Akan-Mashu National Park: nests of volcanoes and calderas
September 8, 2024
You may have visited Crater Lake, Oregon’s only national park. You may know that it is misnamed. A crater is the depression on the top of a volcano where lava and/or pyroclastic materials spew forth during eruptions. But Crater Lake should actually be called Caldera Lake. Calderas are formed when volcanoes are so explosive that they blow off a major part of their ediface to create a huge depression.
Akan-Mashu National Park is filled with calderas. The park was created in 1934—one of the two oldest parks in Hokkaido. It has long attracted tourists who enjoy the lakes, the views, the hiking, the hot springs, and other amenities. The park is in a straight NE-SW line with Shiretoko National Park, as shown on the map in my previous post: https://landscapes-revealed.net/shiretoko-peninsula-japans-end-of-the-earth/. It is a continuation of the Kuril volcanic arc.
Lake / Caldera Kussharo
Lake / Caldera Mashu—”Crater” Lake’s cousin
Lake / Caldera Akan
Lake Akan is another large caldera that has filled in with subsequent volcanic eruptions. If you look at the map above, you can see that the caldera walls (24 x 13 km diameter) surround two smaller lakes, Mt. Oakan, Mt. Meaken and other smaller cones. The Akan Volcanic Complex is a group of stratovolcanoes that grew out of the Akan caldera that formed 31,500 years ago. Its elongated shape is due to formation during several major explosive eruptions.
The highest peaks in the complex are the stratovolcanoes Oakan, Meakan, and Akan-Fuji, one of the many symmetrical Japanese volcanoes named after the reknown Mount Fuji. Meakan (sometimes spelled Me-Akan) is one of the most active volcanoes of Hokkaido and in all of Japan. Its summit contains two active craters that are sites of frequent historical phreatic eruptions, the last one in 2008. Geologic studies have demonstrated that at least four major magmatic eruptions with pyroclastic flows occurred during the past 10,000 years.
After a cloudy day during our visits to Kussharo and Mashu, we were fortunate to have a picture-perfect day to climb Mt. Meakan, a truly spectacular volcano to gaze upon. It was located just a short 15-minute drive from our hotel on the edge of Lake Akan.
Other features
Lake Akan is known for a rare green algae called marimo that can grow to the size of a soccer ball. We saw these marimo algae balls in the Eco-Center along the edge of the lake. Note Jay’s finger for scale.Left-side photo. With all of the active volcanoes in the Lake Akan area, there are, of course, many onsens (hot springs) and our hotel had a wonderful onsen. The edge of Lake Akan a short distance from our hotel is an active geothermal area where the heat immediately melts any snowfall. At the lakeshore, we saw bokke, which comes from “pofuke”, meaning “bubble up” in the Ainu language. A bokke is a mud volcano, where heated mud erupts continuously from an underground vent along with volcanic gases.
Right-side photo. We were still in brown bear habitat, but fortunately the only bears we saw were in the Eco Center.
Hi Karen. Thompson here in SMP on a cold foggy Sunday morning. Just wanted to say hello to you both and tell you how much I enjoyed this particular blog edition. Love all the Caldera versus crater comparisons particularly to crater Lake, which of course we loved when we visited. Plus you included some fantastic photos! And always jealous of all the amazing traveling you guys are doing in your retirement. Speaking of which, Billy and I are leaving in two weeks for Greece for three weeks. Wondering if you have any fantastic geological sites you might recommend we visit while we’re there. We will be in Athens, Crete, Santorini, Naxos, and then driving up to Meteora. Though I believe our hotel in Fiera Santorini looks out over a caldera. Can’t remember if I’ve read a blog edition involving Greece. Happy travels! T&B
Landscapes Revealedon September 9, 2024 at 5:48 am
Thanks Thompson—so good to hear from you! Remembering how you saw my blog and we realized we were in same place in Spain in 2015 and met for dinner! I have been to Athens and Santorini, but in 1989, long before starting the blog. Santorini is a geologic wonder—you will be on the edge of a REALLY large caldera. That eruption, in 1500 BC, is believed to have ended Minoan civilization (in Crete) and had other big effects. Imagine the tsunami and weather changes that would have resulted from something so huge. You’ll probably visit Akrotiri, the archeological site of a town on Santorini that was buried by volcanic ash during the eruption. That’s all the wisdom I can convey. We plan to go to Cyprus next year and plan to add other places—we may need to ask you about Crete. Safe and happy travels! -K
Karen (and Jay),
What an incredible journey you are having! The pictures and background information are fascinating. You guys take such interesting and enriching trips. Very inspiring.
BTW, I’ve dealt with a lot of algae issues in SF Bay, but never saw big balls like that. Crazy!
Hi Karen. Thompson here in SMP on a cold foggy Sunday morning. Just wanted to say hello to you both and tell you how much I enjoyed this particular blog edition. Love all the Caldera versus crater comparisons particularly to crater Lake, which of course we loved when we visited. Plus you included some fantastic photos! And always jealous of all the amazing traveling you guys are doing in your retirement. Speaking of which, Billy and I are leaving in two weeks for Greece for three weeks. Wondering if you have any fantastic geological sites you might recommend we visit while we’re there. We will be in Athens, Crete, Santorini, Naxos, and then driving up to Meteora. Though I believe our hotel in Fiera Santorini looks out over a caldera. Can’t remember if I’ve read a blog edition involving Greece. Happy travels! T&B
Thanks Thompson—so good to hear from you! Remembering how you saw my blog and we realized we were in same place in Spain in 2015 and met for dinner! I have been to Athens and Santorini, but in 1989, long before starting the blog. Santorini is a geologic wonder—you will be on the edge of a REALLY large caldera. That eruption, in 1500 BC, is believed to have ended Minoan civilization (in Crete) and had other big effects. Imagine the tsunami and weather changes that would have resulted from something so huge. You’ll probably visit Akrotiri, the archeological site of a town on Santorini that was buried by volcanic ash during the eruption. That’s all the wisdom I can convey. We plan to go to Cyprus next year and plan to add other places—we may need to ask you about Crete. Safe and happy travels! -K
Karen (and Jay),
What an incredible journey you are having! The pictures and background information are fascinating. You guys take such interesting and enriching trips. Very inspiring.
BTW, I’ve dealt with a lot of algae issues in SF Bay, but never saw big balls like that. Crazy!
Have a great rest of your trip and keep posting!
– Mark and Lynn
We need to meet you again in one of these interesting places, like we did last September! Thanks for reading!