Ata Caldera

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Coordinates: 31°24′N 130°38′E / 31.40°N 130.64°E / 31.40; 130.64
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Ata Caldera
Postulated limits of the Ata Caldera have varied over time in the scientific literature. Some recent definitions and evidence would include most of both of the indicated areas in this map.[1][2]
Highest point
PeakMount Kaimon, 31°10′48″N 130°31′42″E / 31.18000°N 130.52833°E / 31.18000; 130.52833
Elevation924 m (3,031 ft)
Coordinates31°24′N 130°38′E / 31.40°N 130.64°E / 31.40; 130.64[3]
Dimensions
Length25 km (16 mi) NS
Width15 km (9.3 mi) EW
Naming
Native name阿多カルデラ (Japanese)
Geography
Ata Caldera is located in Japan
Ata Caldera
Ata Caldera
CountryJapan
StateKagoshima Prefecture
RegionIbusuki, Kagoshima, Kimotsuki District, Tarumizu
Geology
Age of rockPleistocene (240,000 years ago) onwards
Mountain typeCaldera
Somma volcano
Last eruption885 CE[3]

Ata Caldera (阿多カルデラ, Ata karudera), containing the Ata North Caldera, Mount Kaimon and Ikeda Caldera amongst other volcanoes, is a massive, ill defined, mostly submerged volcanic caldera associated with the southern portions of Kagoshima Bay.

Geology

The earliest tephra assigned to the volcano, is the widespread on regional sea bed cores, Ata–Torihama tephra (Ata-Th) at 240,000 years before the present.[4]

The caldera contributed to an eruption which has been dated to about 100,000 years before present (range by various techniques mostly fall 100,000 to 109,000) that generated the Ata tephra in southern Japan.

VEI of 7.5 and generated over 300 km3 (72 cu mi) of tephra.[6] This is overlaid in some places in Japan by the more recent Mitake No. 1 (On-Pm1) tephra from an eruption in the Mount Ontake area and K-Tz tephra from the Kikai Caldera.[5]
There have been many more lesser eruptions.

Structure

Some of the recent literature separates the caldera into a northern almost completely submerged caldera that generated the Ata tephra and Ata ignimbrite, and a southern caldera which includes the recently active

Ibusuki Volcanic Field. [1] This southern caldera first had the Ata name but is not believed now to be associated with the vents of the major eruption of 100,000 years ago.[7] High resolution Bouguer gravity imaging of Kyushu is consistent with the larger caldera being the Ata North Caldera but suggests it may be centered near the island of Chiringashima, and that the Ata South Caldera is the smaller in size, overlaps it being centred near Yamagawafukumoto district.[2]

The National Catalogue of the Active Volcanoes of Japan (JMA, 2013) included features of the

Ibusuki Volcanic Field as part of the Ata post-caldera system.[3] By this definition the single caldera may be a rounded triangle about 30km in length and up to 25km in width,[1]
although the usual quoted size is smaller.

Relationships

Immediately adjacent to the north of the caldera is the

Amur Plate and the Pacific Plate
is subducting under both.

References

  1. ^ a b c d "IAVCEI 2013 Scientific Assembly A Guide for Mid-Conference Field Trip". Retrieved 2022-09-19.
  2. ^
    ISBN 3-540-24055-1
    .
  3. ^ a b c "Ata |Global Volcanism Program | Smithsonian Institution". volcano.si.edu. Retrieved 2022-09-19.
  4. S2CID 45727649
    .
  5. ^
    S2CID 146526393
    .
  6. ISSN 0277-3791
    .
  7. ^ a b Matumoto, Tadaiti (1965-08-28). "Calderas of Kyusyu" (PDF). Transactions of the Luna Geological Field Conference. Retrieved 2022-09-19.
  8. S2CID 218652170
    .
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