Sedimentary rocks record physico-chemical conditions of the Earth’s past surface environment. Therefore, analyses of sedimentary structures and geochemistry of clastic rocks enable unraveling the environmental changes of the past Earth. By analyzing such records, we tackle to reveal the sedimentary environment and paleoclimate of the Japanese Islands, and further to assess evolutional histories of the Eastern Asian region. The main analytical methods employed in our laboratory include XRF, XRD, EPMA, CL and ICP-AES analysis as well as basic geological field researches.

　Japan is one of the most famous volcanic countries in the world. Volcanoes fascinate people with their beautiful landscapes and dynamic eruptions and provide benefits such as hot springs and mineral deposits, but they sometimes cause major disasters. Therefore, research on volcanoes is carried out with an awareness of its application to disaster prevention and mitigation. What makes our research laboratory unique compared to other laboratories is that our main research targets are young geological bodies (volcanic bodies) formed since hundreds of thousands of years ago, and ongoing geological phenomena (eruptions) are also included in the research. The time scale of these phenomena is short, with typical volcanic lifespans of several hundred thousand years, with volcanic activities lasting a few years, and with single eruptions lasting from several hours to several minutes.
　The eruptive phenomena observed on the earth's surface are diverse in terms of scale, style, and duration, etc., and it changes even in a single volcanic activity or in the life of a volcano. In order to explore the underlying mechanism, it is essential to clarify the structure of the underground magma supply system and the magma process. The volcanic rock formed by magma erupting onto the surface and rapid cooling have records of the history of magma generation, evolution in magma chambers, and migration of magma to the surface at the time of eruption, along with information on their time scales. The main theme of our laboratory is to decipher these volcanic rocks, "letters from underground," and to understand the mechanisms of diverse eruptive phenomena, eruption triggering processes, and the development history of volcanoes.
　In addition to the petrological methods, we also value the methods of volcanic geology. The layers of geological strata and lava flows left behind by each eruption provide clues to the temporal change of past volcanic activities (eruption style and scale) and the eruption history of a volcano after the birth. In other words, basic data on volcanic geology are essential for conducting meaningful petrological studies. It is believed that each volcano has own characteristics in style of volcanic activity, so exploring the past eruptions is extremely important for predicting the characteristics of future eruptions.
　

Eruption at Showa crater of Sakurajima volcano (July, 2013) . 　

The earliest erupted magma in the 2011, Shinmoe-dake eruption
(a fragment in Jan 19 ash).

The ammonite pavement in the lower Jurassic Blue Lias in Lyme Regis.

Belemunitella americana from the Pee Dee Formation, South Carolina, USA. The international reference standard for stable carbon and oxygen isotopes, PDB, was made from the same species of belemnite fossils from the Pee Dee Formation.

　We humans have only reached the depth of a thin layer from the Earth's surface and still do not fully understand the Earth's interior better than other planets. How can we study the interior of our planet? In our laboratory, we conduct high-pressure experiments using various high-pressure apparatuses to reproduce high-pressure and high-temperature conditions equivalent to the deep Earth (crust, mantle, and core). The main goal is exploring phenomena occurring in the unreached depths and elucidating the inner structure and evolution of the Earth and other terrestrial planets.
　We experimentally investigate changes in the crystal structures and physical properties, and chemical reactions of analogue materials (such as minerals and metals) in the Earth's and planetary interiors under high pressure and high temperature conditions (in the range of ‾GPa and several thousand Kelvin). Using in-situ observations via multi quantum beams (synchrotron X-ray and pulsed neutron) and spectroscopy methods (Raman and infrared absorption) combined with chemical analyses of recovered samples, we are especially focusing on the behavior of water (hydrogen) transported to the deep Earth and noble gases that are depleted in the Earth's interior. It is essential to integrate various fields beyond geochemistry for unveiling the Earth's mystery, we are actively involved in the collaborative research working with other universities and research institutes.

Figure 1：Diamond anvil cell (DAC) and silicate sample loaded into its chamber.

Figure 2：Setup for high-pressure and high-temperature neutron experiments and the result of elemental mapping of the recovered sample.

　We aim to understand macroscopic phenomena by elucidating the structure of materials on the Earth surface and their formation mechanisms. Electron microscopy and other microstructural analytical techniques are the main tools used in our research (Fig. 1).
　One of our recent research topics is elucidation of biomineralization mechanisms and its applications. Organisms often utilize inorganic materials (biominerals) as their hard tissues like bone, teeth, exoskeleton, shell, scale, etc. It is well known that our bone and teeth are made of calcium phosphates (e.g., hydroxyapatite) with organic matrices. On the other hand, shell of mollusks, exoskeleton of crustacean, eggshell, and otolith are made of calcium carbonate. These hard tissues often exhibit excellent properties to sustain the activity of the organisms, which are generally originated from well regulated micro- (or nano-) structures (crystalline phase, size distribution, morphology, defect, crystal orientation) of the biominerals in the tissues. Another characteristic of the biominerals is that they are formed in environments where organisms live, i.e., at ambient temperature and pressure, and relatively in a short time, which is largely different from minerals in rocks. This means that kinetics often play an important role with thermodynamics (Fig. 2). The formation and regulation mechanisms of biominerals have been investigated for a long time, but still not well understood.
　It is known that most biominerals nucleate on organic matrices which may regulate the crystal orientation and possibly crystalline phase, and they grow in solutions incorporating organic molecules secreted from the organism. These intracrystalline organic molecules may also influence the structure of biominerals. We are investigating the roles of these organic matrices and intracrystalline molecules in the formation processes of biominerals, by analyzing fine structures in the hard tissues mainly using electron microscopy, and by conducting in vitro experiments of crystal growth. The research of biominerals is definitely an interdisciplinary science. We often collaborate with other laboratories with different methodologies to advance the research.

Figure 1：Transmission electron microscope capable of observing materials at the atomic level.

Figure 2：One of the otoliths, called asteriscus, found in the head of a salmon. It is composed of vaterite, a calcium carbonate crystal that is rarely found in the Earth’s environments.

　I specialize in metamorphic petrology with a particular research focus on the petrogenesis and exhumation process of high-pressure type metamorphic rocks such as eclogites. The strength of our research group lies in combining geological observations with quantitative petrological, Raman spectroscopic and mineralogical approaches in metamorphic rocks to understand the geochemical and geodynamic processes at subduction zones from the mineral’s nanometer scale to the plate tectonic scale. Principally we have performed laboratory-based investigations on metamorphic rocks from the southwest Japan (Sanbagawa belt), eastern China (Sulu UHP terrane), and others. 　

Eclogite-facies bodies from the Sanbagawa belt of southwest Japan.

　"What should we understand the earth is like?" Humans have been facing this question for a long time. Ancient people thought that the earth was flat. Around the 6th century B.C., however, they came to think that the earth was a sphere. When a ship appeared from beyond the horizon, the top of the ship would first be visible, and then the entire would gradually appear. The shape of the earth would be estimated based on such observations.
　The study of the shape of the earth (and also other planets, asteroids, or satellites in the solar system), including shape, rotation, gravity, natural environment, and those time variabilities based on observations is called "geodesy" in the modern academic world. Geodesy using space technology is called "space geodesy," and especially when using artificial satellite data, it is called "satellite geodesy".
　This laboratory is mainly engaged in satellite geodesy. We use artificial satellite data to investigate the shape, rotation, gravity, and natural environment of the earth and those time variabilities. Artificial satellites observes some physical quantities on the earth, such as positions on the ground, temperature, gravity, and so on, and data analysis is mainly based on statistics. So, statistical analysis of some terrestrial physical quantities observed by artificial satellites characterizes our researches.
　Here is an interesting example. Two figures shown below indicate the results of the analysis of gravity data around Japan observed by satellite gravimetry. These results are based on principal component analysis. If you do not know the details, you can see that the gravity around Japan has been changing co- and post-seismically related to the 2011 off the Pacific coast of Tohoku earthquake. In Figure 1, you can see the post-seismic gravity changes, and in Figure 2, you can see the coseismic gravity changes. The amounts of these changes are so small that humans cannot sense them and they do not affect our daily lives.

Figure 1：First principle component (60.1%) of the gravity changes.

Figure 2：Second principle component (23.5%) of the gravity changes.