Update 17:20 UTC : The number of injured has increased to 20

Update 16:43 UTC : In the 16:23 update we did talk about a Thrust type earthqauke. This was confirmed by the following report : In Joetsu,  the road has been lifted about 50cm (Kiyosato District Kaminakajo district)

Update 16: 39 UTC : The latest reports are mentioning 11 injured

Update 16:23 UTC : The damage looks rather limited if we take the strong Magnitude into consideration. One of the main reasons is the earthquake type. Based on the USGS beach-ball below we are looking at a thrust focal mechanism (2 plates pushing towards each other. The resulting movements are far less dangerous than transform earthquakes (the type which hit China today). An additional reason to have weaken the shaking is the location it occurred, the rocky Japanese Alps. This kind of underground does not transmit the earthquake waves like it would be the case in for example a sediment valley.

Update 16:12 UTC : As we are after midnight in Japan, rescue operations take more time. In some parts of the epicenter area the power is down. There are also reports of broken water pipes, a ruptured fuel tank leaking 1000 liter of oil. Collapsed walls etc. It will take at least 5 to 6 hours (early morning) before we will get a good picture of the damage.

Update 16:01 UTC : So far at least 4  people injured

Update 14:38 UTC : As could be expected, multiple landslides have been notices (these are the Japanese Alps). One of these landslides is blocking the Shirasawa tunnel who links Nagano with Hakuba

Important Update 14:27 UTC : Several buildings collapsed and people possibly buried in Nagano Prefecture. (Source NHK Japan) Update : 4 houses should have been collapsed. No further news at the moment.

Update 14:17 UTC : The Nagano Fire Department is reporting several injuries and a building collapse after 6.8 quake this evening.

Update 14:13 UTC : Kyodo News Reports that Hakuba Village (famous for the 98 olympics) has seen a building collapse.

Update 14:11 UTC : Image of a convenience store in Nagano

Update 14:06 UTC : The city of Nagano has not sustained damage so far (this would be seen almost immediately). Power is still on in Nagano based on the webcam we are looking at. So far we have reports of 2 people who have been injured in Hakuba (ambulance under way).

Update 14:01 UTC : Below the theoretical shaking map of USGS based on a M6.2 Magnitude (JMA Japan reports M6.8)

Update 13:51 UTC : The Nagano prefecture authority has reported that the Kashiwazaki-Kariwa nuclear power plant sustained NO damage but has been shut down as a precautionary measure.

Update 13:47 UTC : Shaking of the Nagano earthquake (ni mention of distance from the epicenter)

Update 13:43 UTC : until now only reports from items falling from shelves. No structural damage so far (too soon to be final of course) (thx to @RobertSpeta living in Japan)

Update 13:37 UTC : Prof. Max Wyss who specializes in theoretical calculations of injured and fatalities based on many parameters expect for this earthquake 0 to 10 fatalities and 0 to 100 injured. He has used the GFZ data (M6.2 at 10 km for his calculations).

Update 13:31 UTC : We expect the whole Nagano prefecture at risk for damage and injuries.

Update 13:30 UTC : EMSC and USGS are reporting a M6.2 Magnitude bur JMA Japan maintains his M6.8 Magnitude at 10 km.

Update 13:24 UTC : Shaking values who may lead to damage. Landslides are almost a certainty! Of course NO tsunami risk because the earthquake happened below mainland Honshu

6-    Nagano-shi Togakushi*, Nagano- shi Kinasa*, Otari-mura Nakaotari*, Ogawa-mura Takafu*
5+    Nagano-shi Hakoshimizu, Nagano-shi Toyonomachi-Toyono*, Nagano-shi Nakajo*, Hakuba-mura Hokujo* and Shinano-machi Kashiwabara-higashiura*
5-    Nagano-shi Shinshushimmachi-shimmachi*, Nagano-shi Ooka*, Nakano-shi Toyotsu*, Omachi-shi Yasaka*

Update 13:22 UTC  : JMA Japan has a theoretical shaking of -6 We at Earthquake-report.com consider 5+ already as probably damaging. The earthquake happened at a shallow depth below Eastern Honshu

16km (10mi) NNE of Omachi, Japan
24km (15mi) W of Nagano-shi, Japan
33km (21mi) N of Hotaka, Japan
36km (22mi) W of Suzaka, Japan
191km (119mi) NW of Tokyo, Japan