3.0–3.1

1987). Togashi (1984) suggested that volcanic activity
also occurred about 230 years before the AD 838
Kouzushima eruption.
Earthquakes in AD 1890 (M 6.8) and 1936 (M 6.3)
damaged Shikinejima and Niijima, respectively(Hagiwara and Omote 1936; Honda 1938; Hamada
2001), with epicenters located approximately 14 km and
1 km south of Niijima Island, respectively (Hamada
2001; Fig. 3). The focal mechanisms of both earthquakes(Honda 1938) indicate strike-slip motion (Fig. 3d).
Recent crustal movements in the study area havebeen inferred from tide gauge and Global Positioning
System (GPS) data. Tide-gauge data indicate about
0.9 m of uplift of Kouzushima Island between 1990 and2014 (Coastal Movements Data Center, 2016; Fig. 4a).
GPS time-series data of the F3 solution (Nakagawa et
al. 2009) of GEONET, provided by the Geospatial Information Authority of Japan, reveal that Shikinejima andNiijima are being uplifted at a mean rate of 1.0 cm/year
since 1998 (Fig. 4b). This uplift is related to a pressuresource located beneath northeastern Kouzushima(Kimata et al. 2000) and dike intrusion associated with
the AD 2000 eruption of Miyakejima volcano, southeastof Kouzushima (Fig. 2) (Murakami et al. 2001;
Nishimura et al. 2001; Yamaoka et al. 2005).
The coastlines in the study area are characterized by awave-dominated and microtidal regime, with a maximum tidal range of 1.6 m during spring tides. In thisKitamura et al. Progress in Earth and Planetary Science (2017) 4:30

Page 4 of 17ab
Shikinejima

Kozushima

1890/04/16
M 6.8

1900/11/10
M 6.4

1900/11/05
M 6.6
50 km

M
7.0

1982/12/28
M 6.4

1991/09/03
M 6.3
50 km

5.5

2000/07/09
M 6.1

2000/07/15
M 6.3

1983/10/03
M 6.2

1956/08/13
M 6.3

1956/12/22
M 6.0

6.0

1 January 1885 to 31 December 1925c

1957/11/11
M 6.0

1936/12/27
M 6.3

Miyakejima
1908/05/13
M 6.0

1986/11/11
M 6.0

1944/12/09
M 6.3

Niijima

1885/09/26
M 6.8

1956/12/23
M 6.0

1 January 1926 to 31 December 1999

d
135°E

2000/08/18
M 6.1
2000/07/01
M 6.5

1974/06/27
M 6.1

138°E

141°E

Honshu36°N

2013/04/17
M 6.2
34°N
2000/07/30
M 6.0
50 km

2000/07/30
M 6.5

After 1 January 2000

Fig. 3 a, b Epicentral locations of significant earthquakes in the study area (Hamada 2001). c Epicentral locations of significant earthquakes in the
study area based on the hypocenter catalog of the Japan Meteorological Agency. d P wave first motions of the 27 December 1936 earthquake(Honda, 1938) with possible slip directions indicated by black arrowsabFig. 4 a Mean relative sea-level changes since 1964 measured bytide gauges at Minami Izu and Kouzushima (Coastal Movements
Data Center, 2016). b Relative vertical displacement at GPS
stations during the period 1 January 1998 and 5 November 2016
at Niijima, Shikinejima, and Kouzushima (GEONET F3 solution
based on Nakagawa et al. (2009))

study, the intertidal zone ranges between − 0.8 and
0.8 m above mean sea level (amsl).

Methods/Experimental
This study examines emerged marine sessile assemblages at one site on Niijima, one site on Jinaijima, sixsites on Shikinejima, and four sites on Kouzushima(Fig. 2). At each site, we collected several samples ofwell-preserved barnacles, bivalves, Serpulidae, andcorals. Before the specimens were identified, each wascleaned with a micro-knife and organic matter was removed using hydrochloric acid. The coral samples wereanalyzed by X-ray photography and X-ray diffraction.
Radiocarbon dating was performed by accelerator mass
spectrometry (AMS) at the University of Tokyo, Japan(Yokoyama et al. 2016). Radiocarbon ages were thentranslated into calendar time scales using the program
OxCal 4.3 (Bronk Ramsey 1995; Bronk Ramsey and Lee2013), based on comparisons with Marine 13 data
(Reimer et al. 2013). A local correction ofΔR = 109 ± 60
calculated for Shimoda, 42 km northwest of Shikinejima (Yoneda et al. 2000), was applied to all data. We
also observed the upper limit of living hermatypic coral,
Saccostrea kegaki and Crassostrea gigas oysters, Tetraclitella chinensis barnacles, and Pomatoleios kraussii
tubeworms where we collected the emerged specimens.
Since these species occur in high densities, reliable data
were easily obtained.

Kitamura et al. Progress in Earth and Planetary Science (2017) 4:30

Page 5 of 17

Results

Shikinejima

Site descriptions and 14C dating
Niijima

Site S1 is a cave located in a cliff south of Tomari Port
(Figs. 2 and 7a). The cave is 1 m wide, 10 m high, and 4 mlong. Inside the cave, we collected many well-preserved
individual samples of the barnacle Tetraclitella chinensis(Fig. 7b) and in situ samples of the bivalve Cardita leana
at elevations of 2.6–4.0 m amsl (Fig. 7c). 14C dates of all
specimens range from AD 1006 to 1891 (Table 2). Ota etal. (1983) previously collected uplifted sessile assemblages
from this site and obtained non-calibrated 14C ages of1980 ± 130 years BP and 1350 ± 100 years BP for specimens found at elevations of 3.2–3.6 and 2.6 m amsl, respectively (Table 1). We observed that the upper limit ofliving T. chinensis is about + 0.8 m amsl.
Site S2 is located on bedrock on the east side of Oura
Bay, at about + 3.0 m amsl (Fig. 2). The 14C age of wellpreserved C. leana is AD 988–1268 (Table 2).
Site S3 is located on bedrock on the west side of Oura
Bay, at about + 2.3 m amsl (Fig. 2). This site yielded
many well-preserved examples of T. chinensis thatyielded 14C dates in the range AD 1216–1505.
Site S4 is located on bedrock on the east side of Nakanoura Bay, at approximately − 0.1 m amsl (Figs. 2 and 8a).
This site yielded three in situ colonial zooxanthellate scleractinian corals of Cyphastrea serailia (Fig. 8b), which were100% aragonite and therefore not susceptible to diagenesis.

At site N1, we collected in situ specimens of abraded
Saccostrea kegaki at 0.0–0.7 m amsl and in situ samples of fresh Crassostrea gigas at 0.3–0.9 m amsl
(Figs. 2 and 5). We observed the burial of these specimens by sand on 22 September 2014. Although two
specimens of S. kegaki fall within the age range ofAD 1816 to present, all other samples represent modern specimens (Table 2). The upper limit of living S.
kegaki is + 0.4 m amsl, while living specimens of C.
gigas could not be found.
Jinaijima

Jinaijima is a small island located 2 km west of
Niijima Island (Fig. 2). We collected encrusting
masses of Pomatoleios kraussii tubeworms at 0.6 m
amsl at site J1, which is located on bedrock on theeast side of the Island (Figs. 2 and 6). The encrusting
masses are up to 4 cm thick and lack any observable
layered structure. 14C dating of the surface (J11) andinnermost part (J12) of the masses yields ranges ofAD 1724 to present and AD 1727 to present, respectively (Table 2). Encrusting masses of living P. kraussii
could not be found.

a

b

b

c

c

23 March 2015 (5:17 pm on Japan Time)de

22 September 2014
(2:20 pm on Japan Time)d

24 September 2014 (7:20 pm on Japan Time)

e

2 cm

sea level (correspond to meanhigh tide)
Fig. 5 Photographs of a the study area at site N1 in Niijima, b the sampling point at which S. kegaki was collected, c the sampling point at which
C. gigas was collected, d S. kegaki. (arrows indicate individual examples), and e C. gigas (arrows indicate individual examples)Kitamura et al. Progress in Earth and Planetary Science (2017) 4:30

Page 6 of 17

Table 2 Results of 14C dating in the present study
Samplename

Locality

Site Laboratory
number(YAUT-)

Coordinates(lat/long)

Height(m)

Uppergrowth
limit (m)Materials

Conventional
14
C age (years
BP)

Calibratedage (2σ)Groups Total
minimum
uplift (m)N1

Niijima

N1

14905

34.21499°
139.14331°

0.7

0.4 (0.8)

Saccostrea
kegaki407 ± 32

Cal AD
1816–
1950

A

0.3 (− 0.1)

N2

Niijima

N1

14906

34.21499°
139.14331°

0.6

0.4 (0.8)

Saccostrea
kegaki294 ± 32

Cal AD
1847–
1950

A

0.2 (− 0.2)

N3

Niijima

N1

14907

34.21499°
139.14331°

0.6

0.4 (0.8)

Saccostrea
kegaki− 70 ± 37

Cal AD
1885–
1950

A

0.2 (− 0.3)

N4

Niijima

N1

14908

34.21499°
139.14331°

0.5

0.4 (0.8)

Saccostrea
kegaki− 387 ± 34

ModernA

0.1 (− 0.3)

N5

Niijima

N1

14909

34.21499°
139.14331°

0.3

0.4 (0.8)

Saccostrea
kegaki− 686 ± 44

ModernA− 0.1 (− 0.5)

N6

Niijima

N1

14910

34.21499°
139.14331°

0.3

0.4 (0.8)

Saccostrea
kegaki− 687 ± 46

ModernA− 0.1 (− 0.5)

N7

Niijima

N1

14911

34.21499°
139.14331°

0.2

0.4 (0.8)

Saccostrea
kegaki− 595 ± 34

ModernA− 0.2 (− 0.6)

N8

Niijima

N1

14912

34.21499°
139.14331°

0.1

0.4 (0.8)

Saccostrea
kegaki− 720 ± 48

ModernA− 0.3 (− 0.7)

N9

NiijimaN1

14913

34.21499°
139.14331°

0.1

0.4 (0.8)

Saccostrea
kegaki− 789 ± 54

ModernA− 0.3 (− 0.7)

N10

Niijima

N1

14917

34.21499°
139.14331°

0.1

0.4 (0.8)

Saccostrea
kegaki− 815 ± 56

ModernA− 0.3 (− 0.7)

N11

Niijima

N1

14918

34.21499°
139.14331°

0.9

0.4 (0.8)

Crassostrea
gigas− 1157 ± 64

ModernA

0.5 (0.1)

N12

Niijima

N1

14919

34.21499°
139.14331°

0.9

0.4 (0.8)

Crassostrea
gigas− 1088 ± 42

ModernA

0.5 (0.1)

N13

Niijima

N1

14920

34.21499°
139.14331°

0.9

0.4 (0.8)

Crassostrea
gigas− 1151 ± 41

ModernA

0.5 (0.1)

N14

Niijima

N1

14921

34.21499°
139.14331°

0.9

0.4 (0.8)

Crassostrea
gigas− 1171 ± 46

ModernA

0.5 (0.1)

N15

Niijima

N1

14922

34.21499°
139.14331°

0.7

0.4 (0.8)

Crassostrea
gigas− 1209 ± 57

ModernA

0.3 (− 0.1)

J11

Jinaijima

J1

18537

34.22027°
139.13431°

0.6

0.2

Pomatoleios
kraussii482 ± 43

Cal AD
1724–
1950

A

0.4

J12

Jinaijima

J1

18538

34.22027°
139.13431°

0.6

0.2

Pomatoleios
kraussii459 ± 35

Cal AD
1726–
1950

A

0.4

TMR1

Shikinejima S1

9905

34.20119°139.12376°

4

0.8

Tetraclitellachinensis1243 ± 29

Cal AD
1139–
1391

B

3.2

TMR2

Shikinejima S1

14923

34.20119°139.12376°

4

0.8

Tetraclitellachinensis

955 ± 64

Cal AD
1335–
1650

B

3.2

TMR3

Shikinejima S1

9906

34.20119°139.12376°

3.8

0.8

Tetraclitellachinensis

1270 ± 35

Cal AD
1085–
1333

B

3

TMR4

Shikinejima S1

14924

34.20119°139.12376°

3.8

0.8

Tetraclitellachinensis1006 ± 60

Cal AD
1302–
1615

B

3

TMR5

Shikinejima S1

9907

34.20119°139.12376°

3.6

0.8

Tetraclitellachinensis

859 ± 43

Cal AD
1460–
1670

B

2.8

Kitamura et al. Progress in Earth and Planetary Science (2017) 4:30

Page 7 of 17

Table 2 Results of 14C dating in the present study (Continued)
Coordinates(lat/long)

Height(m)

Uppergrowth
limit (m)Materials

Conventional
14
C age (years
BP)

Calibratedage (2σ)Groups Total
minimum
uplift (m)14925

34.20119°139.12376°

3.6

0.8

Tetraclitellachinensis1265 ± 37

Cal AD
1069–
1380

B

2.8

Shikinejima S1

9908

34.20119°139.12376°

3.4

0.8

Tetraclitellachinensis1051 ± 41

Cal AD
1308–
1487

B

2.6

TMR8

Shikinejima S1

14926

34.20119°139.12376°

3.4

0.8

Tetraclitellachinensis

837 ± 70

Cal AD
1431–
1804

B

2.6

TMR9

Shikinejima S1

9909

34.20119°139.12376°

3.2

0.8

Tetraclitellachinensis

844 ± 34

Cal AD
1468–
1678

B

2.4

TMR10

Shikinejima S1

14930

34.20119°139.12376°

3.2

0.8

Tetraclitellachinensis1319 ± 36

Cal AD
1048–
1305

B

2.4

TMR11

Shikinejima S1

9910

34.20119°139.12376°

3

0.8

Tetraclitellachinensis

904 ± 40

Cal AD
1436–
1651

B

2.2

TMR12

Shikinejima S1

14931

34.20119°139.12376°

3

0.8

Tetraclitellachinensis1117 ± 47

Cal AD
1245–
1469

B

2.2

TMR13

Shikinejima S1

9911

34.20119°139.12376°

2.7

0.8

Tetraclitellachinensis

721 ± 34

Cal AD
1539–
1872

B

1.9

TMR14

Shikinejima S1

14932

34.20119°139.12376°

2.7

0.8

Tetraclitellachinensis

774 ± 43

Cal AD
1483–
1821

B

1.9

TMR15

Shikinejima S1

9912

34.20119°139.12376°

2.7

0.4

Cardita leana

1070 ± 41

Cal AD
1300–
1473

B

2.3

TMR16

Shikinejima S1

14933

34.20119°139.12376°

2.7

0.4

Cardita leana

1378 ± 38

Cal AD
1006–
1280

B

2.3

OUR22

Shikinejima S2

9917

34.19534°
139.12305°

3

0.4

Cardita leana

1399 ± 35

Cal AD
1002–
1252

B

2.6

OUR31

Shikinejima S3

9918

34.19486°
139.12267°

2.3

0.8

Tetraclitellachinensis1049 ± 36

Cal AD
1309–
1489

B

1.5

OUR32

Shikinejima S3

9919

34.19486°
139.12267°

2.3

0.8

Tetraclitellachinensis1152 ± 46

Cal AD
1216–
1452

B

1.5

NNU41

Shikinejima S4

9920

34.19420°
139.12238°

− 0.1

− 0.5

Cyphastrea
serailia

375 ± 40

Cal AD
1842–
1950

A

0.4

NNU42

Shikinejima S4

9921

34.19420°
139.12238°

− 0.1

− 0.5

Cyphastrea
serailia

215 ± 34

Cal AD
1875–
1950

A

0.4

NNU43

Shikinejima S4

9922

34.19420°
139.12238°

− 0.1

− 0.5

Cyphastrea
serailia

302 ± 37

Cal AD
1857–
1950

A

0.4

NNU51

Shikinejima S5

9923

34.19416°
139.12198°

1.4

0.8

Tetraclitellachinensis

275 ± 29

Cal AD
1862–
1950

A

0.6

Samplename

Locality

Site Laboratory
number(YAUT-)

TMR6

Shikinejima S1

TMR7

Kitamura et al. Progress in Earth and Planetary Science (2017) 4:30

Page 8 of 17

Table 2 Results of 14C dating in the present study (Continued)
Coordinates(lat/long)

Height(m)

Uppergrowth
limit (m)Materials

Conventional
14
C age (years
BP)

Calibratedage (2σ)Groups Total
minimum
uplift (m)14936

34.19416°
139.12198°

1.4

0.8

Tetraclitellachinensis

539 ± 41

Cal AD
1720–
1950

A

0.6

Shikinejima S6

9924

34.19196°
139.13216°

3.7

0.4

Cardita leana

1260 ± 38

Cal AD
1090–
1346

B

3.3

K111

Kozujima

K1

18504

34.14110°139.08083°

0.54

0.4

Tetraclita sp.

− 796 ± 41

modern

A

0.14

K112

Kozujima

K1

18505

34.14110°139.08083°

0.64

0.8

Serpulidae
sp.

439 ± 29

Cal AD
1766–
1950

A

− 0.16

K113

Kozujima

K1

18506

34.14110°139.08083°

0.99

0.4

Tetraclita sp.

472 ± 27

Cal AD
1727–
1950

A

0.59

K114

Kozujima

K1

18507

34.14110°139.08083°

1.36

0.4

Tetraclita sp.

486 ± 39

Cal AD
1724–
1950

A

0.96

K121

Kozujima

K1

18509

34.14110°139.08083°

2.42

0.8

Tetraclitellachinensis

1227 ± 34

Cal AD
1140–
1410

B

1.62

K122

Kozujima

K1

18511

34.14110°139.08083°

2.98

0.8

Tetraclitellachinensis

1280 ± 30

Cal AD
1066–
1331

B

2.18

K123

Kozujima

K1

18512

34.14110°139.08083°

3.28

0

Tubastraea
coccinea

1414 ± 28

Cal AD
975–1255

B

3.28

K131

Kozujima

K1

18513

34.14110°139.08083°

4.36

0.8

Rhizotrochus
typus

1626 ± 45

Cal AD
716–1031

C

3.56

K132

Kozujima

K1

18514

34.14110°139.08083°

4.91

0.8

Rhizotrochus
typus

1663 ± 57

Cal AD
682–1015

C

4.11

K133

Kozujima

K1

18517

34.14110°139.08083°

5.58

0.8

Rhizotrochus
typus

1594 ± 42

Cal AD
735–1053

C

4.78

K141

Kozujima

K1

18518

34.14110°139.08083°

6.2

0.8

Rhizotrochussp.

1725 ± 42

Cal AD
647–956

C

5.4

K142

Kozujima

K1

18519

34.14110°139.08083°

6.91

0.8

Rhizotrochus
typus

1663 ± 33

Cal AD
696–993

C

6.11

K143

Kozujima

K1

18521

34.14110°139.08083°

6.91

0

Tubastraea
coccinea

1568 ± 29

Cal AD
775–1073

C

6.91

K1441

Kozujima

K1

18523

34.14110°139.08083°

6.61

0.8

Rhizotrochus
typus

1503 ± 32

Cal AD
843–1173

C

5.81

K1442

Kozujima

K1

22004

34.14110°139.08083°

6.61

0

Chama
iostoma

1639 ± 33

Cal AD
715–1015

C

6.61

K145

Kozujima

K1

18524

34.14110°139.08083°

6.51

0.8

Rhizotrochus
typus

1537 ± 51

Cal AD
786–1154

C

5.71

K146

Kozujima

K1

18525

34.14110°139.08083°

6.51

0

Tubastraea
coccinea

1779 ± 67

Cal AD
550–940

C

6.51

K211

Kozujima

K2

18526

34.13131°139.07457°

9.43

0

Tetraclita sp.

1931 ± 33

Cal AD
426–700

D

9.43

K212

Kozujima

K2

22005

34.13131°139.07457°

9.43

0.4

Cardita leana

2085 ± 29

Cal AD
250–585

D

9.03

K213

Kozujima

K2

22006

34.13131°139.07457°

9.43

0.8

Lithophaga
curta

2035 ± 36

Cal AD
305–641

D

8.63

K214

Kozujima

K2

22007

34.13131°139.07457°

9.43

0

Tetraclita sp.

1982 ± 25

Cal AD
395–665

D

9.43

Samplename

Locality

Site Laboratory
number(YAUT-)

NNU51

Shikinejima S5

ISZ61

Kitamura et al. Progress in Earth and Planetary Science (2017) 4:30

Page 9 of 17

Table 2 Results of 14C dating in the present study (Continued)
Samplename

Locality

Site Laboratory
number(YAUT-)

Coordinates(lat/long)

Height(m)

Uppergrowth
limit (m)Materials

Conventional
14
C age (years
BP)

Calibratedage (2σ)Groups Total
minimum
uplift (m)K215

Kozujima

K2

22009

34.13131°139.07457°

9.43

− 0.4

Vermetus
tokyoensis

2107 ± 35

Cal AD
218–572

D

9.83

K22

Kozujima

K2

18527

34.13131°139.07457°

11.43

0.4

Cardita leana

2156 ± 47

Cal AD
142–528

D

11.03

K31

Kozujima

K3

18531

34.12475°
139.07517°

2.09

0.8

Serpulidae
sp.

1301 ± 35

Cal AD
1056–
1316

B

1.29

K321

Kozujima

K3

18532

34.12475°
139.07517°

2.45

0.4

Cardita leana

1789 ± 40

Cal AD
580–885

C

2.05

K322

Kozujima

K3

22011

34.12475°
139.07517°

2.45

− 0.4

Vermetus
tokyoensis

1617 ± 39

Cal AD
726–1034

C

2.85

K323

Kozujima

K3

22012

34.12475°
139.07517°

2.45

0.8

Lithophaga
curta

1553 ± 31

Cal AD
783–1100

C

1.65

K33

Kozujima

K3

22013

34.12475°
139.07517°

1.22

0.4

Tetraclita sp.

480 ± 32

Cal AD
1725–
1950

A

0.82

K411

Kozujima

K4

18534

34.12462°
139.07516°

0.02

0.8

Serpulidaesp.

− 816 ± 34

ModernA− 0.78

K4121

Kozujima

K4

18536

34.12462°
139.07516°

0.32

0.8

Serpulidae
sp.

− 923 ± 46

ModernA− 0.48

K4122

Kozujima

K4

22014

34.12462°
139.07516°

0.32

0.4

Tetraclita sp.

− 1121 ± 23

Modern

A

0.32

K413

Kozujima

K4

18636

34.12462°
139.07516°

0.62

0.8

Dendropoma
planorbis

530 ± 31

Cal AD
1723–
1950

A

− 0.18

K421

Kozujima

K4

18637

34.12462°
139.07516°

2.02

0.8

Tetraclitellachinensis

1037 ± 28

Cal AD
B
1306–1511

1.22

K422

Kozujima

K4

18638

34.12462°
139.07516°

3.92

0.8

Serpulidae
sp.

1755 ± 28

Cal AD
626–901

3.12

GaK9718*

Shikinejima 1
GaK-9718(S1)

34.20119°139.12376°

3.2–3.6 0.8

Tetraclitellachinensi

1980 ± 130

2.4–2.8

GaK9717*

Shikinejima 1
GaK-9717(S1)

34.20119°139.12376°

3.0–3.1 0.8

Megabalanus
rosa

1830 ± 130

2.2–2.3

GaK9720*

Shikinejima 1
GaK-9720(S1)

34.20119°139.12376°

2.6

0.8

Tetraclitellachinensi

1350 ± 100

1.8

GaK9721*

Shikinejima 1
GaK-9721(S1)

34.20119°139.12376°

2.6

0.8

Saccostrea
kegaki

2540 ± 290

1.8

GaK9719*

Shikinejima 2

GaK-9719

34.19165°
139.13214°

4.2

0.8

Tetraclita
japonica

1010 ± 300

3.4

GaK9722*

Shikinejima 3

GaK-9722

34.19184°
139.13223°

3.9–5.1 0.8

Tetraclitellachinensi

1530 ± 100

3.1–4.3

C*Ota et al. (1983)

Their 14C ages exactly matched each other and ranged fromAD 1820 to present (Table 2). Observations made while
scuba diving indicate that living hermatypic corals at thissite occupy water depths greater than 0.5 m.
Site S5 is a marine cave located in a cliff on the east sideof Nakanoura Bay. The cave is 1.8 m wide, 3.0 m high,and 6.0 m long. We collected two well-preserved individual specimens of T. chinensis from inside the cave at anelevation of 1.8 m amsl. Their 14C ages fall within AD
1720 to present (Table 2).

Site S6 is located on bedrock on the Ishijirogawa coast,
at about + 3.7 m amsl. One specimen of C. leana was collected and yielded a 14C age of AD 1077–1385 (Table 2).
Kouzushima

Site K1 is located on the southern side of Nagumi Bay andis divided into four subsites (K11, K12, K13, and K14)
(Figs. 2 and 9). Well-preserved individuals of Tetraclita sp.,
Serpulidae sp., and T. chinensis were observed at 0.5–3.0 m
amsl on coastal bedrock at sites K11 and K12 (Table 2). We

Kitamura et al. Progress in Earth and Planetary Science (2017) 4:30

ab

6 September 2015 (11:20 am on Japan Time)b

6 September 2015 (11:20 am on Japan Time)

Fig. 6 Photographs of a site J1 on Jinaijima and b encrusting
masses of P. kraussii

aPage 10 of 17

collected many well-preserved in situ azooxanthellate corals
of Tubastraea coccinea and Rhizotrochus typus at 3.3–
6.9 m amsl from sites K13 and K14 (Fig. 9; Table 2) but did
not find intertidal organisms such as T. chinensis and S.
kegaki. Although many studies of emerged Holocene marine fossils have been performed in Japan (e.g., Ishibashi etal. 1979; Ota et al. 1983; Kayanne et al. 1987; Maemoku
1988; Miyauchi 1990; Iryu et al. 2009; Kitamura et al. 2014,2015, 2016, in press), no previous reports of the occurrenceof R. typus are known to the authors. All of the coral specimens collected during the present study are 100% aragonite
and therefore are not susceptible to subaerial diagenesis,
because recrystallization of coral aragonite to calcite occurs
in a subaerial setting (Sayani et al. 2011). The 14C ages of
specimens at this site range from AD 613 to present andbecome older with increasing elevation (Table 2).
Site K2 is located at 9.4–11.4 m amsl on bedrock on thenorthwest side of Sawajiri Bay (Figs. 2 and 10). At this location, samples were taken at the highest elevation of anysite. We collected well-preserved Tetraclita sp., C. leana,
Lithophaga curta, and Vermetus tokyoensis. Their 14C ages
fall within the range AD 161–686 (Table 2).
Site K3 is located on bedrock north of Kouzushima Harbor, at 1.2–2.5 m amsl (Fig. 2). Well-preserved Serpulidae
sp., C. leana, V. tokyoensis, and L. curta were collected with
14
C ages ranging from AD 600 to the present (Table 2).
Site K4 is located on bedrock south of Maehama (Fig. 2).
This site yielded individuals of Serpulidae sp., Tetraclitasp., Dendropoma planorbis, and T. chinensis at 0–3.9 m
amsl. The 14C ages of the specimens range between AD
626 and the present day and become older with increasing
elevation (Table 2).
b

1 cm
S1

3 May 2014 (5:10 pm on Japan Time)

c

1 cm

Fig. 7 Photographs of a site S1 on Shikinejima, b close-up view of a specimen of T. chinensis (sample TMR1), and c the in situ bivalve C. leana(sample TMR18)

Kitamura et al. Progress in Earth and Planetary Science (2017) 4:30

aPage 11 of 17bb

4 May 2014 (11:40 am on Japan Time)

4 May 2014 (11:40 am on Japan Time)

Fig. 8 Photographs of a site S4 on Shikinejima and b in situ colonies of hermatypic C. serailia (sample NNU41)

Emerged sessile assemblages

Figure 11 shows the elevations and ages (2σ) of emerged
sessile assemblages from this study and from Ota et al.
(1983). Rather than a simple linear trend, the data show
stepwise changes in elevations at particular times, meaning that uplift occurred in a series of discrete events rather than as a gradual and continuous process. The
mechanism of such uplift is a seismic event or relatively
short-lived uplift associated with volcanic activity, suchas the AD 2000 eruption of Miyakejima volcano (Fig. 4).
Based on these elevations and ages, the Shikinejima specimens cluster into two groups (A and B; Fig. 11 andTable 2). Group A occurs between − 0.1 and 1.4 m amsl at
Shikinejima (sites S4 and S5), Niijima (site N1), Jinaijima(site J1), and Kouzushima (sites K1, K3, and K4). The agesof the Group A specimens range from AD 1723 to present.
Group B samples are defined as those taken at elevations
above Group A and are located between 2.0 and 4.0 m amsl
at Shikinejima (sites S1, S2, S3, and S6) and Kouzushima(sites K1, K3, and K4); they yield ages of AD 975–1872.
Groups C and D are only found on Kouzushima (sites K1–
4). Samples in Group C have elevations between those ofGroups B and D. Although the elevations of four specimens(K321, K322, K323, and K422) fall within the range definedfor Group B, their ages are consistent with other Group C
samples, and thus, they are considered to belong to Group
C. Groups C and D occur at elevations of 2.45–6.91 m amsl
and 9.43–11.43 m amsl, respectively (Fig. 11), with no overlap in elevation. The corresponding age ranges for Groups
C and D are AD 600–1165 and AD 161–686, respectively.

Discussion
All of the collected specimens are more recent than AD
160 (Fig. 11). Since relative sea-level reconstructions
show that sea level was likely stable at the study site during the past 2000 years (Sato 2008; Woodroffe et al.
2012; Yokoyama et al. 2012; Tanigawa et al. 2013;
Tanabe et al. 2016), the occurrence of the emerged sessile assemblages cannot be explained by eustatic sea levelchanges; instead, it requires local crustal uplift.

The magnitude of the uplift is best estimated by direct
measurement of the elevational difference between theupper limit of the uplifted remains and the corresponding
upper limit of its present homolog (Laborel and LaborelDeguen 1994; Pirazzoli et al. 1999). Although the estimatedvalues represent the minimum amount of uplift, this procedure eliminates uncertainties derived from estimates ofthe bathymetric ranges of each species. If this procedure
was not applied, we would have to make a subjective decision about whether any individuals of a species lived higher
than the collected specimens but were not preserved. We
therefore make this assumption since there is no reliable
way of resolving this ambiguity. This estimation method
was also used by Pirazzoli et al. (1999), Kitamura et al.
(2014, 2015, 2016), and Hamada et al. (2016).
Using the above procedure, we calculated the upliftamount of each specimen. As noted below, the maximum
value of each group was derived for each island from specimens found at the highest position in the group. The estimated maximum uplift was regarded as rapid uplift, basedon the following conceptual assumptions: (1) each groupof emerged assemblages was created by a single uplift
event or by gradual uplift over a finite period of time and(2) no vertical crustal motion occurred in the study area
during the intervals between discrete uplift events. Theseassumptions mean that our definition of an uplift event
includes both coseismic uplift and relatively short-lived
uplift due to volcanic activity. The estimated minimum
total amount of uplift for each specimen is shown in
Table 2. The defining events of each of Groups A–D arereferred to (in reverse chronological order) as uplift events
1, 2, 3, and 4, respectively.
Uplift event 1

Group A consists of C. gigas and S. kegaki at Niijima Island, P. kraussii at Jinaijima, T. chinensis and C. serailia
at Shikinejima, and D. planorbis, Serpulidae sp., and Tetraclita sp. at Kouzushima (Table 2).
C. gigas lives in intertidal and subtidal zones, while
S. kegaki inhabits the intertidal zone at elevations

Kitamura et al. Progress in Earth and Planetary Science (2017) 4:30

aPage 12 of 17

10

100 m

Site K14 (Fig. 9e)
8Site K13 (Fig. 9b)

A

6
B

4

Site K12Site K11

Barnacle
Serpulidae sp.
Coral

2

Chama iostoma

0
(m)

A

B
73.6 mbdc
25 March 2014
(3:00 pm on Japan Time)

2 cm

e

g

f

2

1
Fig. 9 a Sketch profiles at site K1. b Photograph of a small emerged gorge-shaped inlet at site K1 on Kouzushima. c Close-up of the exposure.
d Occurrence of R. typus (sample K131). e Close-up of the exposure. f Occurrence of R. typus (sample K142) (1) and Tubastraea coccinea (sampleK143) (2). g Occurrence of R. typus (sample K141)

from − 0.8 to + 0.8 m amsl (Okutani 2000). As noted
above, since the upper limit of living S. kegaki is located at +0.4 m amsl, we used both +0.8 m (Okutani
2000) and + 0.4 m (this study) amsl as the upper limit(Table 2). Because the upper limit of C. gigas, which
is absent in the study site, is the same as that of S.
kegaki, the values + 0.8 and + 0.4 m amsl were used
for C. gigas.

The upper limit of encrustation by abundant calcareous tubes of living P. kraussii is located at an elevationof 0.1 ± 0.1 m amsl on Boso Peninsula in Central Japan(Kayanne et al. 1987) and at 0.1–0.2 m amsl on Izu Peninsula in the same region (Kitamura et al. 2014). The
value of 0.2 m amsl is used as the upper limit of encrustation of P. kraussii because we did not find living individuals in the study area. Local disappearances of C.

Kitamura et al. Progress in Earth and Planetary Science (2017) 4:30

aPage 13 of 17

4 September 2014 (10:20 am on Japan Time)

c

b

2 cm

1 cm
d

e

1 cm
Fig. 10 Photographs of a site K2 on Kouzushima, b the emerged sessile assemblages, c specimen of C. leana (sample K22), d the emerged sessile
assemblages, and e specimen of Tetraclita sp. (sample K211)

gigas and P. kraussii indicate that uplift of the area has
made it an unsuitable environment for these species.
Identical phenomena were documented in the southern
Izu Peninsula by Kitamura et al. (2014).
T. chinensis and D. planorbis inhabit the intertidal
zone from − 0.8 to + 0. 8 m amsl (Okutani 2000;
Yamaguchi and Hisatsune 2006). This is consistent with
our observation that the upper limit of T. chinensis islocated at about + 0.8 m amsl. Tetraclita sp. lives aroundthe middle tidal zone (Yamaguchi and Hisatsune 2006).
At site S4, where the specimens of C. serailia were
found, our observations while scuba diving indicate thatliving colonies of C. serailia only inhabit water depths
greater than 0.5 m below mean sea level.
Based on the vertical distribution of these living species,
uplift event 1 is estimated to have a minimum uplift of
0.5 m at Niijima (samples N11–N14), 0.4 m at Jinaijima(J1), 0.6 m at Shikinejima (sample NNU51), and 1.0 m(0.96 m) at Kouzushima (sample K114). Since the 14C
content of many Group A specimens has been influenced
by the atomic bomb effect, the uplift of Group A musthave occurred after 1950. As noted above, Niijima andKouzushima experienced up to 0.2 and 0.9 m of gradualuplift during the periods 2000–2014 and 1990–2014,

Kitamura et al. Progress in Earth and Planetary Science (2017) 4:30

Page 14 of 17

Fig. 11 Elevations and ages of emerged sessile assemblages at the study sites

respectively (Fig. 4). These uplift events were caused by
the development of a pressure source beneath Kouzushima and dike intrusion associated with the AD 2000
eruption of Miyakejima Volcano, respectively (Kimata etal. 2000; Murakami et al. 2001; Nishimura et al. 2001;
Yamaoka et al. 2005). Thus, we conclude that this episodeof crustal deformation, from 1990 to 2014, contributed tothe emergence of Group A. The differences between our
uplift estimates and values derived from instrumental data
are 0.3 m at Niijima, 0.2 m at Jinaijima, and 0.4 m at
Shikinejima, all of which can be explained by uplift during the period before GPS observation. Uplift was recorded by GPS at these sites as well as at Kouzushima.
Thus, Niijima, Jinaijima, and Shikinejima may have experienced gradual uplift before GPS observation. Dataof the present data were used to determine the minimum uplift that occurred at Niijima (0.5 m), Jinaijima(0.4 m), Shikinejima (0.6 m), and Kouzushima (0.9 m)
during uplift event 1. Many specimens of C. gigas andS. kegaki at Niijima that were found within their living
depth ranges were probably killed by burial under sanddue to local changes in coastal topography.
Uplift event 2

Group B includes C. leana and T. chinensis at Shikinejima and T. chinensis, T. coccinea, and Serpulidae sp. at
Kouzushima (Table 2). Cardita leana inhabits the middle to lower intertidal zone from − 0.8 to + 0.4 m amsl
(Okutani 2000), and T. coccinea commonly inhabitswater depths of 0–60 m off southwest Japan (Sentoku

Kitamura et al. Progress in Earth and Planetary Science (2017) 4:30

and Ezaki 2012). Based on the vertical distribution of living species, the minimum total uplift of Group B since
the time of active growth of the assemblages is estimatedto be 3.3 m at both Shikinejima (sample ISZ61) andKouzushima (sample K123). If the actual uplift during
event 1 was equal to the minimum uplift that we
estimate for event 1 in this study, then a minimum of
2.7 m of uplift occurred at Shikinejima and 2.4 m atKouzushima during uplift event 2.
With the exception of one specimen that yields an ageof AD 1539–1872 (sample TMR13), the 14C age rangesof Group B specimens coincide with, or exceed, the AD
1498 Meio earthquake. The age range of sample TMR13(AD 1539–1872) indicates that the uplift of Group B
was caused by an event that occurred after the Meio
earthquake. However, we do not exclude the possibility
that uplift event 2 was caused by the AD 1498 Meio
earthquake, because the ~ 30-year difference between
the age of the youngest specimen and the earthquake
could be explained by temporal changes in the valueof the local correction to the 14C age (ΔR). Hirabayashi
et al. (2017) recently reported that ΔR data from
Okinawa for 1900–1950 fluctuated from − 136 ± 42 to
62 ± 50 years. Since both the study area and Okinawa
are in the Kuroshio region, temporal changes in ΔR
will affect the calibration of 14C ages used to provide
calendar dates for our specimens. Thus, we cannot exclude the possibility that uplift event 2 at Shikinejima
and Kouzushima was caused by the Meio earthquake,in contrast to the interpretation of Ota et al. (1983).
Other possible mechanisms include another strong
earthquake (i.e., MW ≥ 6.0) or dike intrusion. Manystrong earthquakes have struck the study area (Hagiwara
and Omote 1936; Honda 1938; Miura 1939; Hamada
2001; Fig. 3). As noted above, dike intrusion associatedwith the AD 2000 eruption of Miyakejima contributed to
uplift event 1 at Kouzushima, Shikinejima, and Niijima(Nishimura et al. 2001; Yamaoka et al. 2005). According toTsukui and Suzuki (1998), Miyakejima erupted in AD
1469, which might have caused uplift event 2.
Uplift event 3

Group C is found only on Kouzushima and has a wider
range of observed elevations than the other groups. This
group consists of R. typus (site K1), T. coccinea (site K1),
Chama iostoma (site K1), C. leana (site K3), V. tokyoensis(site K3), L. curta (site K3), and Serpulidae sp. (site K4)(Table 2). The bathymetric range of V. tokyoensis is lower
intertidal (− 0.4 m amsl) to subtidal; C. iostoma is foundfrom the lower intertidal zone to water depths of 20 m, andL. curta inhabits the intertidal zone to depths of 20 m
(Okutani 2000). We observed Serpulidae sp. within theintertidal zone at Kouzushima. Ogawa et al. (1996) describe
Rhizotrochus niinoi, a junior synonym of R. typus (Cairns,

Page 15 of 17

1994), as living from the intertidal zone to a maximum
depth of 18 m in Kanaya, Chiba, Central Japan. Based on
the vertical distribution of living species, the minimum total
uplift of Group C since active growth ceased is estimated tobe 6.9 m at site K1 (K142), 2.9 m at site K3 (K322), and
3.1 m at K4 (K422). If the uplifts in events 1 (0.9 m) and 2(2.4 m at K1) were no more than the minimum estimates,
then the total uplift is 3.3 m. Thus, we estimate that a minimum of 3.6 m uplift occurred at site K1. While the minimum total uplift of Group C at sites K3 (2.9 m) and K4(3.1 m) is smaller than the total of 3.3 m when assumption(2) holds, the amount of uplift during events 2 and 3 at sites
K3 and K4 is smaller than that at site K1. A similar spatial
gradient in uplift was reported by Kimata et al. (2000), whostated that the uplift rate in the northern part of their study
area was nearly twice as high as that in the southern part
during 1997–2000.
All 14C ages of Group C specimens fall within the period
AD 550–1170 BC. During this interval, the AD 838
eruption of Tenjosan volcano on Kouzushima represents
the most probable cause of uplift event 3. With the exception of one specimen that yields an age of AD 843–1173(sample K1441), the 14C age ranges of Group C specimens
overlap the eruption date. The ~ 30-year difference between
the age of the youngest specimen and the eruption could
be explained by temporal changes in ΔR (Hirabayashi et al.
2017). Uplift event 3 could be explained by lava dome formation during the eruption of Tenjosan volcano (Isshiki1982); other possible mechanisms include strong earthquakes (i.e., MW ≥ 6.0) and dike intrusion. The AD 838–
886 eruption of Miyakejima (Tsukui and Suzuki 1998) may
have caused uplift event 3.
Uplift event 4

Group D, which is found only at site K2 in Kouzushima, includes Tetraclita sp., V. tokyoensis, C. leana, and L. curta(Table 2). Based on the vertical distribution of living species,
the minimum total uplift of Group D since the time of active growth is estimated to be 11.0 m (sample K22). Since
the other groups are not seen at site K2, the total amountof uplift over events 1–3, which ranges from 2.9 m (site K3)
to 7.7 m (at site K1), indicates 3.3–8.1 m of uplift during
event 4.
The 14C ages of Group D specimens lie in the range
AD 161–686, indicating that the timing of event 4 overlaps volcanic activity that occurred about 230 years before the AD 838 eruption of Kouzushima (Togashi1984). Thus, we propose that uplift event 4 was related
to this volcanic activity, as well as strong earthquakes(i.e., MW ≥ 6.0) and dike intrusion.
At Shikinejima, the non-calibrated 14C ages of T. chinensis, Tetraclita japonica, Megabalanus rosa, and Saccostrea
kegaki (Table 1) presented by Ota et al. (1983) are older
than those obtained in this study (Fig. 11). Four specimens

Kitamura et al. Progress in Earth and Planetary Science (2017) 4:30

(GaK-9717, GaK-9718, GaK-9720, and GaK-9721) haveelevations similar to those of Group B, so it is likely that
their 14C ages were influenced by contamination by deadcarbon after being uplifted with Group B. Spurgeon et al.
(2003) obtained radiocarbon dates of shells and cements ofcarbonate-cemented shell debris located along the coast of
the Florida Peninsula, USA. Their results show that thecement ages were 1400–1600 years older than those of theshells. Spurgeon et al. (2003) proposed that dead carbon
was introduced during the dissolution–cementation
process, causing the cement to yield dates much older thanwhen cementation likely occurred. On the other hand, theelevations of two specimens (GaK-9719 and GaK-9722) are~ 1.1 m higher than in Group B. This may indicate that
uplift took place before uplift event 2. However, no further
comparison between the results of Ota et al. (1983) and thisstudy is possible, because we cannot measure the 14C agesof the specimens examined by Ota et al. (1983).

Conclusions
We re-examined Holocene crustal movements at
Niijima, Jinaijima, Shikinejima, and Kouzushima basedon marine species compositions and determined the
AMS 14C ages of emerged sessile assemblages. Our conclusions are as follows:
1. We identified four groups of emerged sessile
assemblages that we infer to have been uplifted
during four rapid events (uplift events 1–4). The
ages of these events are estimated to be after AD
1950, AD 786–1891, AD 600–1165, and AD 161–
686, respectively. The minimum amounts of upliftduring events 1–4 are estimated to be 0.4–0.9, 2.4–
2.6, 3.6, and 3.3–8.1 m, respectively.
2. Uplift event 1 was caused by the appearance of apressure source and dike intrusion associated with
the AD 2000 eruption of Miyakejima Volcano. Thesemechanisms, along with strong earthquakes, are themost likely causes of uplift events 2, 3, and 4.
Considering the timing of uplift event 2, there is
the possibility that the AD 1498 Meio earthquake
caused the event. The volcanic eruption of AD 838
and a previous eruptive episode in Kouzushima arealso candidate mechanisms for uplift events 3 and 4,
respectively.
Abbreviations
AMS: Accelerator mass spectrometry; amsl: Above mean sea level
Acknowledgements
We thank Drs. Toshiyuki Yamaguchi, Kaoru Sugihara, and Asuka Sentoku forassistance with identifying barnacles and corals, respectively. We thank threeanonymous reviewers and associate editor Ken Ikehara for their thoughtful
input into this manuscript. The sampling of specimens was conducted witha permit issued by the Agency for Cultural Affairs, Kanto Regional Ministry of
the Environment.

Page 16 of 17

Authors’ contributions
AK conceived and designed the study and collected samples. TI identified
specimens of mollusks and undertook 14C analysis of the samples. TI and YM
discussed the sources of crustal deformation. MI investigated the distributionof living corals. YM and YY undertook 14C analysis of the samples. YTidentified specimens of corals. All authors read and approved the final
manuscript.
Funding
This study was funded by Grants-in-Aid (26287126, 17H02972) awarded by
the Japan Society for the Promotion of Science.
Competing interests
The authors declare that they have no competing interests.

Publisher’s NoteSpringer Nature remains neutral with regard to jurisdictional claims inpublished maps and institutional affiliations.
Author details
1
Institute of Geosciences, Shizuoka University, 836 Oya, Suruga-ku, Shizuoka
422-8529, Japan. 2Center for Integrated Research and Education of Natural
Hazards, Shizuoka University, 836 Oya, Suruga-ku, Shizuoka 422-8529, Japan.
3
Atmosphere and Ocean Research Institute, University of Tokyo, Chiba
277-8564, Japan. 4Tottori University of Environmental Studies, 1-1
Wakabadai-kita, Tottori 689-1111, Japan.
Received: 28 December 2016 Accepted: 3 October 2017

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