1:45 PM - 3:15 PM
[O11-P78] Estimating the location of magma rising in volcanic regions
Keywords:Volcano, Usu, disaster, disaster science, Volcanic Disaster Prevention
1. Background and Objectives
The 2000 eruption of Mt. Usu began on March 31, 2000, with an eruption from the western foot of the mountain.The volcano continued to erupt, forming a group of craters, but in May of the following year, a declaration was made that magma activity had ended.
We thought that a sudden volcanic eruption would have a great impact on people, and we thought that if we could find the crater before the eruption, we could limit the damage. Therefore, we began research, thinking that if we could measure the center of the magma, we would be able to find the crater more easily.
2. Research Methods
In previous research, we had only been able to obtain results from data obtained from measurements taken during the Usu Volcano field trip, but we were only able to measure data along the walking trail, and the number of measurements was limited, and the orthogonal lines described below were not facing towards the center, so we decided to increase the amount of measurement data. However, Usu is far from our school and not a place we can visit frequently, so we struggled to increase the amount of data. For this reason, we received the cooperation of Mr. Eiichi Abe of Muroran Sakae High School in Hokkaido, and were given topographical maps of the area before and after the eruption. We thought that by using these topographical maps to take measurements, we would be able to obtain data without having to go to the area, and so we developed this research.
The specific method is as follows.
1) Find a place where the contour interval is exactly 1 cm, and measure the horizontal distance.
2) The more contours there are in a 1 cm interval, the higher the elevation. → Slope measurement
3) Draw strike lines parallel to the contour lines.
4) Determine the strike and dip at each point (illustrated on the poster).
5) Repeat steps 1) to 4) above at multiple points on both the pre-eruption and post-eruption maps (30 points each in this case).
6) Using the Blender app, which allows you to create 3D images, draw the normal at the point where the strike line and dip intersect.
The hypothesis of this research is that the direction of the normal vector indicates the direction of the center of the volcano (the place where magma rises; the magma reservoir), and the above method was used to estimate the place where magma rises.
3. Research Results
When the normal vector was drawn based on the measurement data on the 3D map, it was thought that it would be concentrated to some extent, but in the end it could not be said that it was concentrated in the center.
However, the characteristics of Usu Volcano based on previous research are
(1) As Usu is a stratovolcano and a group of lava domes that formed on the southern wall of the Toya Caldera about 10,000 to 20,000 years ago, its magma chamber is relatively large compared to shield volcanoes.
(2) The depth of the magma chamber at Usu is about 15 km.
Therefore, if we draw longer normals on the 3D map, we can conclude that the normals intersect at the center of the magma chamber, i.e. the center of the magma ascent area.
4. Discussion and future prospects
Compared to our previous research, the data we have gathered for this study has increased, making it easier to estimate the location of the magma chamber. However, we have hit a wall in our attempts to create a 3D model using data from before the eruption, and we have only been able to measure data after the eruption. We are currently exploring various methods to try to create a 3D model using the data that exists from before the eruption, and we are considering comparing the data before and after the eruption.
The validity of this research method cannot be asserted based on research carried out on Mt. Usu alone, but if similar results are obtained for other volcanoes, the validity of the method will be established, and we would like to continue our research so that it can be applied to a wider range of volcanoes. Furthermore, if it is possible to measure and create 3D models of both the pre-eruption and post-eruption phases, it will be possible to illustrate the magma ascent field for the entire Usu region, and we believe that this will contribute to “prior disaster prevention” for volcanic disaster prevention for Mt. Usu eruptions, which recur in a 20-30 year cycle.
The 2000 eruption of Mt. Usu began on March 31, 2000, with an eruption from the western foot of the mountain.The volcano continued to erupt, forming a group of craters, but in May of the following year, a declaration was made that magma activity had ended.
We thought that a sudden volcanic eruption would have a great impact on people, and we thought that if we could find the crater before the eruption, we could limit the damage. Therefore, we began research, thinking that if we could measure the center of the magma, we would be able to find the crater more easily.
2. Research Methods
In previous research, we had only been able to obtain results from data obtained from measurements taken during the Usu Volcano field trip, but we were only able to measure data along the walking trail, and the number of measurements was limited, and the orthogonal lines described below were not facing towards the center, so we decided to increase the amount of measurement data. However, Usu is far from our school and not a place we can visit frequently, so we struggled to increase the amount of data. For this reason, we received the cooperation of Mr. Eiichi Abe of Muroran Sakae High School in Hokkaido, and were given topographical maps of the area before and after the eruption. We thought that by using these topographical maps to take measurements, we would be able to obtain data without having to go to the area, and so we developed this research.
The specific method is as follows.
1) Find a place where the contour interval is exactly 1 cm, and measure the horizontal distance.
2) The more contours there are in a 1 cm interval, the higher the elevation. → Slope measurement
3) Draw strike lines parallel to the contour lines.
4) Determine the strike and dip at each point (illustrated on the poster).
5) Repeat steps 1) to 4) above at multiple points on both the pre-eruption and post-eruption maps (30 points each in this case).
6) Using the Blender app, which allows you to create 3D images, draw the normal at the point where the strike line and dip intersect.
The hypothesis of this research is that the direction of the normal vector indicates the direction of the center of the volcano (the place where magma rises; the magma reservoir), and the above method was used to estimate the place where magma rises.
3. Research Results
When the normal vector was drawn based on the measurement data on the 3D map, it was thought that it would be concentrated to some extent, but in the end it could not be said that it was concentrated in the center.
However, the characteristics of Usu Volcano based on previous research are
(1) As Usu is a stratovolcano and a group of lava domes that formed on the southern wall of the Toya Caldera about 10,000 to 20,000 years ago, its magma chamber is relatively large compared to shield volcanoes.
(2) The depth of the magma chamber at Usu is about 15 km.
Therefore, if we draw longer normals on the 3D map, we can conclude that the normals intersect at the center of the magma chamber, i.e. the center of the magma ascent area.
4. Discussion and future prospects
Compared to our previous research, the data we have gathered for this study has increased, making it easier to estimate the location of the magma chamber. However, we have hit a wall in our attempts to create a 3D model using data from before the eruption, and we have only been able to measure data after the eruption. We are currently exploring various methods to try to create a 3D model using the data that exists from before the eruption, and we are considering comparing the data before and after the eruption.
The validity of this research method cannot be asserted based on research carried out on Mt. Usu alone, but if similar results are obtained for other volcanoes, the validity of the method will be established, and we would like to continue our research so that it can be applied to a wider range of volcanoes. Furthermore, if it is possible to measure and create 3D models of both the pre-eruption and post-eruption phases, it will be possible to illustrate the magma ascent field for the entire Usu region, and we believe that this will contribute to “prior disaster prevention” for volcanic disaster prevention for Mt. Usu eruptions, which recur in a 20-30 year cycle.