Here's the map from the Japan Meteorological Agency (JMA) for the Mag. 7.3, also showing the shindo (shaking) by region:
[The map and a full list of shindo rates by region can be found on the JMA site
. I didn't copy the list as it's very long, so if you have interest in a
specific region of Japan, just refer to the linked page.]
The shaking in near-coastal regions nearer to the quake ranged from shindo 5 upper down to around shindo 4. Shindo 5 is pretty strong and certainly
for the Fukushima Dai-ichi nuclear power plant's fragile structures, this is something they'd rather not see.
It's fortunate that the quake wasn't more powerful or closer to shore, but even so it does underline the concerns of many people in Japan and
elsewhere about the other potential nuclear disasters they could experience in the event of another mega-thrust quake along their extensive subduction
Regarding wherther this quake is an aftershock of last year's event, an independent event, or even a foreshock: as TA said, it might be a foreshock
but there is no way we can know unless a bigger quake hits in the same region and within the same or a connected fault system. And going by the
USGS summary for today's quake
, while it might not be a direct
aftershock of the March 2011 event, it could well be that the prior, huge event destabilized the fault where this quake occurred. As they say, this
was a reverse faulting event near a plate boundary, but the region is very complex and there are many factors (and potential stressors) involved.
We are now in a wait-and-see mode. We can definitely expect a fair number of aftershocks to this event as they are typicla for the region and also for
a reasonably shallow quake. (Note that JMA has it shallower than USGS.) So, no-one should be surprised if we see several aftershocks in the mag 5
range and even another one or two up into the low six range.
edit on 7/12/12 by JustMike because: Added link back to JMA for the map. Added comments re aftershocks etc.