1:45 PM - 3:15 PM
[O11-P62] The rope lava’s directions reveal where Anei lava hills locate
Keywords:Rope lava, Anei Lava Hill, Izu Oshima
The rope lava’s directions reveal where Anei lava hills locate
OBJECTIVES
We went to Izu Oshima Island to do fieldwork. While walking around the Anei Lava Hills, we found a strange lava. The lava had two wrinkles facing in opposite directions. We then investigated other lava formations in the surrounding area and tried to clarify the formation process of the lava with two opposite directions of creases.
About the Anei Lava
As the name suggests, this hill group was formed during the Anei period of the Edo period (1603-1868). And this lava hill group is characterized by the fact that it was formed by the eruption of lava flow from the northwestern foot of Mt.
Survey Methods
The following five items were investigated.
Location: A map (red three-dimensional map) showing the location of the lava flow with the lava in front of us was used to confirm the location of the lava flow.
Flow and direction: A smartphone equipped with an application that can measure inclination and direction was placed parallel to the lava and used to take measurements.
Total length: We measured the length of the convex part of the lava in the forward direction and the convex part in the tail direction using a tape measure or a folded tape measure.
Number of wrinkles: We counted the convexity of the lava as far as we could see.
In this way, we were able to measure a total of 37 lava flows, including retrograde lava flows.
Results
We found that the lava flowed from top to bottom along the slope of the lava hill. On the other hand, lava located on a relatively flat area (here, we positioned it as an area that was not overtly a slope of a lava hill when we actually saw it with our eyes or when we looked at it on the red three-dimensional map), the direction of flow was not consistent. Lava with a retrograde crease is also included in the lava on this side of the map.
Discussion
At first glance, lava located in a relatively flat area appears to be inconsistent. However, even flat areas have slight differences in elevation, which may affect the consistency of the lava. We thought that the retrograde lava may have been formed due to this difference in elevation.
After the fieldwork, we continued to study the Anei Lava Hills, consulting materials and experts on the subject. As a result, we learned that some studies have already shown the formation process of the hills and that lava from the cracks of the lava mounds formed rope-shaped lava. However, we were unable to find any reference to the number and extent of such lava mounds. Our fieldwork and the red three-dimensional map show visually that there were at least 20 small lava flows on the surface of one lava hill.
Future Prospects
After our fieldwork on Izu Oshima, we further focused our attention on an old map called “Anei no Eruption Ezu” (Map of the Eruption of Anei). This map was found at the Oshima town hall around 1917, and although the author and date of production are unknown, it depicts the great eruption of Anei in the overall map of Izu Oshima. However, it is believed to have been drawn after 1800, after the port was completed, since the port is connected to the sea and there are boats floating in the bay. In this old map, what seems to be the Anei Lava Hill Group is described. In the future, we would like to expand the scope of our survey of the lava rope and clarify its relationship to this old map.
OBJECTIVES
We went to Izu Oshima Island to do fieldwork. While walking around the Anei Lava Hills, we found a strange lava. The lava had two wrinkles facing in opposite directions. We then investigated other lava formations in the surrounding area and tried to clarify the formation process of the lava with two opposite directions of creases.
About the Anei Lava
As the name suggests, this hill group was formed during the Anei period of the Edo period (1603-1868). And this lava hill group is characterized by the fact that it was formed by the eruption of lava flow from the northwestern foot of Mt.
Survey Methods
The following five items were investigated.
Location: A map (red three-dimensional map) showing the location of the lava flow with the lava in front of us was used to confirm the location of the lava flow.
Flow and direction: A smartphone equipped with an application that can measure inclination and direction was placed parallel to the lava and used to take measurements.
Total length: We measured the length of the convex part of the lava in the forward direction and the convex part in the tail direction using a tape measure or a folded tape measure.
Number of wrinkles: We counted the convexity of the lava as far as we could see.
In this way, we were able to measure a total of 37 lava flows, including retrograde lava flows.
Results
We found that the lava flowed from top to bottom along the slope of the lava hill. On the other hand, lava located on a relatively flat area (here, we positioned it as an area that was not overtly a slope of a lava hill when we actually saw it with our eyes or when we looked at it on the red three-dimensional map), the direction of flow was not consistent. Lava with a retrograde crease is also included in the lava on this side of the map.
Discussion
At first glance, lava located in a relatively flat area appears to be inconsistent. However, even flat areas have slight differences in elevation, which may affect the consistency of the lava. We thought that the retrograde lava may have been formed due to this difference in elevation.
After the fieldwork, we continued to study the Anei Lava Hills, consulting materials and experts on the subject. As a result, we learned that some studies have already shown the formation process of the hills and that lava from the cracks of the lava mounds formed rope-shaped lava. However, we were unable to find any reference to the number and extent of such lava mounds. Our fieldwork and the red three-dimensional map show visually that there were at least 20 small lava flows on the surface of one lava hill.
Future Prospects
After our fieldwork on Izu Oshima, we further focused our attention on an old map called “Anei no Eruption Ezu” (Map of the Eruption of Anei). This map was found at the Oshima town hall around 1917, and although the author and date of production are unknown, it depicts the great eruption of Anei in the overall map of Izu Oshima. However, it is believed to have been drawn after 1800, after the port was completed, since the port is connected to the sea and there are boats floating in the bay. In this old map, what seems to be the Anei Lava Hill Group is described. In the future, we would like to expand the scope of our survey of the lava rope and clarify its relationship to this old map.