箱根火山群 - 駒ヶ岳 - Hakone Volcanic Group - Komagadake - 3/26/2025

Hakoneyama, Kamiyama, & Komagadake from looking from south in Ryuguden Honkan Parking on late afternoon of 3/26/2025

My Experience: My very first trip to this area was March 24 & 25 of 2016 however I took that train back then and my visit was more on the North side of Hakoneyama to the spa (onsen) town of Gora. In fact, I would also say this was my very first onsen experience.

Although 9 years ago this was, it feels like 20 as so much has past in terms of lost love, parent that have passed on, several career/job changes, multiple house/location changes from San Francisco Bay Area, to San Diego, and now LA...

...and now, 9 years later, I have returned but this time to hike, and this time with a van, and this time more concretely tied to a country and an experience I thoroughly love and enjoy.

A significant other from a former relationship once told me, "you will never be accepted in Japan, you will always be an outsider, always a foreigner"...and in some ways I do feel that, I feel a coldness, and a bit of a barrier (likely mostly also because of my limited fluency with the language) but I also wonder how much of that is also me and interpretation. Conversely, I can also say out of all my experiences throughout life some of my most magical and seemingly god-like experiences, have also been here (in Japan).

But, back to Hakoneyama...

I am now rounding out a second trip in less than 6 months, spending 2 months here this trip. In my last week on 3/26, I drove from Takasaki (in Gunma) to the point of which I thought that I would start the hike Hakone-en Fuji Ashinoko Panorama Park Parking Lot

富士芦ノ湖パノラマパーク駐車場 however due to severe traffic which took me 4.5 hours to arrive and a parking lot that closes at 430 PM, I decided to park further down the road closer to the trailhead in a very tiny gravel space that only fits maybe 4 vehicles around here: https://maps.app.goo.gl/au2wzjWKicvN31v38 given I was worried about being locked-in the other parking lot since I was starting hike late.

Anyway, all that said, if you have even cared to read this far, I was able to make it up Komagadake to the ropeway and back down in only 2 hours and 15 minutes. Here is my route on AllTrails: https://www.alltrails.com/explore/recording/afternoon-hike-0b33f2e-761

Note: there is a bit of a tricky spot. There is one trail segment that notates to the shrine AND you will see plenty of people walked that way but it also puts you on the other side of a roped off was that does not say DO NOT ENTER until you are on the other side. I accidentally walked across this area. It was not clear to me as I was just following boot prints from others. TIP: walk on outside of rope

Anyway, once completed, I reached the top, saw the shrine, alot of westerns tourist (ALOT), had taken the ropeway up...I turned around and started down the mountain pretty much jogging down. The conditions were very muddy as well but made it down quickly. I could not hike over to Hakoneyama or Kamiyama because the trail was closed as a result of volcanic gases.

Youtube Video coming soon - usually takes me a month after to start generating the videos from the trip. If you have questions, please feel free to reach out to kazan@volcanicjapan.com

Demographics

Volcano No. - F04

Volcano name - Hakone Volcano Group

Geologic code **Q3m

Main activity period - Chibanian (Middle Pleistocene) - Holocene

Activity period / recent activity ***From 0.65 Ma.

Latest eruption - AD 2015

Volcano type - Composite (compound) volcano - Caldera, Lava flow, Composite (compound) volcano, Lava dome

Representative rock type - Intermediate

Main rock type - Andesite, Basalt, Dacite

Height above sea level - 1438 m (Kamiyama)

Location (Prefecture) - KANAGAWA - N. Latitude (WGS84)35.2333 - E. Longitude (WGS84)139.0208

Active volcano name by JMA - Hakoneyama

Record of eruption & disaster - 29 Jun - 1 Jul 2015: Very minor phreatic eruption (Owakudani): : Ash fallout; lahar. Several craters (maximum diameter is ca. 20 m) and fumaroles were formed in the narrow area of ca. 150m in length.

Additional comments - Hakone Volcano is an active volcano.

Source: Geological Survey of Japan

About

Mount Hakone (箱根山, Hakoneyama), with its highest peak Mount Kami (1,438 meters), is a complex volcano in Kanagawa Prefecture, Japan that is truncated by two overlapping calderas, the largest of which is 10 × 11 km wide. The calderas were formed as a result of two major explosive eruptions about 180,000 and 49,000–60,000 years ago. Lake Ashi lies between the southwestern caldera wall and a half dozen post-caldera lava domes that arose along a southwest–northeastern trend cutting through the center of the calderas. Dome growth occurred progressively to the south, and the largest and youngest of them, Mount Kami, forms the high point of Hakone. The calderas are breached to the east by the Haya River canyon. Mount Ashigara is a parasitic cone.

The latest magmatic eruptive activity at Hakone occurred 2,900 years ago. It produced a pyroclastic flow and a lava dome in the explosion crater, although phreatic eruptions took place as recently as the 12–13th centuries AD.

According to the nearby Hakone Shrine, the Komagatake peak has been the object of religious veneration since ancient times.

History - The geological history of Mount Hakone, has been researched by Dr. Hisashi Kuno et al., with Mount Hakone, located in Hakone, Kanagawa, Japan, as a volcano from the Quaternary period.

Mount Hakone started about 500,000 years ago with the eruptions, that created Mount Kintoki and Mount Myōjō on the current "Old outer rim"; and the subsequent eruptions about 160,000 years ago made the "New outer rim", on which are Mount Sengen and Mount Takanosu (Kanagawa).

From 50,000 years ago, new eruptions further created in the "Central volcanic cones" Mount Kami (35.233333°N 139.020556°E), the highest peak in Hakone, Mount Koma and other peaks; and about 300,000 years ago, the lava domes such as Mount Futago emerged.

Later about 3,000 years ago, the phreatic eruption on the northwest side of Mount Kami caused landslides, creating the Owakudani and, in the huge caldera, the Sengokuhara and Lake Ashi.

Hakone (generalized "the town" or area) (箱根町, Hakone-machi) is a town in Kanagawa Prefecture, Japan. As of 1 October 2023, the town had a population of 10,965, and total area of 92.82 km2 (35.84 sq mi).

Hakone is a notable spa town and a popular tourist destination due to its many hot springs being within view of nearby Mount Fuji, the most visited mountain in Japan.

Geography

Hakone is located in the mountains in the far west of the prefecture, on the eastern side of Hakone Pass. Most of the town is within the borders of the volcanically active Fuji-Hakone-Izu National Park, centered on Lake Ashi.

Economy

The economy of Hakone is strongly dominated by the tourist industry. Hakone is noted for its onsen hot spring resorts, which attract both Japanese and international visitors, due to its proximity to the greater Tokyo metropolis and to Mount Fuji. Sights include the volcanically active Ōwakudani geysers and Hakone Shrine on the shore of the lake, as well as the Hakone Botanical Garden of Wetlands. In April the cherry blossoms (sakura) and in autumn the Miscanthus sinensis (susuki) are noted sights.

Hakone has a number of art museums, including the Hakone Open-Air Museum and Pola Museum of Art.

Major events include the annual JLPGA CAT Ladies Golf tournament and the Hakone Ekiden, a long distance collegiate foot race, held at the New Year, which runs from Tokyo to Hakone and back over two days, partly in commemoration of the couriers who ran the Tōkaidō road.

One famous hotel in Hakone is the historic Fujiya Hotel in Miyanoshita, which was patronized by noted literary figures, politicians and foreign dignitaries in the Meiji, Taishō, and early Shōwa eras.

A noted local handicraft is a kind of marquetry called Yosegi.

Hakone is also well known among anime fans for being the main location in the manga and anime series Neon Genesis Evangelion, in which it has been renamed Tokyo-3, and there are numerous attractions related to the franchise offered in the town. In 2017, Hakone was included as one of 88 anime pilgrimage sites for 2018 by the Anime Tourism Association. In 2020, new decorations were introduced to the city in the anticipation of the release of the final film of the Rebuild of Evangelion tetralogy. Source: Wikipedia (Mount Hakone) and (Hakone)

Geological Summary

The Hakoneyama volcano includes large calderas, post-caldera domes, and active thermal areas about 80 km SW of Tokyo. Phreatic explosions have been radiocarbon dated to the 12th or 13th centuries CE, and periodic seismic swarms have been recorded since the late 20th century when regular monitoring began. Renewed activity at the Owakudani hot spring area (1 km N of the Kamiyama dome summit), including two small explosions and the formation of several new fumaroles, was reported by the Japan Meteorological Agency (JMA) in 2015. The area is a popular resort destination with golf courses, spas, skiing, and aerial tramways.

Seismic swarms were previously reported in 1991 (BGVN 16:04), 2001, 2011, and 2013. A slight inflation of the volcanic edifice was recorded between December 2012 and March 2013. Increased seismicity and intense steam emissions at Owakudani were observed beginning in April 2015, and on 29 and 30 June 2015 two small explosions from a new fumarole created a mound of ash around the vent and scattered ash a few hundred meters N. Additional ash was observed in the early morning of 1 July. Strong degassing from the fumaroles continued through the end of the year, although seismicity dropped below detection by mid-August, and inflation stopped at the end of August.

Activity during 1991-2014. A swarm of about 300 earthquakes, all less than M 2.5 and located at 5 km depth below the central part of the caldera, was reported by JMA in April 1991 and felt by area residents (BGVN 16:04). Between June and August 2001 elevated seismicity from depths less than 5 km below the surface was associated with a small amount of inflation centered at the volcano; a small swarm was also recorded under the N end of Ashino-ko (Lake Ashi).

A brief period of increased seismicity was again recorded in the few days following the 11 March 2011 Tohoku Earthquake which was centered about 400 km NE. The activity was confined to the area around the Owakudani hot springs. On 21 March 2011, a M 4.2 earthquake occurred around the Komagatake dome (1 km SSE of Kamiyama). Fumes from the Sounjigoku geothermal area on the E side of the volcano were observed rising 50-200 m during March 2011. The tiltmeter network operated by the Hot Springs Research Institute of Kanagawa Prefecture showed no relevant changes resulting from the earthquake.

Activity during 2015. Scientists conducted field surveys on 4-5 April 2015 and observed forceful steam emissions at the Owakudani hot spring complex that continued at least through 8 April. Six small seismic events were recorded on 10 April in the Yumoto area of the city of Hakone (8 km ESE). JMA reported an increased seismicity to tens of daily events at Hakoneyama beginning 26 April 2015. On 5 May, three more small seismic events were recorded in the Yumoto area. This led JMA to raise the Volcano Alert Level from 1 (Normal) to 2 (Do not approach the crater) on a 5-level scale on 6 May. There were 21 additional small seismic events in the Yumoto area during May 2015. The daily total of all seismic events rose significantly to 442 on 15 May, the highest since 2001.

Ground deformation data showed changes attributable to the seismic events. The Mainichi (a daily newspaper) reported on 17 May 2015 that an analysis of satellite data by the Geospatial Information Authority of Japan found that the ground level in a 200-m-diameter area in the Owakudani district rose 12 cm between 17 April and 15 May. Intense steam emissions continued at the Owakudani hot spring supply complex in May.

Volcanic tremor lasting for around five minutes started at 0732 on 29 June 2015. At around 1245, fallout was observed in an area up to 1.2 km N and NE of the Owakudani hot spring complex. This fallout was interpreted by JMA to be sediment and debris ejected from a "blowhole" that formed a new fumarole at Owakudani. A field survey conducted on 30 June observed a mound of volcanic ash around the new fumarole. Additionally, volcanic ash was observed near the Owakudani Station of the Hakone Ropeway (a resort tramway) located about 300 m NNW of the hot springs area. As a result of the discovery of the ashfall, JMA raised the Alert Level at 1230 on 30 June from 2 to 3 (Do not approach the volcano).

Additional volcanic ash was found on a camera around 0500 on 1 July. Air shocks that were intermittently observed from 1600 on 29 June to 1 July may have occurred in association with eruptions, the last occurring between 0400 and 0500 on 1 July. A field survey conducted by the Hot Springs Research Institute of Kangawa Prefecture and JMA on 2 July confirmed continued forceful emissions of steam at the new fumarole, which had grown to 20 m in diameter, and was designated Crater 15-1. Three other new fumaroles were also observed around this crater.

No low-frequency earthquakes or volcanic tremors were recorded in July, but active degassing at Crater 15-1 and adjacent fumaroles continued. In a field survey on 6 August 2015, material described as "dark gray soil" was observed around the fumarole, inside the crater rim. Thermal infrared observation showed a high-temperature area on the E side of the crater from August through October. A single, minor seismic event was recorded on 17 August, the first one since 3 July. JMA downgraded the Alert Level at the volcano from 3 (Do not approach the volcano) to 2 (Do not approach the crater) on 11 September, and no further changes in the tiltmeter or strainmeter data were observed after August.

Field surveys on 3 and 29 September indicated that "dark gray soil" continued to be ejected from Crater 15-1, but the scale of the explosions were small and ejection heights were lower than the crater rim. Strong degassing was still occurring at the crater and all other fumaroles. By 20 November the slight weakening of the emissions from Crater 15-1 and overall stability and low seismic activity led JMA to reduce the Volcanic Alert Level further to 1 (Potential for increased activity). Field observations on 7 and 9 December 2015 confirmed continuing strong degassing with plumes to 600 m in the area around Owakudani, but no new ejecta.

Geological Summary. Hakoneyama volcano is truncated by two overlapping calderas, the largest of which is 10 x 11 km wide. The calderas were formed as a result of two major explosive eruptions about 180,000 and 49,000-60,000 years ago. Scenic Lake Ashi lies between the SW caldera wall and a half dozen post-caldera lava domes that were constructed along a NW-SE trend cutting through the center of the calderas. Dome growth occurred progressively to the NW, and the largest and youngest of these, Kamiyama, forms the high point. The calderas are breached to the east by the Hayakawa canyon. A phreatic explosion about 3000 years ago was followed by collapse of the NW side of Kamiyama, damming the Hayakawa valley and creating Lake Ashi. The latest magmatic eruptive activity about 2900 years ago produced a pyroclastic flow and a lava dome in the explosion crater, although phreatic eruptions took place as recently as the 12-13th centuries CE. Seismic swarms have occurred during the 20th century. Lake Ashi, along with the thermal areas in the caldera, is a popular resort destination SW of Tokyo.