Dated to the first half of the 5th century, Konda Gobyōyama Kofun (誉田御廟山古墳) is the second largest tomb in Japan and is located in Habikino city (羽曳野市), Osaka prefecture.
According to the testimonies of researchers who conducted a non-invasive investigation of the tomb’s externals in 2008, it came to light on February 19 that a square dirt platform is located atop the zenpōbu (rectangular front of the keyhole tomb).
Designated as the tomb of Emperor Ōjin (応神天皇), it measures 420 meters long, making it the central tomb of the Furuichi Kofun Group (古市古墳群), located between Habikino city and Fujiidera city (藤井寺市). Not too far away is the well-known Mozu Kofun Group (百舌鳥古墳群) of Sakai city (堺市), the main tomb being Daisenryō Kofun (大仙陵古墳; attributed to Emperor Nintoku).
Raised platforms such as these are most often found atop the kōenbu (後円部; round rear of the tomb), near where the central personage was buried.
Notable exceptions to this structural pattern, besides the tomb in question, include Aotsuka Kofun (青塚古墳; picture below), which displays a small raised projection (danjō ikō 壇状遺構) about where the Konda Gobyōyama Kofun’s platform is located.
(picture source; unrelated to Konda Gobyouyama Kofun)
An additional location found for raised platforms, projections, and alters includes the sides of tombs. Minato Chausuyama Kofun has a projection along its north side, branching off from the zenpōbu (page 3 of this PDF [original source]). This raised projection (danjō ikō 壇状遺構) is connected to the kōenbu via a connecting bridge (rikukyō 陸橋).
The side projection is believed to be congruous to the shimajō ikō (島状遺構; island projection) found alongside certain large-scale Nara and Osaka tombs, including Suyama Kofun (巣山古墳; 220-meter zenpōkōenfun belonging to the Umami Kofun Group [馬見古墳群] in Nara prefecture, dated to late-4th/early-5th century; positioned as the tomb of a Katsuragi [葛城] family ancestor [Miyayama Kofun (宮山古墳) is another tomb associated with the early Katsuragi]), seen below.
(picture source)
These side projections are believed to have hosted various rites. Some posit that in the burial of the patriarch we can find ritual associated with the succession ceremony.
Those raised platforms found atop the kouenbu are believed to have been sacred alters or markers indicated spiritual boundaries.
Some interpret the placement of this platform on the far end of the keyhole tomb as suggesting an additional burial there — most likely a relative.
According to measurements created by the old Imperial Household Agency over 1oo years ago, the base (viewed from above) measured 40 meters and the top over 20 meters. The height of the dirt stage was measured at approximately 8 meters.
A similar square platform has been found atop Nishitonozuka Kofun (西殿塚古墳; also Nishitonotsuka Kofun), which is located in Tenri city, Nara prefecture, and measures 234 meters long. Posited by some as the final resting place of Iyo (壱与; also Toyo 台与), the successor to Himiko, it is dated to late 3rd to early 4th century. Another such platform was found atop Nara prefecture’s Sakurai Chausuyama Kofun (桜井茶臼山古墳), which yielded a cache of 81 bronze mirrors. The mound found atop Konda Gobyōyama Kofun, however, is the largest to date.
According to a newspaper article (the local paper delivered to my doorstep), it is believed that most kofun exhibiting multiple burials inter siblings. I am curious what evidence this statement is based on.
応神陵に巨大方形壇 前方部、血縁者を埋葬か
2011年2月19日 15:17日本で2番目に大きく、宮内庁が応神天皇陵に指定している前方後円墳、誉田御廟山(こんだごびょうやま)古墳(大阪府羽曳野市、5世紀前半)の前方部頂上に巨大な方形の土壇があることが19日、2008年に墳丘を立ち入り調査した研究者らの証言で分かった。
宮内庁が応神天皇陵に指定している誉田御廟山古墳=大阪府羽曳野市で共同通信社ヘリから通常は古墳の主を葬る後円部上にあり、聖域を示す結界や祭壇との説が有力。“埋葬施設の目印”とも言われ、同古墳では後円部の天皇だけでなく、前方部にも血縁者ら重要人物を埋葬した可能性が高いとみられる。
日本考古学協会などは24日、同庁の許可を得て内壕の土手を調査するが、墳丘本体への立ち入りは認められていない。
関係者によると、宮内庁陵墓管理委員会(考古学者ら8人)が08年秋、整備計画検討のため専門家として初めて墳丘内を立ち入り調査。
内容は非公表だが、委員の河上邦彦神戸山手大教授(考古学)によると、前方部の先端寄りに土を盛って築いた壇があった。保存状態は極めて良く、未盗掘の可能性もあるという。後円部には神社の施設が置かれた時期があり、土壇の有無などは確認できなかった。
http://www.nnn.co.jp/dainichi/knews/110219/20110219058.html
AR2011/02/20