Earthquake Shizuoka prefecture, Japan (01/08/2011) - 13 people injured (2 seriously)

Earthquake overview : Very strong shallow earthquake with epicenter in the middle of the Suruga Bay. The earthquake occurred just before midnight and was felt as far as Tokyo as a light shaking.

Intensity map courtesy JMA Japan - Yellow coloring : 5- intensity

ASTERSHOCK August 12 2011
M 5.0      2011/08/11 19:37     Depth 16.0  km     NEAR THE SOUTH COAST OF HONSHU, JAPAN
Friday, August 12, 2011 at 04:37:46 AM at epicenter
Shallow coastal earthquake approx. 20 km out of the Kikukawa coast.
Aftershock of the strong Shizuoka earthquake.
Max. JMA intensity : 2
This earthquake has only a very limited relation with the many aftershocks who are occurring in the eastern Honshu waters.
43 km (26 miles) SE of Hamamatsu, Honshu, Japan and 66 km (41 miles) SSW of Shizuoka, Honshu, Japan
Satellite map of the greater epicenter area

IMPORTANT and FINAL UPDATE 02/08 - 19:18 UTC :
- 13 people have been injured (2 seriously) by this earthquake.
- Damage to at least 27 houses .
- Leakage occurred in distributed water systems cutting off 1,500 households from drinking water for many hours.
- a lot goods have fallen from shelves in stores and supermarkets
- Some roads have been temporarily closed by rockfall.
- The Shinkansen bullet train and a number of JR trains were stopped for a limited time to inspect the rails for damage
- People living near the sea have auto-evacuated to higher ground in big numbers as a precaution against a possible tsunami. Although JMA never called a tsunami warning of advisory, people living close to the shores do not take any risk anymore.

UPDATE 02/08 - 08:27 UTC : We have still no Fire Department assessment for this earthquake. If there would have been serious damage or injured people a report was certainly published by now.

UPDATE 18:39 UTC  : Based on this new USGS data, we are anxiously awaiting the Fire Departments assessment reports for Shizuoka.

UPDATE 18:37 UTC  : USGS has updated his numbers. After recalculation they are reporting :
Magnitude : Mw 6.2
Depth : 10 km!
32 km (19 miles) S of Shizuoka, Honshu, Japan
60 km (37 miles) SW of Numazu, Honshu, Japan

UPDATE 16:01 UTC  : EMSC  has calculated its epicenter only 7 km from Oigawa (23,475 people). Yaizu, which has a population of 121,057 is at only 10 km following EMSC.

UPDATE 15:55 UTC  : Shizuoka is a very big city in Japan, It has a population of 724,026 during the lastest census.

UPDATE 15:55 UTC  : JMA reports a 5- (max. intensity for this earthquake) : Higashi-izu-cho Naramoto*, Yaizu-shi Hommachi*, Shizuoka Suruga-ku Magarikane

UPDATE 15:53 UTC  : The area is being rattled with numerous aftershocks

UPDATE 15:49 UTC  : USGS expects a strong shaking fro 740,000 people. 2,795,000 will have experienced a moderate shaking. The Felt report below is mentioning a rather long shaking of 30 seconds (always bad for eventual damage).

UPDATE : We will have to wait for the first FDMA reports to find out whether this earthquake was damaging or not. We expect some minor damage in the very populated bay area. All depends on the precise location of the epicenter.

UPDATE : epicenter following JMA is right in the middle of the bay. USGS is putting it more to the Western shoreline but also below the Bay.

UPDATE : USGS reports a magnitude of 5.9 at a depth of 21.9 km.

UPDATE : The area was severely damaged by a very strong shallow earthquake a few days after the March 11 earthquake.

UPDATE : The epicenter of this earthquake is close to Shizuoka and the Fuji volcano and mountain.

UPDATE : This earthquake will probably be harmless due the location of the epicenter. If this earthquake would have occurred below land, this might have been a damaging one.

Tokyo : around midnight local time Tokyo (MMI IV indicated - light shaking)
Gotemba :  (MMI V indicated - moderate shaking)
Tokyo : Just witnessed the earthquake which was mentioned with 6.1 before Suruga Bay in Tokyo.  Stay at the Westin Hotel in the 12 floor quite strong shaking could feel the whole hotel shaking with noices from the furniture. you felt the building swaying not nice, making somehow dizzy.. was quite long ca. 30 seconds....
FujiYoshida : MMI V (moderate shaking) indicated
Tokyo : Shaking was strong and long, even in Tokyo.  Shelves in my room almost toppled. The worry isn't from that though. This location is the expected area of the next big one. JMA press conference said they don't think it is the same mechanism that they are waiting on as a precursor, but people are nervous nonetheless. Strain on the Izu peninsula has been increasing since last night as well ( ). Hope this was isolated and we don't see any intensifying. ER remark : Today's science cannot predict what will happen in the near or even medium future. The knowledge is limited to the dangerous areas (mapped fault lines and historic earthquakes).  The 100% solution to your remark is a multi-billion answer.
Kozushima island : Was sleeping on the ground in a tent at a beachside campsite on Kozushima island. Shaking was more like a rolling, moderate to strong, and lasted a short while. The ground felt like a solid floating on a liquid. Like a raft on the sea subjected to a sudden series of moderate waves. There was a tannoy announcement and a patrol car drove by 3 times. I watched the sea, ready to cycle to higher ground if any changes observed. (MMI V moderate shaking indicated)

M 6.1      2011/08/01 15:01    Depth 20.0 km     SURUGA-WAN, JAPAN
23:58 JST 01 Aug 2011
Very strong shallow earthquake with epicenter in the middle of the Suruga Bay. The earthquake occurred just before midnight and was felt as far as Tokyo as a light shaking.
JMA reports a 5- intensity
Satellite map of the greater epicenter area

Most important Earthquake Data:
Magnitude : 6.1 (JMA) 5.9 (USGS) 6.2 (USGS)
UTC Time : Monday, August 01, 2011 at 14:58:11 UTC
Local time at epicenter :  Monday, August 01, 2011 at 11:58:11 PM at epicenter
Depth (Hypocenter) : 20 km (JMA) 21.6 (USGS) 10 km (USGS)
Geo-location(s) :
32 km (19 miles) S of Shizuoka, Honshu, Japan
60 km (37 miles) SW of Numazu, Honshu, Japan
64 km (39 miles) E of Hamamatsu, Honshu, Japan

Links to important maps
USGS Did You Feel It Map
Google satellite map of the area showing the kind of terrain the earthquake took place
USGS historic earthquakes map
USGS Seismic hazard map
USGS Impact on Population map
USGS Shaking map
GDACS earthquake report on twitter
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I have felt it Ik heb het gevoeld – Το έκανα αισθάνεται – Yo lo siento – 我的确感到了 – 私はそれを感じていました- Ich habe es gefühlt – Bunu hissediyorum yaptı – لم أشعر أنه


  1. JMA announced the quake on the 12th was of the same mechanism as the Tokai Quake. They also said they havent noticed any significant stress changes but that they are paying very close attention to the situation. Possibly not an aftershock then.