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Migs, there was already slight damage here from a German quake 4.something.  We all know it's not as seismically active here, but we also know that that just decreases the frequency.  the point is that buildings in Japan or on the west coast are built for the frequency, but those standards don't exist in northern Europe.

"Life shrinks or expands in proportion to one's courage." - Ana´s Nin
by Crazy Horse on Thu Feb 28th, 2008 at 04:55:50 PM EST
[ Parent ]
My point is that buildings are built to withstand the likely hazards. So you can expect the same amount of damage from a "typical" earthquake in Germany as in California. It's just that the "typical" earthquake has a different intensity so things are more earthquake-proof in California than Germany.

It's a case of bringing risk down to roughly the same tolerable level, in different circumstances.

We have met the enemy, and he is us — Pogo

by Migeru (migeru at eurotrib dot com) on Thu Feb 28th, 2008 at 04:59:35 PM EST
[ Parent ]

I'd be very surprised to learn that anything in Sicily has been built to survive a "typical" earthquake (7.5 in 1908).
by gk (gk (gk quattro due due sette @gmail.com)) on Fri Feb 29th, 2008 at 02:16:35 AM EST
[ Parent ]
Hence the scare quotes around "typical".

We have met the enemy, and he is us — Pogo
by Migeru (migeru at eurotrib dot com) on Fri Feb 29th, 2008 at 03:44:00 AM EST
[ Parent ]
even when seismology is not my strongest suit, but I have the same suspicions of gk. Modern Europe has lucked out so far.

Previously, we've touched upon about earthquakes in Switzerland. Historically we also know about Italy, both in the  south but also north (Friuli, Umbria) and even Portugal (which I don't really understand at first glance). The only European country which has to deal with major earthquakes at a fairly regular basis is Greece.

Anything above 7.0 Richter scale with an epicentre nearby a major city may well give abhorrent chaos in countries where modern architecture has not been previously tested by a big quake. I'd suspect some hazard evaluation should be available at the seismological services in each country, but I already have a PhD to finish...

by Nomad on Fri Feb 29th, 2008 at 02:53:25 AM EST
[ Parent ]
The Lisbon Earthquake had its epicentre quite far from Lisbon.

How strong have the earthquakes been in Switzerland? Magnitude 4?

There are earthquakes in the Alps, but the major plate boundary (responsible for the Lisbon earthquake) is in the Southern Mediterranean (which explains Turkey, Greece, Southern Italy and Southern Spain).

Though there is this:

Plate tectonics - Wikipedia, the free encyclopedia

Not all plate boundaries are easily defined. Some are broad belts whose movements are unclear to scientists. One example would be the Mediterranean-Alpine boundary, which involves two major plates and several micro plates.
I still think if Germany were at all likely to have a magnitude 7 earthquake, it would have a fair number of magnitude 6 earthquakes, and construction would be earthquake-proof enough to sustain no damage from a magnitude 5 earthquake.

We have met the enemy, and he is us — Pogo
by Migeru (migeru at eurotrib dot com) on Fri Feb 29th, 2008 at 03:43:02 AM EST
[ Parent ]
Whoops, missed a pic:


We have met the enemy, and he is us — Pogo
by Migeru (migeru at eurotrib dot com) on Fri Feb 29th, 2008 at 03:45:36 AM EST
[ Parent ]
To find out what the recorded seismicity in the Basel area, I'd recommend you to here. You need the latitude and longitude of the area in question. The university server is slowing down - otherwise I could've done it right away.

The Basel earthquake has been estimated with a intensity of IX, which can probably be correlated to a Richter scale (or the more accurate Seismic Moment). I found a hazard analysis on Basel here wherein they write:

Earthquake Scenarios for the City of Basel

The calculated scenarios are an intensity VII - VIII earthquake and one of intensity IX. These represent the expected value with return period of 475 years generally used in building codes, and the intensity of the earthquake in 1356.

Meaning, the building codes do no provide for earthquakes the magnitude of the 14th century Basel quake, and the estimated damage is considerable (Fig 1). How likely is it that we'll have another one? Don't know, but the very fact that one happened should bear caution - it's a known unknown. If stress can build up in that region to such levels, it can happen again.

The simplification of the plates in the picture works as a first approximation concept - there is no nicely defined 8 pixel line, especially when it concerns converging plates which is a very messy process. The idea one would get from the picture above when focussed on the African-EuroAsian plate margins is completely wrong. One would have to zoom in on the Mediterranean, start here.

Yes, most of the tectonic action is concentrated at a particular zone and you're correct that the majority of the major earthquakes will be centred around the Mediterranean countries. The uncertainty is: what's the extent of major seismic event towards the north? For now, we know at least Basel, and the north of Italy, can be affected. Although, for Basel, it's not clear to me if it's because of plate convergence to the south or by normal faulting as a response to crustal loading.

by Nomad on Fri Feb 29th, 2008 at 06:17:37 AM EST
[ Parent ]
Let's see...

To address the original comment, Germany doesn't appear on Wikipedia's List of deadly earthquakes since 1900.

Portugal had a magnitude 7.8 in 1969 which killed 13 people (both the earliest and strongest on the list for Portugal, which suggests a gap in the data).

Spain has one in magnitude 5.3 in 1997 which killed one person.

The strongest on the list for France was a magnitude 4.2 which killed one person in 2001. The weakest and earliest is a 3.5 in 1983, also killing one.

Switzerland is not on the list, and neither is Austria.

Italy has 31 earthquakes on the list. The earliest is a magnitude 6.8 in 1905, killing about 1200 people. The weakest is a 4.2 in 1987, killing 2. The strongest is a 7.2 in 1908, killing 80 thousand.

Greece has 39. The earliest and strongest is a magnitude 8.2 in 1903, killing 2. The weakest is a 4.6 in 1978, killing 1. The deadliest is a 7.2 in 1953, killing 600.

Japan has 74 earthquakes on the list. The earliest is a 7.0 in 1900. The strongest is an 8.4 in 1933, killing 3,000. The deadliest is the 1923 Kanto Earthquake, magnitude 7.9 killing 140 thousand.

The US (excluding "minor outlying islands") has 29. The earliest, strongest and deadliest is the 1906 SF earthquake, 7.8 killing 1200 people.

We have met the enemy, and he is us — Pogo

by Migeru (migeru at eurotrib dot com) on Fri Feb 29th, 2008 at 05:29:06 AM EST
[ Parent ]
The earthquake region affecting Germany is the intra-plate rift Rheingraben = Rhine valley rift, especially its section near Cologne (Kölner Bucht).

The most powerful recent quakes were

  • in 1756 at Düren (6.2, two dead)
  • in 1951 at Euskirchen (5.7-5.8, no dead)
  • in 1978 at Onstmettingen (in Baden-Württenberg, 5.7)
  • in 1992 at Roermond/Netherlands (near both Belgium and Germany, 5.9-6.1, no causalties)

The last two deadly quakes were in 1878. Though no 7.0, 6.4 is thought possible near Cologne.

However, I recall reading an article by some geologists critical of the ruling assumption that the central part of the rift zone shifts in a 'lubricated' way -- that assumption is unproven, and that would imply the possibility of strong earthquakes with a low frequency. I.e., what the USA had at New Madrid in 1812 (incidentally the strongest for the contiguous states in recorded history), and China at Tangshan in 1976. Such low-frequency events are definitely missing from risk calculations, especially for high-rises, which haven't been around for long.

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Fri Feb 29th, 2008 at 06:27:57 AM EST
[ Parent ]
earthquakes. No major earthquakes have occurred since 1908 in Italy, none in Spain, Switzerland or Austria. I didn't know about the 1969 one in Portugal, although 11 of those deaths apparently happened in Morocco. Notably, Portugal began designing earthquake resistent buildings after 1755.

We know that large magnitude events have occurred prior to the 20th century. Has modern architecture (eg. flats and office blocks) in these countries withstood a direct hit of major earthquakes? No - because they're untested. There were no major events in this time period. And Messina was bad enough.

Developments and architecture work on hindsight, retrospection and, worse, amnesia - not foresight. I've used the housing planning in England's river stormbeds during last year's floodings as example of that. I don't believe it's really that different for earthquakes.

by Nomad on Fri Feb 29th, 2008 at 06:58:09 AM EST
[ Parent ]

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