Journal of Geography （地学雑誌）108 (4), 472-488，1999
Yukio HAYAKAWA *
*Department of Earth Science, Faculty of Education, Gunma University
I. Listed eruptions
This paper contains a catalog of volcanic eruptions of magnitude (M) 3 or greater during the past 2000 years in Japan (Table 1). The largest eruption of a volcano during this period and eruptions that caused loss of human life are also listed even if they did not reach M3. Many of the eruptions correspond with an identified deposit, but some are known only from human documents. Documents of ash-fall and (Pele's) hair-fall compiled by Omori (1918) are all listed, even those that may not describe volcanic eruptions. Fatal events including gas accidents are also covered whether or not they were caused by an eruption. For Fuji volcano, listed eruptions which occurred prior to 800 AD could not be dated with accuracy, but magnitude data is reliable.
As defining an eruption is arbitrary in some cases, I use the following criteria:
The total number of listings in the catalog is approximately 400.
II. Catalog format
The catalog consists of a single line of information for each eruption. It is arranged with Date (Date and Wareki) and Name (Volcano-Product), followed by Magnitude, Number of Fatalities, References (Reference, Shiryo, and Research), and Remarks. Some sections are abbreviated to save space.
Date indicates the start of the eruption. It consists of the integer representing the year, two decimal places representing the month, such as 01 for January, and third and forth decimal places representing the day. A round number, such as 1000, implies uncertainty. Julian Calendar is adopted for eruptions prior to 1582 AD, and Gregorian calendar after that. The dates of fatalities are all listed. If fatalities occurred not on the first day of the eruption, the magnitude section remains blank.
Wareki consists of era (written in Chinese characters), year, month, and day. They are expressed following the luna-solar calendar. Japan used a luna-solar calendar, Wareki, until 1872 AD. It is 30-60 days behind the solar (Julian or Gregorian) calendars. There is no formula to convert one to the other. The conversion is only possible by a table. The Wareki section remains blank for an eruption that does not appear in any human document. The era name may change partway through a year. Until the date of the change the old era name applies.
Volcano-Product provides the name of the volcano or source. It is followed by the name of the eruption or deposit in some cases. The Gazetteer section of "Volcanoes of the World" by Simkin and Siebert (1994) may be helpful to identify a volcano. It also provides latitude and longitude of volcanoes and their geographical locations. Contents pages of the catalog by JMA (1991, 1996) provide a correlation between Japanese and English names of volcanoes.
Magnitude is defined by M = log m - 7, where m is the mass of magma erupted in kg. Practically M is calculated by logarithmic summation of P (fallout M), I (ignimbrite M), and L (lava M), i.e. , 10M = 10P + 10I+10L.
Fatalities is the number of human deaths reported in documents.
Reference gives the name of ancient literature used for identification of the eruption and determination of the date. Nihon Funkashi by Omori (1918) is cited for most eruptions during the last period of Edo through Taisho eras. JMA Soran is a catalog published by Japan Meteorological Agency (JMA, 1991, 1996), which is frequently cited for recent eruptions especially for Izu islands. Kisyo Yoran is a periodical published by JMA. Shinbun means newspaper. Smithsonian indicates a book written by Simkin and Siebert (1994). If no literature exists, this section is labeled as Archaeology, Radiocarbon, Stratigraphy, or others. For the most recent eruptions, the section is marked just as news.
Shiryo is the Japanese name of Reference.
Research lists the most informative and original academic research papers. Special volumes of Bulletin of Volcanological Society of Japan are listed for some recent major eruptions. Only the first author is shown to save space. Initials of the second author are given if the paper was co-authored. '++' means a paper by three or more authors. Full authors' names, title, journal and other information are given in the References section at the end of this catalog, where papers written in Japanese are described in Japanese. A paper not personally examined is indicated with a slash mark, followed by the name of the paper that cites it.
Remarks briefly describe the character of the eruption, cause of death, reliability of the Reference and others. 'C' in '.34C' means radiocarbon age in thousand years.
III. Largest eruptions and total output
The largest eruption listed in the catalog is the Towada 915 (M5.7). Three successive eruptions in Hokkaido in the 17th century - i.e. Komagatake 1640, Toya (Usu)1663, and Shikotsu (Tarumai) 1667 - had the largest fallout eruptions, each reaching M5.4. The Towada 915 produced the largest (M5.6) pyroclastic flow that resulted in a widespread ignimbrite sheet. The Aira (Sakurajima) 1914 produced the largest (M5.6) lava flow. The deadliest eruption was the Unzen 1792, killing 15,000 people. Sakurajima in the Aira caldera has erupted the largest amount of magma, 9.8 x 1012 kg (M6.0) during the past 2000 years. The total magma erupted during the past 2000 years in Japan amounts to 48 x 1012 kg (M6.7).
This catalog is still in progress. The compilation is likely to be revised. Suggestions by e-mail to hayakawa@edu.gunma-u.ac.jp are welcome. An updated catalog will be posted on the Internet at http://www.edu.gunma-u.ac.jp/~hayakawa/catalog/index2.html
Acknowledgements
Reviews by Hidehiko Shimazaki, Kenji Satake, Brian Atwater, and Leonid Yoffe are acknowledged.