I check it on a daily basis and it's been rather quiet the past week or 2 or so. Actually I guess it's been rather quiet ever since the 1989 quake, but then a year or so ago I woke up in the morning from some rattling doors so I guess it all depends on your perspective.
So far the "worst" quake ever I experienced was in the Netherlands back around 1988. Magn. 5.2 or something. Which is interesting considering these happen like once every 6 million years or thereabouts
Actually I slept through it so I don't know if one can call it "experiencing".
We had a 6.2 last year in Costa Rica... We immediately regretted where we
had placed our racks and are almost finished a project to move them to a
concrete floor (rather than that compressed cardboard stuff). Lost a lot of
hard drives that day! We regularly have quakes between the 4-5 region here.
By regularly, i mean a minimum of 5 times a year in different parts of the
country.
Interesting, the epicenter was only a few km (about 30) from the capital
city and no communications were knocked out (except within a 6 km radius of
the epicenter which was affected more by mud slides knocking things over.
Here's what it looked like... http://www.youtube.com/watch?v=F8udXyyqUiw
When I lived in the Bay Area, I noticed that 4.x quakes only tended to
shake the room ever-so-slightly. You could only really tell if they
happened, if you happened to see liquid in a glass moving.
In California, 4s are a regular occurrence and we have 2-3s every day.
I rarely notice anything less than a 5, and, often do not notice up to a 5.5 in my area.
The worst quake I have personally experienced was the 1989 Loma Prietta quake
which was a 7.9 IIRC. It caused some significant damage to some substandard
(by modern measure, not when they were built) structures, most notably the bay
bridge and the cypress and embarcadero elevated freeways and a brick-and-morter
(literally) mall in Santa Cruz. Other than that, the damage from the 7.9 was minimal
outside of a relatively contained zone rather close to the epicenter.
I've been through more than one quake in the 5.2-5.5 range, so, perhaps they are
rare in the Netherlands (6 million years or so), but, in California they are much more
frequent, perhaps 5-7 years or so.
When I was living in San Jose/Sunnyvale and we had a 5.2 in 2001? (can't
remember the date, was a bit ago). The only effect I felt from it was as if
someone had taken the back of my chair and pushed it forward, that was about
it. Of course at the same time there was a large Earthquake in Turkey being
broadcast on the News, so thought it was just me, but when it came on the
news a few minutes later.... Since than I believe there have been several
5.0+ in that area, obviously none have been as significant as the one in
1988, but I think its only a matter of time till a large one occurs.
Something to keep in mind is that raw magnitude isn't the whole story. The
ground composition is *much* more important when it comes to destructiveness.
A 5.0 earthquake in the Netherlands might be extremely damaging because of
liquifaction. Also: California since we get quakes all the time, our rock is
more "shattered" which damps the seismic waves. Back east, on the other hand,
the bedrock is more solid which is why the New Madrid earthquakes traveled
so far (ringing bells in Boston, IIRC). Of course New Madrid were huge
earthquakes by any standard.
I've been through more than one quake in the 5.2-5.5 range, so, perhaps they are
rare in the Netherlands (6 million years or so), but, in California they are much more
frequent, perhaps 5-7 years or so.
Well, 6 million years was a "slight" exaggeration to get a point across. The Netherlands doesn't really have any quakes due to faultlines (there aren't any). But it does have the occasional quake due to coal/gas mining. Where the ground compacts or something like it.
Something to keep in mind is that raw magnitude isn't the whole story. The
ground composition is *much* more important when it comes to destructiveness.
A 5.0 earthquake in the Netherlands might be extremely damaging because of
liquifaction.
Yes the one I mentioned from the late 80s damaged buildings quite a bit around the epi centre in the SE. That would be damage such as falling roof tiles and cracks in walls. But then the Dutch do build a lot with brick and mortar. That's a big no no in places like California.
If there is interest in data centre provisioning or construction, disaster planning or inside/outside plant strategies intended to mitigate damage by earthquakes then the NZNOG list might well be a good English-language place to get some advice.
Earthquakes of magnitude 4 and up happen pretty regularly (several times per week is common).
The West Eifel volcanic field (SW of Bonn, Germany) is not far from NL and the last spectacular eruption there was about 9000 or so years ago (rather recently in geological terms). And there have been other significant earthquakes in the region in recorded history. The Lisbon quake in the 18th century was felt across much of Europe.
