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Sakurajima EarthCache

Hidden : 07/19/2012
2 out of 5
2 out of 5

Size: Size:   other (other)

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Geocache Description:

This very active volcano provides an example of geography being changed by geological processes in historical times.

Sakurajima has one of the most active volcanos in Japan and indeed in the world, and has the additional "attraction" of being close to a major population centre. The traces of ash can be found everywhere in Kagoshima. The effects of the volcano on the landscape and the geography have been and will continue to be dramatic.

About 22,000 years ago a caldera with a diameter of 20 km was formed, part of which now forms Kagoshima Bay. Some 9,000 years later a new volcano erupted, forming an island. Later lava eruptions created more islands, which in turn were submerged in greater eruptions. This process continued until recent times, when the islands were actually inhabited, such as during the An'Ei Eruption of 1779. One reason for people taking the risk to live there is that the soil is in many places quite fertile (growing 35 kg radishes, for example).
And it was only in 1914 that an eruption caused Sakurajima to become a peninsula. The most recent major eruption was in 1945.

In Japan, this volcanco is exceptional because of the relatively frequent lava streams. In recent years the activity, mostly in the form of ash plumes, has increased from a level of 80 eruptions per year in 2008 to more than a thousand per year now.

The cache location is in front of Sakurajima Visitor Center (open 9-17h), which is managed by enthousiastic volunteers. The center provides historical information, but also collects information about the volcano's current activity, which you can watch on a seismograph. Opposite the Visitors Center is the impressively named Kirishima-Kinkowan National Park - Hakamogoshi-Karasujima Lava Trail, which is the site of a submerged island, and a good place to take a picture of the smoking South Peak.
From the park you also have a good view of the layout of Sakurajima and of the several peaks of the volcano.

From a long-term perspective, eruptions of this volcano have been of three different types with different time scales. The formation of completely new craters has occurred on a time scale of 10,000 years, or twice so far. There have been major lava flows on a time scale of 50 to a 100 years, with "local" effect, meaning on a scale of several kilometers but not affecting the whole of this huge volcano. And there are ash plumes and small lava flows, on a daily basis and increasing. To log this earthcache, please answer the following questions in a message to the cache owner. Do not put the answers in the log, not even in encrypted form. Please use English if at all possible.

Do you think that it is likely that in the foreseeable future (say a few centuries) an eruption will link Sakurajima to the other side of the bay such as to close off the Northern part thereof from the Pacific Ocean? Please explain.

Look at the number of eruptions from 2008 to 2011. Is there a significant change? Speculate what this could mean for the near future.

Optionally, attach a picture to the log of yourself and/or your GPSr in front of Sakurajima's peaks, preferably during an eruption. Usually you don't need to wait long.










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