SIT03-P01

会場:コンベンションホール

時間:5 月 26 日 18:15-19:30

合成カンラン岩の漸次的温度変化時の電気伝導度連続測定：部分融解の影響
Continuous measurements of electrical conductivity of synthetic peridotite under changing temperature: Melting effect
末善 健太 1∗ ; 平賀 岳彦 1
SUEYOSHI, Kenta1∗ ; HIRAGA, Takehiko1
11

東京大学地震研究所
Earthquake Research Institute, The University of Tokyo

Transport properties of the mantle (ex. electrical conductivity, viscosity, and seismic attenuation) sharply changes during ascend of the mantle especially at around mantle solidus. Electrical conductivity is considered to be the most sensitive property
to the presence of partial melt. To understand how partial melting changes the conductivity of ascending mantle (ex. mid-oceanridge), we measured the electrical conductivity of synthesized peridotite samples, which have different manners of melting withtemperature, during slow increases and decreases in temperature under atmospheric pressure.
Three types of samples, forsterite (80%) + diopside (20%), forsterite (95%) + diopside (5%) and forsterite (50%) + enstatite(40%) + diopside (10%) with addition of 0.5% spinel, were synthesized from Mg(OH)2 , SiO2 , CaCO3 and MgAl2 O4 powders
with particle size of <50 nm. We continuously measured the electrical conductivity of these samples at temperature range from1100 ℃ to 1400 ℃. Microstructures of the samples quenched from above solidus were observed by scanning electron microscopy(SEM) in order to measure the melt fraction.
The electrical conductivity at well below (>50 ℃) solidus of the forsterite + diopside samples exhibited a linear distribution
in their Arrhenius plots indicating that a single mechanism controls. Such linear relationship was no longer observed at highertemperature regime exhibiting its exponential increase until the temperature reached to produce a phase assembly of forsterite +melt. In addition, the grain size dependence on electrical conductivity disappeared at temperature between 1350 ℃ and 1360 ℃,
indicating that the effective conductive path changed from grain boundary to other path. The result indicates that there is a phaseassembly of forsterite + diopside + melt phase at around 1360 ℃ which has not been appeared in the previously reported phase
diagram (Kushiro and Schairer, 1963).
Monotonic increase of electrical conductivity was observed above solidus of the forsterite + enstatite + diopside + spinel sample, and such increment is considered to be strongly related melt fraction changing with temperature, which is supported fromSEM observation.

キーワード: 電気伝導度, カンラン岩, 部分融解, メルト分率
Keywords: electrical conductivity, peridotite, partial melting, melt fraction

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SIT03-P02

会場:コンベンションホール

時間:5 月 26 日 18:15-19:30

高温高圧下における金の単結晶弾性の測定
Measurement of single crystal elasticity of Gold (Au) under high temperature and highpressure
米田 明 1∗ ; 福井 宏之 2 ; 平尾 直久 3 ; 鎌田 誠司 4 ; バロン アルフレッド 5
YONEDA, Akira1∗ ; FUKUI, Hiroshi2 ; HIRAO, Naohisa3 ; KAMADA, Seiji4 ; BARON, Alfred511

岡山大地球研, 2 兵庫県立大, 3 高輝度光科学研究センター, 4 東北大学大学院理学研究科, 5 理化学研究所
ISEI, Okayama Univ., 2 Univ. of Hyougo, 3 JASRI, 4 Graduate school of Science, Tohoku University, 5 RIKEN

Single crystal elasticity of gold (Au) has been measure by inelastic X ray scattering method under high pressure. A few tens
micrometer Au single crystal was prepared from a large commercial crystal by using FIB technique. The small crystal was placed
inside a gasket hole of DAC apparatus. We succeeded to measure single crystal elasticity at 0.8 GPa and 3.2 GPa; the pressures
were determined by the Ruby scale. ˜100 peaks were observed at each pressure, and used to constrain the three independent
constants of C11 , C12 , and C44 . The resulted elastic constants are consistent with the previous data at ambient pressure.
We observed that C11 and C44 increase with increasing pressure, and C12 decreases with increasing pressure. We will expand
the pressure range and temperature range of the measurement to establish the equation of state of gold with unprecedented
accuracy.

キーワード: 金, 単結晶, 弾性, 高圧
Keywords: Gold, single crystal, elasticity, high pressure

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SIT03-P03

会場:コンベンションホール

時間:5 月 26 日 18:15-19:30

半導体ダイヤモンドヒーターによる高圧力下での高温発生
High temperature generation using semiconductor diamond heater at high pressure
伊藤 英司 1∗ ; 米田 明 1 ; Xie Longjian1 ; 辻野 典秀 1
ITO, Eiji1∗ ; YONEDA, Akira1 ; XIE, Longjian1 ; TSUJINO, Noriyoshi1
11岡山大学地球物質研究センター
Institute for Study of the Earth’s Interior, Okayama University

Melting relations of the Earth materials are information essentially important to clarify the early differentiation and evolutionof the Earth. Nevertheless melting experiments using the Kawai-type apparatus under mid mantle conditions are impossible
because of limited temperature generation. Following Shatsky et al. (2009), we have tried to generate temperatures higher than
3500 K adopting B-doped semiconductor diamond heater. In order to carry out melting experiments at higher than 50 GPa, weadopt sintered diamond anvils. Temperature (T) is estimated by extrapolating a T-W (power) curve constructed up to 2600 C
based on the W/re thermocouple measurement. Our T-generation reached ca. 4700 C at 55GPa.
キーワード: 高温発生, 半導体ダイヤモンドヒーター, 川井式 装置, 焼結ダイヤモンド
Keywords: High temperature generation, Semiconductor diamond heater, Kawai-type apparatus, sintered diamond

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SIT03-P04

会場:コンベンションホール

時間:5 月 26 日 18:15-19:30

Numerical Simulation on Subduction of the Pacific Plate into Northeast China and the
Seismogenic Mechanism of Earthquake
Numerical Simulation on Subduction of the Pacific Plate into Northeast China and theSeismogenic Mechanism of Earthquake
JIAO, Mingruo1∗ ; BO, Zhang1
JIAO, Mingruo1∗ ; BO, Zhang1
11

Earthquake Adimistration of Liaoning Province, Shenyang, 110034, P.R.China
Earthquake Adimistration of Liaoning Province, Shenyang, 110034, P.R.China

The Pacific Plate is subducted into Northeast China up to 660km deep, leading to a series of deep earthquakes in Hunchun
zones of Jilin province, which was noticed by seismologists in the past. As the only deep-earthquake belt in China, its occurrencetime, locations and magnitudes are closely associated with Japan trench earthquakes and shallow earthquakes in Northeast China.
Until now, seismologists attached great importance to this phenomenon and researched it in various aspects. On the one hand,research results confirmed the above phenomenon. On the other hand, masses of important results were obtained including thestructure of the Pacific subducting plate, lithosphere structure in Northeast China, the earthquake focal mechanism and the seismic dynamic mechanism about the deep and shallow earthquakes. But until now, there is seldom systematic research about therelationship among the Pacific plate, deep and shallow earthquakes using numerical simulation method. Therefore, this paper
will study their relationships and furtherly explore the tectonic stress field and dynamics environment in Northeast China.
Based on the geology data and the seismic velocity structure in Northeast China, we built the 2D vertical model along the 45
degree latitude ranging from 104 to 144 degree longitude with 0-660km deep to simulate the Pacific plate subducting to Northeast
China using finite element numerical simulation method. According to motion rate of the Pacific plate to the Eurasian plate, theboundary conditions are given. The model with the typical tectonic belts, such as Tanlu fault, can explain the earthquake mechanism and study the stress fields and displacement fields. Besides the relationship between fault belts and shallow earthquakes isdiscussed.Through numerical simulation and comprehensive analysis, some conclusions are obtained as follows:(1) The Pacific plate subduction into Northeastern China is the main dynamic resource causing a series of deep-focal andshallow-focal earthquakes. The stress field shows that there are two main areas of stress concentration under the subduction of
the Pacific plate. It can help us to explain the relationship about the seismogenic mechanism between deep and shallow earthquakes.
(2) The displacement field and deformation field are given. The results show the displacement field and deformation field
are controlled by the Pacific plate subduction rates. Exist of low veloticy medium in the middle crust layer is in favor of theoccurrence of the shallow earthquakes.

キーワード: numerical simulation, subduction of the Pacific plate, deep and shallow earthquakes, Northeast China
Keywords: numerical simulation, subduction of the Pacific plate, deep and shallow earthquakes, Northeast China

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SIT03-P05

会場:コンベンションホール

時間:5 月 26 日 18:15-19:30

S-velocity structure of the crust and uppermost mantle of East Asia from ambient seismicnoise
S-velocity structure of the crust and uppermost mantle of East Asia from ambient seismic
noise
WITEK, Michael1∗ ; NING, Shuoxian1 ; KANG, Tae-seob2 ; VAN DER LEE, Suzan1 ; CHANG, Sung-joon3 ;NING, Jieyuan4
WITEK, Michael1∗ ; NING, Shuoxian1 ; KANG, Tae-seob2 ; VAN DER LEE, Suzan1 ; CHANG, Sung-joon3 ;NING, Jieyuan41
1Northwestern University, 2 Pukyong National University, 3 Kangwon National University, 4 Peking University
Northwestern University, 2 Pukyong National University, 3 Kangwon National University, 4 Peking University

We have collected continuous vertical-component broadband data from 1109 seismic stations in regional networks across
China, Korea, and Japan for the year 2011, and we have measured over half a million Rayleigh wave group velocity dispersion
curves from one-year stacks of station-pair ambient seismic noise cross-correlations. The Rayleigh wave group velocity dispersion curves are regionalized on a tessellated spherical shell grid in the period range 10 to 50 s to produce maps of Rayleighwave group velocity distributions. Maps at 10 seconds period match well with geologic features at the surface. In particular, weobserve low group velocities in the Songliao, Bohai Bay, Sichuan, Ordos, Tarim, and Junggar Basins in China, and the Ulleung
and Yamato Basins in the East Sea (Sea of Japan). Higher group velocities are observed in regions with less sediment cover.
At periods around 30 s, we observe group velocity decreases going from east to west in China, representing an overall trend ofcrustal thickening due to the collision between the Indian and Eurasian plates. The Ordos and Sichuan blocks show higher groupvelocities relative to the eastern margin of the Tibetan Plateau, possibly reflecting low temperatures in these cratons. Using theRayleigh wave group velocity distributions, we have performed 1D linear inversions at each node on the spherical shell grid toretrieve S-velocity perturbations with respect to the reference model LITHO1.0 of Pasyanos et al. (2014). This has allowed usto construct a 3D model of the crust and uppermost mantle for East Asia. We observe large-scale lateral variation in the crust
compared to the LITHO1.0 model. From 50 to 100 km depth, we observe a low-velocity mantle wedge underneath Japan andthe Strait of Korea, and at 100 km depth we see a general trend of increasing S-velocities from east to west, possibly reflecting
temperature/water content variations in the mantle.
キーワード: East Asia, tomography, ambient noise
Keywords: East Asia, tomography, ambient noise

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SIT03-P06

会場:コンベンションホール

時間:5 月 26 日 18:15-19:30

表面波位相速度から推定される沖縄トラフにおける 1 次元 S 波速度構造One-dimensional shear velocity structure beneath Okinawa trough inferred from surface
wave phase velocity
小林 励司 1∗ ; 福田 圭祐 2 ; 田崎 菜央子 3 ; 衛藤 綾乃 4
KOBAYASHI, Reiji1∗ ; FUKUDA, Keisuke2 ; TASAKI, Naoko3 ; ETOH, Ayano4
1

鹿児島大学大学院理工学研究科, 2 鹿児島大学理学部, 3 鹿児島大学理学部 現：海上自衛隊, 4 鹿児島大学理学部 現：加崎医院
1
Kagoshima University, 2 Kagoshima University, 3 Kagoshima University .Now at JMSDF, 4 Kagoshima University. Now at
Kasaki Clinic
沈み込み帯の構造は、観測点のある島弧直下の構造は盛んに研究が進められているが、背弧側の構造はその地域に地震計がほとんどないために、あまり進んでいないのが現状である。しかし、沈み込み帯全体のダイナミクスを明らかにする上で、島弧直下の構造だけではなく、背弧側の構造も知ることは重要である。
本研究では沖縄トラフに焦点を当てている。琉球弧はフィリピン海プレートが沈み込んでできている島弧である。その背弧には沖縄トラフがあり、ここは背弧拡大域と考えられている。沖縄トラフにおける地殻構造に関しては、海上保安庁が地震探査を行っており（例えば、堀内他, 2011）、モホ面の深さが求められている。上部マントルの構造に関しては
Nakamura et al. (2003) が沖縄トラフを含む琉球弧でのトモグラフィーを行い、P 波、S 波速度構造を求めている。他に中国の大陸構造の研究でその範囲の端として構造が求められているものもある（例えば、Huang and Zhao, 2006）が、背弧拡大の構造が分かるほどには解像度は高くない。したがって、まだダイナミクスの全体像はまだ良く分かっていない。
そこでを背弧域を含む南西諸島周辺の構造を解明することを最終的な目標とし、本研究ではまず沖縄トラフの平均的な 1 次元 S 波速度構造を求めることを目的とする。比較のために、拡大する前の構造と考えられる東シナ海大陸棚の 1次元 S 波速度構造も求める。
まず、2 点法によりレイリー波、ラブ波の位相速度を測定し、分散曲線を得た。F-net、China Digital Seismograph Network(CDSN)、Global Seismograph Network (GSN) の観測点を使用した。
得られた位相速度の分散曲線から、2 観測点間の平均的な 1 次元 S 波速度構造を遺伝的アルゴリズムを使って推定した。最上部マントル（モホ面から 220 km）は radial anisotropy、それ以外の層は等方性を仮定した。
沖縄トラフのモホ面直下の S 波速度は大陸棚に比べてかなり低く、これはマントルの上昇による部分溶融を示しているのかもしれない。しかし、220 km 付近では沖縄トラフの方が高くなっており、マントルの上昇の源が深くないことを示唆している。このマントルの上昇は、中央海嶺で解釈されているような受動的な流れかもしれない。沖縄トラフの西側では SV 波が SH 波に比べて低速度になっている。しかし、東側ではほぼ同じである。この radial anisotropy は部分溶融の割れ目の形状またはマントル鉱物の選択配向によるものかもしれない。

キーワード: 沖縄トラフ, 背弧拡大, 地震波速度構造, 表面波
Keywords: Okinawa trough, backarc spreading, seismic structure, surface wave

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SIT03-P07

会場:コンベンションホール

時間:5 月 26 日 18:15-19:30

フレンチポリネシア下の P 波速度異常
P-wave velocity anomalies of the plume beneath the French Polynesia
大林 政行 1∗ ; 吉光 淳子 1 ; 杉岡 裕子 1 ; 伊藤 亜妃 1 ; 一瀬 建日 2 ; 塩原 肇 2 ; 末次 大輔 1
OBAYASHI, Masayuki1∗ ; YOSHIMITSU, Junko1 ; SUGIOKA, Hiroko1 ; ITO, Aki1 ; ISSE, Takehi2 ;SHIOBARA, Hajime2 ; SUETSUGU, Daisuke1
11

D-EARTH, JAMSTEC, 2 ERI, Univ. Tokyo
D-EARTH, JAMSTEC, 2 ERI, Univ. Tokyo

The French Polynesian region is characterized by positive topographic anomalies of 700 m, a concentration of hotspot chains.
Many seismic tomography results show a broad low-velocity anomaly in the lower mantle continued from the base of the mantle.
These observations suggest that a large-scale mantle flow rises from the bottom of the mantle beneath the region. Joint JapaneseFrench broadband seismological observations were performed from 2001 to 2005 with 10 island stations from the Polynesian
PLUME project (Barruol et al. 2002) and 10 broadband ocean bottom seismometers (BBOBSs) from the Polynesian BBOBS
project (Suetsugu et al. 2005). A P-wave
tomography using the data from these projects revealed that large-scale low-velocity anomalies (on the order of 1000 km indiameter) from the bottom of the mantle become smaller-scale low-velocity anomalies (on the order of 100 km in diameter) at
the depth of about 1000 km. However the connection of the small-scale low-velocity anomalies to the surface hotspots was notunrevealed because of the poor resolution in the upper mantle.
A new P-wave tomography with better resolution in the upper mantle was obtained by adding data from BBOSBSs aroundSociety Islands deployed along the TIARES project during 2009 - 2010 (Suetsugu et al. 2012) and by taking the finite frequency
effect into account for the frequency-depended differential travel times. The frequencydepended differential travel times weremeasured by multi-band cross correlating P waveforms. The new P-wave tomography shows strong low-velocity anomalies
beneath the Society Islands and Pitcairn in the upper mantle although they do not extend to the 660-km discontinuity. This model
also shows that small-scale low-velocity anomalies in the uppermost lower mantle. The low-velocity anomalies in the depth
range about 550 - 900 km are smaller both in lateral area and amplitude than those in most of the upper mantle and the lowermantle. The velocity patterns are well correlated each other in the depth range but are not correlated with the patterns above andbelow, indicating the mantle beneath the French polynesia can be divided into 3 layers in terns of radial correlation.
キーワード: トモグラフィ, プルーム, マントル, フレンチポリネシア
Keywords: Tomography, Plume, Mantle, French Polynesia

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