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[MIS25-P02] Possible existence of fissure vent cave in Arsia Mons of the Mars as observed in Miyakejima island
Keywords:fissure vent, volcanic cave, Arsia mons, Miyakejima-island
[Introduction]
The number of lava tube caves is overwhelmingly large as underground cavities in basaltic volcanoes on the earth, but there are also underground craters as crater caves such as pit craters and fissure vents. Komitake hyoketsu No.1,No.2,No.3, Yumiizuka hyoketsu, Kaminari ana), Izu Oshima (C-9 crater cave), Miyakejima (Miyakejima A-3, B-5, B-9 Rift cave), Hachijojima ( It exists in the Eigou Rift cave No.1,No.2,No.3), etc. [1]. The possibility of existence of a similar cave is undeniable for the Mars. Here, the characteristics of the crater cave are introduced by taking the example of Miyakejima, then, the possibility of existence of a similar cave at Mars Arsia mons volcano is examined.
[Miyakejima 1983 Fissure Vent Cave]
The 1983 eruption of Miyakejima caused lava to flow out from the fissure vent [2,3]. The resulting fissure vent cave is a crater formed by magma breaking the scoria layer and rising along the fissure, which is extremely narrow with respect to the crater diameter but deep. The deep structure differs depending on the size of the magma pool and the state of the magma drain back. A thin lava layer (3 to 5 cm) remains on the wall of the vertical hole in the scoria layer, and it is extremely easy to be removed. Many thin layers may be formed on the wall surface due to repeated filling and drain back due to ascent. The depth of the fissure vent cave of Miyakejima formed by the 1983 eruption is 14m to 33m, and the width is several meters. The maximum length of the fissure cavity is 52m [4]. Fig. 1 shows the location of the 1983 lava flow, Fig. 2 shows the location of the fissure vent cave, and Fig. 3, 4 and 5 show the cave cross section, Photo 1 and Photo 2 show the inside of the fissure vent of the cave of A-3 Rift cave, and Photo 3 show the generated minerals [5] attached to the wall surface.
[Vertical hole of Mars Arsia mons volcano]
Several vertical holes have been found on the steep hillsides and skirts of Arcia volcano [6,7]. Estimation of the height of the lava tube cave under the vertical hole (H = 4fB / (ρg sin α)) was performed from the surface slope and the lava yield value of Arsia mons volcano [8]. Where the slope is steep,the thickness of the lava flow is not sufficient to form a large lava tube. The estimated tube height value in the vertical hole of the steep slope of the hillside of Arsia mons volcano (slope angle 1.0 ° to 3.5 °) has a large deviation from the vertical hole depth. Therefore, There is a high possibility of pit crater cave or fissure vent cave. On the other hand, in the vertical hole on the gentle slope of the foot (slope angle 0.12 ° to 0.54 °), the estimated lava tube cave height is almost the same as the estimated tube height, so it is highly possible that a lava tube cave exists [9].
[Conclusion]
Exploration of the internal structure of the vertical hole to clarify what the cavity under the vertical hole of Mars is firstly necessary for understanding the igneous activity. It is expected that the crater cave ,fissure vent cave or the lava tube cave will bring us clear understandings to the lava flow mechanism after the eruption.
References:
[1]T.Ogawa(1988):Dojin,Vol.7,No.3,p69-80
[2]O.Ohshima(1984):Kazan,Vol.29,No.2,p119-120
[3]O.Ohshima(1985):60A,Kazan,Vol.30,No.4,p.322-323
[4]T.Ogawa(1991):The rift caves in Japan,6th International Symposium on Vulcanospeleology 1991,p249-258
[5]T.Sameshima, T.Ogawa, and N.Kashima(1988): 5th International Symposium on Vulcanospeleology,Excursion Guide Book,p75-78
[6] G.Cushing et al(2007):Geophys.Res.Letters,Vol.34,L17201
[7]G.Cushing(2012): CANDIDATE CAVE ENTRANCES ON MARS,Journal of Cave and Karst Studies, April 2012
[8]T.Honda(2017):P117,Fall meeting of 2017 of the Volcanological Society of Japan
[9]T.Honda(2021):MIS12-P02,2021 meeting of JPGU
[10]J.Perala(2015): Pit Craters of Arsia Mons Volcano, Mars, and Their Relation to Regional Volcano-Tectonism, the Department of Earth Sciences, Uppsala University
The number of lava tube caves is overwhelmingly large as underground cavities in basaltic volcanoes on the earth, but there are also underground craters as crater caves such as pit craters and fissure vents. Komitake hyoketsu No.1,No.2,No.3, Yumiizuka hyoketsu, Kaminari ana), Izu Oshima (C-9 crater cave), Miyakejima (Miyakejima A-3, B-5, B-9 Rift cave), Hachijojima ( It exists in the Eigou Rift cave No.1,No.2,No.3), etc. [1]. The possibility of existence of a similar cave is undeniable for the Mars. Here, the characteristics of the crater cave are introduced by taking the example of Miyakejima, then, the possibility of existence of a similar cave at Mars Arsia mons volcano is examined.
[Miyakejima 1983 Fissure Vent Cave]
The 1983 eruption of Miyakejima caused lava to flow out from the fissure vent [2,3]. The resulting fissure vent cave is a crater formed by magma breaking the scoria layer and rising along the fissure, which is extremely narrow with respect to the crater diameter but deep. The deep structure differs depending on the size of the magma pool and the state of the magma drain back. A thin lava layer (3 to 5 cm) remains on the wall of the vertical hole in the scoria layer, and it is extremely easy to be removed. Many thin layers may be formed on the wall surface due to repeated filling and drain back due to ascent. The depth of the fissure vent cave of Miyakejima formed by the 1983 eruption is 14m to 33m, and the width is several meters. The maximum length of the fissure cavity is 52m [4]. Fig. 1 shows the location of the 1983 lava flow, Fig. 2 shows the location of the fissure vent cave, and Fig. 3, 4 and 5 show the cave cross section, Photo 1 and Photo 2 show the inside of the fissure vent of the cave of A-3 Rift cave, and Photo 3 show the generated minerals [5] attached to the wall surface.
[Vertical hole of Mars Arsia mons volcano]
Several vertical holes have been found on the steep hillsides and skirts of Arcia volcano [6,7]. Estimation of the height of the lava tube cave under the vertical hole (H = 4fB / (ρg sin α)) was performed from the surface slope and the lava yield value of Arsia mons volcano [8]. Where the slope is steep,the thickness of the lava flow is not sufficient to form a large lava tube. The estimated tube height value in the vertical hole of the steep slope of the hillside of Arsia mons volcano (slope angle 1.0 ° to 3.5 °) has a large deviation from the vertical hole depth. Therefore, There is a high possibility of pit crater cave or fissure vent cave. On the other hand, in the vertical hole on the gentle slope of the foot (slope angle 0.12 ° to 0.54 °), the estimated lava tube cave height is almost the same as the estimated tube height, so it is highly possible that a lava tube cave exists [9].
[Conclusion]
Exploration of the internal structure of the vertical hole to clarify what the cavity under the vertical hole of Mars is firstly necessary for understanding the igneous activity. It is expected that the crater cave ,fissure vent cave or the lava tube cave will bring us clear understandings to the lava flow mechanism after the eruption.
References:
[1]T.Ogawa(1988):Dojin,Vol.7,No.3,p69-80
[2]O.Ohshima(1984):Kazan,Vol.29,No.2,p119-120
[3]O.Ohshima(1985):60A,Kazan,Vol.30,No.4,p.322-323
[4]T.Ogawa(1991):The rift caves in Japan,6th International Symposium on Vulcanospeleology 1991,p249-258
[5]T.Sameshima, T.Ogawa, and N.Kashima(1988): 5th International Symposium on Vulcanospeleology,Excursion Guide Book,p75-78
[6] G.Cushing et al(2007):Geophys.Res.Letters,Vol.34,L17201
[7]G.Cushing(2012): CANDIDATE CAVE ENTRANCES ON MARS,Journal of Cave and Karst Studies, April 2012
[8]T.Honda(2017):P117,Fall meeting of 2017 of the Volcanological Society of Japan
[9]T.Honda(2021):MIS12-P02,2021 meeting of JPGU
[10]J.Perala(2015): Pit Craters of Arsia Mons Volcano, Mars, and Their Relation to Regional Volcano-Tectonism, the Department of Earth Sciences, Uppsala University