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There are no activity reports for Iwatesan.
Summary of eruption dates and Volcanic Explosivity Indices (VEI).
|Start Date||Stop Date||Eruption Certainty||VEI||Evidence||Activity Area or Unit|
|[ 1934 Jul ]||[ 1935 ]||Uncertain|
|1919 Jul 15 (?)||1919 Jul 15 (?)||Confirmed||1||Historical Observations||W side of Onigajo caldera (O-jigokudani)|
|[ 1823 ]||[ Unknown ]||Discredited|
|1732 Jan 22||1732 Oct (?)||Confirmed||2||Historical Observations||NE flank of Yakushi-dake|
|[ 1719 Feb (?) ]||[ Unknown ]||Discredited|
|[ 1689 Jun 22 ]||[ Unknown ]||Uncertain||2|
|[ 1687 Apr 14 ]||[ 1687 Jul ]||Uncertain||2|
|1686 Mar 26||1686 Mar 27||Confirmed||3||Historical Observations|
|1450 ± 100 years||Unknown||Confirmed||Radiocarbon (uncorrected)||Nishi-Iwate and Higashi-Iwate|
|1300 ± 50 years||Unknown||Confirmed||3||Tephrochronology||Higashi-Iwate (Myoko-dake)|
|0150 (?)||Unknown||Confirmed||Radiocarbon (uncorrected)||Higashi-Iwate|
|0350 BCE (?)||Unknown||Confirmed||Radiocarbon (uncorrected)||Higashi-Iwate|
|0450 BCE (?)||Unknown||Confirmed||Radiocarbon (corrected)||Nishi-Iwate (O-jigokudani area)|
|1150 BCE (?)||Unknown||Confirmed||Radiocarbon (uncorrected)||Nishi-Iwate|
|1250 BCE (?)||Unknown||Confirmed||3||Radiocarbon (corrected)||Higashi-Iwate|
|1500 BCE ± 300 years||Unknown||Confirmed||Tephrochronology||Higashi-Iwate|
|1650 BCE (?)||Unknown||Confirmed||Radiocarbon (corrected)||Nishi-Iwate (O-jigokudani area)|
|2000 BCE (?)||Unknown||Confirmed||Radiocarbon (corrected)||Nishi-yama|
|2050 BCE ± 200 years||Unknown||Confirmed||Radiocarbon (corrected)||Higashi-Iwate, W5 tephra|
|2700 BCE ± 200 years||Unknown||Confirmed||Tephrochronology||Higashi-Iwate, W6a-d tephras|
|2950 BCE ± 50 years||Unknown||Confirmed||Radiocarbon (corrected)||Nishi-Iwate, PHD5 tephra|
|3050 BCE (?)||Unknown||Confirmed||Radiocarbon (uncorrected)||Higashi-Iwate|
|3250 BCE ± 500 years||Unknown||Confirmed||0||Tephrochronology|
|3750 BCE ± 100 years||Unknown||Confirmed||Tephrochronology||Higashi-Iwate|
|4350 BCE ± 500 years||Unknown||Confirmed||Tephrochronology||Higashi-Iwate|
|4450 BCE ± 500 years||Unknown||Confirmed||0||Tephrochronology||Higashi-Iwate|
|4850 BCE ± 50 years||Unknown||Confirmed||Radiocarbon (corrected)||Nishi-Iwate, PHD6 tephra|
|4900 BCE ± 100 years||Unknown||Confirmed||Radiocarbon (corrected)||Higashi-Iwate|
|5650 BCE ± 50 years||Unknown||Confirmed||Radiocarbon (corrected)||Nishi-Iwate, PHD7 tephra|
|6300 BCE ± 100 years||Unknown||Confirmed||Radiocarbon (corrected)||Nishi-Iwate, PHD8 tephra|
|6450 BCE ± 1000 years||Unknown||Confirmed||Tephrochronology|
The following references are the sources used for data regarding this volcano. References are linked directly to our volcano data file. Discussion of another volcano or eruption (sometimes far from the one that is the subject of the manuscript) may produce a citation that is not at all apparent from the title. Additional discussion of data sources can be found under Volcano Data Criteria.
IAVCEI, 1973-80. Post-Miocene Volcanoes of the World. IAVCEI Data Sheets, Rome: Internatl Assoc Volc Chemistry Earth's Interior..
Itoh J, 1998. The eruption history of Iwate volcano in the Edo period, based on the historical documents. Bull Volc Soc Japan (Kazan), 43: 467-481 (in Japanese with English abs).
Japan Meteorological Agency, 2013. National Catalogue of the Active Volcanoes in Japan (fourth edition, English version). Japan Meteorological Agency.
Japan Meteorological Agency, 1996. National Catalogue of the Active Volcanoes in Japan (second edition). Tokyo: Japan Meteorological Agency, 502 p (in Japanese).
Kudo T, Hoshizumi H, 2006-. Catalog of eruptive events within the last 10,000 years in Japan, database of Japanese active volcanoes. Geol Surv Japan, AIST, http://riodb02.ibase.aist.go.jp/db099/eruption/index.html.
Kuno H, 1962. Japan, Taiwan and Marianas. Catalog of Active Volcanoes of the World and Solfatara Fields, Rome: IAVCEI, 11: 1-332.
Nakano S, Yamamoto T, Iwaya T, Itoh J, Takada A, 2001-. Quaternary Volcanoes of Japan. Geol Surv Japan, AIST, http://www.aist.go.jp/RIODB/strata/VOL_JP/.
Tanaka S, Hamaguchi H, Ueki S, Sato M, Nakamichi H, 2002. Migration of seismic activity during the 1998 volcanic unrest at Iwate volcano, northeastern Japan, with reference to P and S wave velocity anomaly and crustal deformation. J Volc Geotherm Res, 113: 399-414.
Viewed from the east, Iwatesan volcano has a symmetrical profile that invites comparison with Fuji, but on the west an older cone is visible containing an oval-shaped, 1.8 x 3 km caldera. After the growth of Nishi-Iwate volcano beginning about 700,000 years ago, activity migrated eastward to form Higashi-Iwate volcano. Iwate has collapsed seven times during the past 230,000 years, most recently between 739 and 1615 AD. The dominantly basaltic summit cone of Higashi-Iwate volcano, Yakushidake, is truncated by a 500-m-wide crater. It rises well above and buries the eastern rim of the caldera, which is breached by a narrow gorge on the NW. A central cone containing a 500-m-wide crater partially filled by a lake is located in the center of the oval-shaped caldera. A young lava flow from Yakushidake descended into the caldera, and a fresh-looking lava flow from the 1732 eruption traveled down the NE flank.