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Vol.02 GSA (Geo Space Adventure)

Photon Boy explores an underground world at Kamioka-mine!

The GSA is a science event held every summer at the Kamioka Mine located in the town of Kamioka in Hida-city in Gifu Prefecture. This event was held on July 17 and 18th in 2015. I was lucky enough to take part in GSA 2015 and so I can give you a brief report on what it is all about!

International Year of Light and Light-based technologies

The time when large scale mining dug up ores and minerals from the Kamioka-mine is now over, but the fact that the area has minimal natural background radiation and a large mine shaft space available has brought the mine a comeback in the form of the Astrophysics Experiment Facility. Facilities such as the Kamioka Observatory, operated by the Institute for Cosmic Ray Research at the University of Tokyo are located here and carry out the cutting edge astrophysics research on neutrinos and dark matter, etc.

The Kamiokande Experiment Facility which first started making observations in 1983 is especially famous for a major discovery in 1987 by detecting neutrinos originating from a supernova explosion occurred in nearby galaxy called the Large Magellanic Cloud. This discovery led in 2002 to the awarding of the Nobel Prize in Physics to Koshiba Masatoshi a Distinguished University Professor at the University of Tokyo. If you are someone who likes science, then this is a really special place you don’t want to miss.

So what kind of place is the town of Kamioka?

Kamioka, located in Hida-city in Gifu Prefecture is a quiet castle town that has flourished through the ages from the rich mining there. In the Kamioka-mine area, Mount Ikenoyama where the Mozumi-mine is located stands some 1,369 meters tall along the Takahara River flowing through the center of town. Our underground adventure tour taking place in this mountain is a GSA. If time permits taking a walk through the town of Kamioka is highly recommended.


Kamioka Castle

View of the town area from Kamioka Castle. This photo was taken in April so snow can still be seen along the front side of the mountain.

Called the “Happy junction of 6 roads” in the local area, this is a strange intersection formed in mysterious angles.

Taking part in the GSA 2015 mine exploration tour

We first gathered at the Kamioka town public hall to finish signing up for the tour. Even though it was July and mid-summer, the temperature in the mine is a cool 14°C all year round. That’s why everyone has cold weather jackets.


Kamioka town central public hall serves as our reception area. It is run by volunteer staff from the “GSA Executive Committee” which is mostly made up of citizens from Hida-city.



Boarding the bus next to the town hall. Tour members were a mixed group ranging from elementary school kids to senior citizens. There are 8 bus trips per day and I took part in the earliest group leaving at 7 in the morning.

We set off the microbus and arrived at the Atotsu-mine entrance from where we will enter the huge underground space in the mine. During the bus trip, our tour conductor who was one of the volunteer staff told us the rules to follow while in the mine.

Here we just arrived at the Atotsu-mine entrance along the banks of Atotsu River. We are finally going inside the mine! Even the air was cool here and it felt a little bit cold.

Finally entering the underground world and into Kamioka-mine

Entering Atotsu-mine we next switched to a low-emission vehicle specially made for mine operations. Finally we are going further into the mine. This mine shaft located directly below the peak of Mount Ikenoyama extends 1,000 meters underground. Entering deep inside a mountain by car is an experience most people never get to see.


After moving 1,500 meters horizontally from the Atotsu-mine entrance, we got off the bus. We then walked along the mine passage seen in the next picture.

Along the passage everyone shut off their flashlights to view a startling attraction. We found ourselves surrounded a true jet black world impossible to experience above ground. Suddenly we felt wrapped in a feeling of real adventure!

We reached the Kamioka-mine itself. This mine has a very old history. Digging first started in the Nara Period (8th century in Japan). The mine mainly produced zinc, lead, and silver ore.

A short show is given that recreates the digging during the Edo era (17th to 19th in Japan). The GSA volunteer staff enthusiastically play their roles in this show. (But wait! It looks very cold! Well, even so this is a popular job among the volunteer staff!)

Kamioka-mine and the overwhelming power of heavy drilling machinery!

We next got a description and actual demonstration of heavy-duty drilling equipment from an employee at the Kamioka Mining and Smelting Company. Here we got a close look at heavy machinery that people usually never get the chance to see. Currently there is no large-scale ongoing excavation of metal ores but drilling operations are in progress to expand and build new experiment facilities so this heavy-duty equipment will of course play a major part.


This heavy-duty equipment is called a LHD (load-haul and dump) machine. The back section has been lowered to allow use inside the mine.

Unique experience inside the mine. Sitting in the driver’s seat while also getting a souvenir photo taken -- what a thrill!

Heavy equipment called Jumbo Drill easily drills holes in solid rock for planting dynamite.

We got a live demonstration of the Jumbo Drill. It drills holes in super-hard solid rock in just seconds. Dynamite is then planted in these holes and exploded.

On to Super-Kamiokande for the cutting-edge neutrino research!

After walking back through the mine, we next went to ”Super-Kamiokande” a research facility run by the Institute for Cosmic Ray Research, University of Tokyo. The Super-Kamiokande is an observation device made from a cylindrical tank 40 meters in diameter and at a depth of 41 meters filled with 50,000 tons of pure water. The entire surface on the inner side of the tank is enclosed by devices called photomultiplier tubes each 20 inches (about 50 centimeters) in diameter. These photomultiplier tubes allow observing neutrinos flying here from outer space!


Conceptual image view of Super-Kamiokande. During the GSA, you can observe the top of tank in the experimental area, from the mine passageway.

Lonely mine passageway. The passage and its walls are coated with underground water flow from the mountain. There is plenty of underground water here to supply the pure water to fill into the Super-Kamiokande tank.

We just arrived at the entrance to the Super-Kamiokande experimental laboratory.

Here we are shown a video describing the Super-Kamiokande facility and the experiments performed here. The wall at the rear is crammed with signatures of famous person who visited this facility! This really gives you the feeling that this is a research site attracting attention from all over the world!

Here we tour the ceiling section of the tank. Beneath our feet where we are standing are some 50,000 tons of water and photomultiplier tubes (super-high sensitivity photosensors for detecting elementary particles) and now we are right in the middle of this research. Just thinking about it gives you goosebumps!

Treasured photos from inside the tanks at Super-Kamiokande

Unfortunately, experiments are now underway at Super-Kamiokande which means entering inside the tank or peeking inside is prohibited. But to tell the truth I’ve already been inside the tank! In 2006, I got special permission to enter it during the tank maintenance period. Take a look at some of the pictures I took at that time.


Here is a picture from right inside the Super-Kamiokande tank! It is a long way down, very deep, and yes, very scary! The water level was very low at this time, only about 2 meters or roughly seven feet.

The photomultiplier tubes are densely set into the walls of the tank. Each of the tubes is 20 inches in diameter (about 50 centimeters), so you can get some idea about how big this space is can’t you?

The bottom of the tank. Countless photomultiplier tubes set in the walls are reflected in the clear water. It is very mysterious and wonderful.

A teacher from Tokyo University gave a presentation on neutrinos at the GSA. Here I finally found out the reason we couldn’t open the tank and look inside. The teacher will answer any questions you want to ask. It was really interesting and I learned a lot.

End of the GSA tour

Once the tour inside the mine finished, we returned by shuttle bus to the Kamioka town public hall. Inside the town public hall, we saw a presentation of “kamLAND” which is a separate observation facility within the mine. There were also displays and exhibits by the Kamioka Mining and Smelting Company that operates the mine and Hamamatsu Photonics that produces the photomultiplier tubes used at Super-Kamiokande. Here we got actual close-up views of valuable minerals as well as photomultiplier tubes and many other unusual items.


Leaving the mine and going back outside the mountain by the custom mine transport vehicle.

Here you can buy various kinds of souvenirs on sale including goods such as official helmets, work gloves, flashlights and parkas clearly bearing the GSA logo as well as “black dark manju” ”mine manju” which are buns filled with different flavored bean jam, ”red loincloth noodle” and ”black dark noodle.” These are all popular favorites!

On the way home we got a view of the Nishizato Bridge at dusk. Kamioka castle stands in the background. Wow! It was fun day packed with sights and thrills!

Check out these other websites for more detailed information on GSA and Super-Kamiokande, etc.

GSA [GEO SPACE ADVENTURE] http://gsa-hida.jp/ *Japanese
Institute for Cosmic Ray Research at the University of Tokyo, Kamioka Observatory http://www-sk.icrr.u-tokyo.ac.jp/index-e.html
Hida-city http://www.city.hida.gifu.jp/ *Japanese
Hida Academy http://www.hida.academy/index.html *Japanese