－Showing detailed positions of active faults based on latest expertise－
The Active Fault Map in Urban Area extracts active faults by aerial photo-interpretation, etc., compiling detailed locations of faults and directionality of slip, etc. in 1:25,000 scale topographic maps, and the seven newly released maps bring the total number of such maps to 163 nation-wide. (See below)
Access to the Maps
http://portal.cyberjapan.jp/site/mapuse4/?lkey1=fm&lopa1=1 (in Japanese)
The Active Fault Map in Urban Area is 1,000yen (including tax) per one sheet, and available at books stores that deal with maps nationwide.
Things gained from this survey
1. “TAZAWAKO”, “YOKOTE” and “YUZAWA” (in the Eastern Boundary Fault Zone of the Yokote Basin and its vicinity)
 The Shiraiwa Fault is a dip-slip* fault dipping on the West side and extending from Tazawakosotsuda in Senboku Shi to Otamachiota in Daisen Shi. In this survey, the section stretching northward from Tamagawa for approximately 2km was recognized as an active fault (Attachment 2-A). This survey also recognized the two faults dipping on the West side of this fault as active faults (Attachment 3-A, B).
 In the existing “New Edition: Active Faults in Japan” (Active Fault Research Group, 1991), the Higashi Chokai San Fault was shown in the section from Maemori 3-chome to Aikawahumoto in Yuzawa Shi, but in this survey it was recognized as an active fault extending on the North side from Iwasaki to Maemori 3-chome and on the South side from Aikawahumoto to the area of Takamatsu Gawa in Yuzawa Shi (Attachment 4-A, B).
2. “WATARI”, “SOUMA” and “MINAMISOUMA” (in the Futaba Fault Zone and its vicinity)
These maps show the Futaba Fault Zone (approximately 66km) and other active faults/presumed active faults. (Note: Fault lengths are within the range shown on these maps.)
 The Futaba Fault Zone extends in an almost South-North direction from Watari Cho in Miyagi Prefecture through Soma Shi to Minamisoma Shi in Fukushima Prefecture. This fault is dominantly of a left strike-slip nature with protuberances on the West side. Multiple traces of presumed active faults were recognized as faults in the Futaba Fault Zone. (Attachment 5-A)
 The section extending approximately 13km from around Oyachi to Kanaya in Minamisoma Shi was recognized in this survey as a confirmed active fault. In the section extending approximately 32km from Hatsunomachi in Soma Shi to Kanaya in Minamisoma Shi, which is a confirmed active fault in the Futaba Fault Zone, it is thought that there is fault movement mainly comprising a left strike-slip. (Attachment 6-A)
3. “TAKASAKI” (in the Northwestern Boundary Fault Zone of the Kanto Plain and its vicinity )
 The Fukaya Fault is a dip-slip* fault dipping on the Northeast side extending from Nakamuroda to Negoya in Takasaki Shi. Fukaya Fault in this map is largely split into three sections.
1) On the North side from Iwashiro to Shobuzawa in Takasaki Shi (2.5km), places with active flexure* can be seen in the dip-slip fault recognized to be dipping on the Southeast side in a North-Northeast/South-Southwest direction. This part has been newly recognized as an active fault in this survey. (Attachment 7-A)
2) Two to four almost parallel fault lines have been recognized from Yanaba to Kamitoyookamachi in Takasaki Shi (11.3km), diverging into two lines around Shimosatomi, and parts with flexural displacement can also be seen. (Attachment 7-B)
3) On the South side from Notsuke to Negoya in Takasaki Shi (6.3km), it has been recognized that there is a dip-slip fault dipping on the Northeast side. The Fukaya Fault to the South of Negoya is shown in the “Honjo/Fujioka” map. (Attachment 7-C)
 The Isobe Fault is a dip-slip fault that dips on the Northwest side extending from Shozen in Annaka Shi to Dainichi in Tomioka Shi. The fault is concealed from Hyuga to Shinchi in Annaka Shi. (Attachment 7-D)
(For items marked with a *, refer to “7. Explanation of terms” in Attachment 8)
- Attachment 1-1: The Eastern Boundary Fault Zone of the Yokote Basin and its vicinity; “TAZAWAKO”, “YOKOTE” and “YUZAWA” [PDF 212KB]
- Attachment 1-2: Futaba Fault Zone and its vicinity; “WATARI”, “SOUMA” and “MINAMISOUMA” [PDF 1472KB]
- Attachment 1-3: The Northwestern Boundary Fault Zone of the Kanto Plain and its vicinity; “TAKASAKI” [PDF 235KB]
Attachment 3: Part of “TAZAWAKO” and “YOKOTE” [PDF 327KB]
Attachment 4: Part of “YUZAWA” [PDF 301KB]
Attachment 5: Part of “WATARI”, “SOUMA” and “MINAMISOUMA” [PDF 209KB]
Attachment 6: Part of “MINAMISOUMA” [PDF 330KB]
Attachment 7: Part of “TAKASAKI” [PDF 449KB]
Attachment 8: About National Active Fault Zone Information Development (making of “Active Fault Map in Urban Area”) [PDF 154KB]