(All articles are written in Japanese with English abstract and figure/table captions.)
Preface
Masato KOYAMA, Ryusuke IMURA, and Katsuhiko ISHIBASHI
Articles
False Eruption Record of the 1810 Kampu Eruption Created by Akita Clan Office at Edo (Tokyo)
Shintaro HAYASHI
Volcanic Eruptions and Hazrds of Asama Written in Historical Records
Yukio HAYAKAWA and Hideko NAKAJIMA
Shigeo ARAMAKI, Maya YASUI, Takehiro KOYAGUCHI, and Kanako KUSANO
Letters
On Height Distribution of Tsunami Caused by the 1640 Eruption of Hokkaido-Komagatake, Northern Japan
Yiichi NISHIMURA and Naomichi MIYAJI
Articles
Itoko KITAHARA
Reevaluation of the eruptive history of Fuji Volcano, Japan, mainly based on historical documents
Masato KOYAMA
Masato KOYAMA
Ryusuke IMURA
Ken'ichiro YAMASHINA
Letters
Dates of two major eruptions from Towada and Baitoushan in the 10th Century
Yukio HAYAKAWA and Masato KOYAMA
Photogravure
Paintings of the An-ei eruption of Sakurajima Volcano (A.D. 1779-1782) in the Kagoshima Prefectural Library
Ryusuke IMURA
Volume 43, No.6 (1998)
Articles
The eruption history of Iwate volcano in the Edo period, based on the historical documents
Jun'ichi ITOH
Volume 44, No.2 (1999)
Articles
Kenichiro YAMASHINA
Shintaro HAYASHI*
Kampu volcano is a small stratovolcano situated at the central part of Oga Peninsula, Akita Prefecture. In 1810, an earthquake as large as M6.5 occurred around this volcano. Yoshimasa Satake, the lord of the Akita clan, wrote two official reports to the Tokugawa shogunate. They included eruption records of Kampu volcano: "Yamayake" and "Yamayakekuzure". These words were usually used for the eruption during Edo period and mean that the mountain was firing. Several reliable documents, which was written at Oga Peninsula included no eruption record. In addition, there is no eruption record in the note of Yoshimasa Satake which is thought to have used for making the two official reports. It is concluded that the eruption records of 1810 Kampu is false and created by Yoshimasa Satake at Akita clan office at Edo (Tokyo). The false eruption might have been created to make the padded damage report of earthquake.
* Department of Earth Sciences, Faculty of Education and Human Studies, Akita University, 1-1 Tegata-Gakuen-Cho, Akita 010-8502, Japan
Yukio HAYAKAWA* and Hideko NAKAJIMA*
The 1108 eruption of Asama is the largest among numerous eruptions of the volcano during the Holocene. The magnitude is twice as large as that of the notorious 1783 eruption, which killed about 1,400 people. It is also the oldest written eruption of Asama. Chuyuki, which was written in Kyoto, 300 km SW of Asama, describes that the eruption started on September 29, 1108, by the Julian calendar, and that fields of rice and other crops were severely damaged. Many fatalities are strongly suspected by the distribution of the Oiwake ignimbrite, but no description is given for human loss in Chuyuki. A thin pumice layer intercalated between the 1108 scoria and the 1783 pumice can be correlated to a record of Pele's hair-fall in Kyoto in 1596. As many as 800 fatalities at the summit in 1598 described in Todaiki cannot be true. Tenmei Shinjo Hen'iki, which describes that a number of villages along the Jabori River were swept away by hot lahars in 1532, is not a contemporary document. It was written in the late 18th century. Fifteen fatalities at the summit in 1721 can be true. After the 1783 eruption, Asama was relatively quiet for 100 years. During the early and middle 20th century, Asama was very active with a peak of 398 times vulcanian explosions in 1941. About 30 lives were lost at the summit, in the 20th century, by 12 explosions among the total about 3,000 explosions.
*Faculty of Education, Gunma University, Aramaki-machi 4-2, Maebashi 371-8510, Japan.
Shigeo ARAMAKI*, Maya YASUI*, Takehiro KOYAGUCHI** and Kanako KUSANO*
The great eruption of Asama volcano in 1783 left a remarkable deposit of air-fall pyroclastic materials mainly on the east-southeastern foot of the volcano. We have collected descriptions of the pyroclastic fall events of this eruption from about 190 old documents which were recently compiled and published by Hagiwara (1985 - 1995). The data base created from these documents amounted to ca. 980 records from which thickness data of the deposits were compiled. In this study, we compared three types of thickness data: 1) data obtained in the field, 2) directly measured data as described in old documents, 3) recalculated data from the volume of the deposit as described in old documents. Thickness data obtained in the field, 160 years (Minakami, 1942) and 210 years (Yasui et al., 1997) after the eruption coincide with each other within the limits of error. Two tyeps of thickness data from old records show a well-established trend of sharp decrease with the distance from the vent, but the scatter of data points is so large that it is not possible to draw isopach lines over the entire deposit. Directly-measured thicknesses are about 1.7 times as large as the thicknesses calculated from the volume of the deposit , thus suggesting exaggerations in the former. Thicknesses calculated from the volume of the deposit appear about 2 times as much as the Minakami's (1942) data suggesting possible post-depositional compaction. However, due to the lack of reliable deta, both in old documents and in the measurements on historic deposits of other volcanoes, it was not possible to conclude that the post-depositional compaction plays an important role, suggesting a strong need for further research.
*Department of Earth Sciences, Nihon University, 3-25, Sakura- josui, Setagaya-ku, Tokyo 156-8550 Japan **Earthquake Research Institute, University of Tokyo, 1-1-1, Yayoi, Bunkyou-ku, Tokyo 113-0032 Japan
Itoko KITAHARA*
The purpose of this paper is to give an analysis of the spreading of disaster information in the case of 1888 A.D. eruption of Bandai Volcano. A socio- historical approach focusing on newspaper articles, magazines, and other printed matters is adopted to analyze the disaster process.
The 1888 eruption of Bandai Volcano was the first experience of a great natural disaster for the Meiji government, which was just under the process of developing the modern nation. The social structure of information in the transit time and its relation to the modernizaition process in the educational field of physical geograpy, will be discussed.
The newspaper articles about the Bandai Eruption can be characterized into the following three stages in chronological order;
1) Reports on the outbreak of the disaster, the initial damage, and the dispatch of the government officials for investigations of the volcano.
2) Further reports on the damage and the donation campaign raised by the newspapers.
3) More on donation campaigns for much more donations among the general public.
These three stages clearly show that the social background had changed from the pre-modern society. Having gone through the contemporary understandings about volcanic eruptions and earthquakes with the age of Bandai eruption, and taking the modernization of educational system into consideration, the following reasons for the changes can be pointed out;
(a) After the Meiji Restoration accompanied with the so-called gScientific Revolutionh of Japan, the young generation raised under the modern educational sysytem had more scientific attitude to natural phenomena than those of previous generations.
(b) The combined effect of the traditional system of charity activities and the new type of donation which was raised by newspapers and other media, such as disaster photographs or charity performances were quite effective in helping the people struck with the disaster under the conditions of the insufficient governmental relief.
*4-4-1-5-201 Nara, Aoba-ku, Yokohama 227-0036, Japan
Masato Koyama*
All available historical documents, which record abnormal phenomena relating (or possibly relating) to the activity of Fuji Volcano, Japan, were re- examined and classified according to the reliability of each document. Comparisons of the reliable descriptions with geologic evidence were executed and several new correlations between historical records and eruptive deposits are proposed. Volcanic activity of Fuji Volcano was in high-level from the 9th to 11th century; in this period at least 7 reliable and 5 possible eruptions occurred. Although only 2 reliable and 1 possible eruption records exist from the 12th to the early 17th century, this low-level activity may be apparent because of lack of enough historical records. After the middle 17th century, enough historical records suggest that the activity is generaly low except for the 1707 eruption, which is one of the most voluminous and explosive eruptions in the history of Fuji Volcano. At least thirteen large earthquakes (M8 and possible M8 class) have occurred near Fuji Volcano (in east Nankai and Sagami Troughs) since the 9th century. Eleven of these 13 earthquakes were accompanied with volcanic events (eruption, rumbling, or change in geothermal activity) of Fuji Volcano before and/or after each earthquake (in +-25 years).
*Faculty of Education, Shizuoka University, 836 Oya, Shizuoka 422-8529, Japan
Masato Koyama*
Reevaluation of places, type, magnitude, and influences of the 800-802 A.D. eruption (Enryaku eruption) of Fuji Volcano, Japan, was made through tephrochronology and analyses of historical records. The Nishi Kofuji fissure on the northeastern slope is newly recognized as a crater of the 802 A.D. flank eruption. The Nishi Kofuji fissure ejected fallout scoria toward ENE and lava flows, which can be correlated with Takamarubi and Hinokimarubi II Lavas on the northeastern foot. The Tenjinyama-Igatonoyama fissure on the northwestern slope probably erupted during the Enryaku eruption and ejected fallout scoria and lava flows.
A series of historical documents and paintings (Miyashita documents), which are unauthorized, personal records and are regarded to be unreliable by many historians, includes many detailed descriptions of paleogeography around Fuji Volcano and of the Enryaku eruption. Although some of the descriptions were exaggerated and conflict with geological observations, some of them are concordant with geologic data.
The Enryaku eruption probably gave serious damages to ancient traffic routes particularly on the northwestern-northeastern foot of Fuji Volcano. The Gotenba area, which is located on the eastern foot, was also damaged by thin ash-fall and probably by lahars. This caused a temporal, southward relocation of the offical traffic route, which had passed through the Gotenba area.
*Faculty of Education, Shizuoka University, 836 Oya, Shizuoka 422-8529, Japan
Ryusuke Imura*
The eruptive sequence of An-ei eruption of Sakurajima volcano (1779- 1782) is revealed by historical records. From the evening of November 7, 1779 (the 29th day of the 9th month in the 8th year of An-ei), Kagoshima and its environs were shaken frequently. At 11 a.m. of the next day, the water in the wells in the island boiled up, spouting at several points and the color of sea became purple. On the noon of the same day, minor white plumes rose up from the Minamidake summit crater. At about 2 p.m., plinian eruption occurred at the southern upper slope of Minamidake, and several tens of minutes later, at the northeastern flank of Kitadake. The height of eruption column reached about 12000 meters. It is estimated that a pyroclastic flow was generated at 5 p.m. The plinian eruption climaxed from the evening of November, 8 to the morning of next day, and later was followed by emission of lava flows. The activity of the southern craters ceased within a few days, but lava emission from northeastern craters lasted for a long period. On November 11, the lava flow from northeastern craters entered into the sea. Since then, submarine explosions occurred repeatedly off the northeastern coast, and it continued to January 18, 1782. Nine small islands produced by this submarine volcanic activity during a year. Submarine explosions caused small tsunamis on August 6 and 15, September 9, October 31, November 9, 1780 and April 11, 1781.
*Korimoto 1-21-35, Kagoshima, 890-0065 Japan Department of Earth and Environmental sciences, Faculty of Science, Kagoshima University
Ken'ichiro YAMASHINA*
Various suggestive documents and associated sketches are collected for understanding the pre-eruptive and the earliest stages of the 1914 great eruption of Sakurajima volcano, southwestern Japan, in Taisho era. Based on these records, the premonitory process to the eruption was reviewed especially with respect to the occurrence of many earthquakes which resulted in repeated rock falls with dust clouds, unusual upwelling of water and hot spring, and emission of volcanic smoke in the morning of January 12. Although there are many descriptions on the beginning of the remarkable eruption, they are sometimes inconsistent with each other. In the present paper, it is proposed that the valcano started to erupt around 09:58 on January 12 (Japanese Standard Time)at 200 m in height in the western slope of the mountain. In a several minutes, a line of craterlets was formed between 200-500 m in height in the WNW-ESE direction. The development of a subsurface fissure in this direction resulted in another outbreak in the southeastern slope probably around 10:05. For the better understanding of this important eruptive event, discoveries of additional references are still desiered.
*Earthquake Research Institute, University of Tokyo Yayoi 1-1-1, Bunkyoku, Tokyo 113-0032, Japan
The eruption history of Iwate volcano in the Edo period, based on the historical documents
Jun'ichi ITOH*
It has been regarded that the eruption activity had been generated
at the Iwate volcano in AD
1683, 1686-89, 1719, 1730 and 1732. In this study, the eruption
history of Iwate volcano in
the Edo period is reexamined by judging the credibility of historical
records of eruption. The
following conclusions were obtained from my investigation. a)
The mistake is found in the
description of the age in the historical document which has been
regarded as the evidence of the
1683 eruption. b) According to a letter of the previous lord of
Morioka clan and the reports of
government authorities, a violent eruption began with eruptive-column
forming above central
crater of the stratovolcano on March 26 AD1686, and became quiet
in the early morning of
27th. The pyroclastic deposit discharged by this eruption is the
Kariya scoria with the
distribution axis from the central crater in northeast and the
southeast foot. The volcanic
hazard by this event was caused due to the lahar which occurred
because of the melt of the
snow of the mountain. Human damage did not occur though several
houses were swept away
by lahars. c) The credibility of the historical documents assumed
for the 1686 eruption which
continued even in AD1687 and AD1689 is weak. In fact, the eruption
started in AD1686 was
ended within the year. d) The credibility of historical documents
which describe the 1719 and
1730 eruption is also extremely weak. f) The 1732 eruption was
recorded in the administrative
report of Morioka clan. This historical documents describe the
effusion of lava flow from the
northeastern foot of the Iwate volcano. It is assumed that this
report corresponds to
Yakehashiri lava flow. The lava effusing started at midnight of
January 21 and continued for
7-10 days. The inhabitant who resided in the the foot of the mountain
was evacuated from the
village due to frequent volcanic earthquake. The human and material
damage did not occur in
this eruption.
*Geological Survey of Japan, 1-1-3 Higashi, Tsukuba, Ibaraki
305-8567, Japan.
Volcanic Cloud Height of the 1914 Eruption at Sakurajima Volcano - Discussions on Documentary Records and Photographs
Ken'ichiro YAMASHINA *
Associated with the 1914 great eruption at Sakurajima volcano,
southwestern Japan, the maximum
height of volcanic cloud is discussed based on collected documents,
sketches and photographs in those
days. A series of photographs up to around 10:40 on January 12
(in Japanese Standard Time)
represents that the volcanic cloud height attained to 7,000 to
8,000 m above sea level. After then, it
proved that several documents reported the height to be 9,500
- 15,000 m, or even more than 18,000
m a.s.l, although it is difficult to obtain reliable evidences.
Considering these reports and other
observations from a distance, the height of 15,000 m is tentatively
proposed here as a possible
maximum value. According to an empirical relation, an eruption
rate of small pyroclastic materials is
suggested as, roughly speaking, 5,000 tons per second or 20 millions
of tons per hour, if the volcanic
cloud was 15,000 m in height.
* Earthquake Research Institute, University of Tokyo
Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-0032, Japan