DAY SIXTY ONE The Earth Beneath Our Feet
Over a large slice of Prinzregententorte this morning, I tried to engage the Race Marshal on the subject of the Rhine rift valley. I tried hard to explain why this ancient tract of sunken land is so interesting. I pointed out the beauty that was to be found as the rift runs its 350 kilometre course south from the upper reaches of the Rhine, cutting through opposing bastions of the Jura and the Black Forest to the Alps - but that failed, too. The truth is that she is not much interested in geography, much preferring biography. Perhaps that's because geography is about maps while biography is about chaps.
Rift valleys have held a fascination for me since the mid-1980s when the Independent sent me off through a fragmenting Soviet Union to Vladivostok. En route, I swam in Lake Baikal, my corporeal presence quivering 5,387 feet above the bottom of the lake, hoping the ghostly golomyanka would not start their rise from the depths. Baikal is itself a rift valley that, as it dropped, cut a river in half - so one part of the river fills the lake (Baikal holds one-fifth of the world's non-frozen fresh water) and the other part empties it.
As an aside on Vladivostok, the city port then was very run down. The prison was a hideous stockade of corrugated iron and the back wall of the Soviet naval command was hanging off. One dared not produce a cigarette: here at the end of the Trans-Siberian Railway, supplies came in only occasionally. But there was a high point. I had arrived two days before the US Pacific Fleet came to pay its first courtesy call since 1945. Taking myself down to the port, I stood at the foot of a destroyer's gangplank as its sailors disembarked. I shook their hands as they came down and welcomed them to Vladivostok on behalf of the British Empire.
As in most rift valleys, there is seismic activity around Baikal: in 2015 alone, there were more than 50 major tremors along the north shore that ranged from 3.0 to 5.0 on the Richter Scale. In Europe, too, the earth is unquiet: over the past eight centuries, in Switzerland alone, there have been 10,000 earthquakes, a handful of which have registered more than 6.0 on the Richter scale.
During the past seven days in Germany, there have been 19 quakes - the one on Friday 12th June registered 2.6 on the Richter scale. This event started ten kilometres under the town of Koblenz – about 80 kilometres north of where we are in Heidelberg. One person living near the epicentre wrote in to say:
I lay awake since 3 am due to a bad dream. At a quarter to four I felt the house quiver and shake very slightly. I immediately knew it was a light earthquake as a I have grown up in this area and am sufficiently acquainted with small earthquakes.
Whatever hundreds of seismometers across Europe may tell us, there is apparently nothing to worry about because while seismic events occur regularly where tectonic plates touch, intraplate activity is rare. But rifts are, as their name suggests, weakenings of the plates and there are a significant number in Germany. What I have been calling the Rhine rift is only two sections of a broader sweep of 'thrust faults', collectively the European Cenozoic Rift System, created some thirty million years ago when the plates of Africa and Europe collided and pushed up the Alps and the Pyrenees.
As far as seismic activity is concerned, I tend to see the glass half empty. It concerns me that the faults along the Rhine are responsible for most of the larger earthquakes in Europe. At the southern end of the rift there is also evidence of volcanic activity - a range of volcanic hills known as the Kaiserstuhl, the Emperor's Chair. Another chain of extinct volcanoes known as the Vulkan Eifel stretches over to Trier on the border with Luxembourg. In this range, near Koblenz, is the Laacher See, a two-kilometre-wide lake filling a volcanic crater.
About 13,500 years ago, the Laacher volcano exploded with devastating force. All life within a radius of 60 kilometres was exterminated. For several years afterwards, the summers were cold and brought starvation to the Federmesser people who relied on hunting with spears, bows and arrows. As the Federmesser declined, two new peoples moved in - the Bromme from Scandinavia and the Perstunian from the north-east. These were lesser cultures without the tool-making skills of the Federmesser - no bows and arrows - and this was the stuff of dystopian nightmares: genuine cultural regression in the face of a cataclysmic event.
While these volcanoes may have been quiet since then, the European tectonic plate has not. There have been myriads of tremors over the centuries, the worst on record being the 1356 earthquake centred on Basel (at the southern end of the rift) which touched 7.1 on the Richter Scale and 'destructive/devastating' on the Medvedev–Sponheuer–Karnik index.
The inhabitants of Basel felt the first rumble at around eight in the evening and two hours later came the real quake. As the night progressed, there were many aftershocks - probably unnoticed by the people desperately fighting fires started by falling lanterns, candles and logs shaken from the hearth. The town of wooden houses was engulfed and three hundred people died. The shocks also flattened castles and churches, solidly built structures, for a radius of 30 kilometres and we don't know how many more were killed.
If, taking the glass half empty approach, there were to be a serious earthquake here, it would be catastrophic. With Basel again, say, at the epicentre, the French nuclear reactor at Fessenheim would be at risk. So too would the Upper Rhine aquifer that lies beneath the rift. This is one of the largest aquifers in Europe, holding 110,000 cubic miles of fresh water. The huge Lake Baikal holds only a twentieth of this volume - 5,670 cubic miles of fresh water. And at risk would be the villages and towns that either survived the war and are therefore mostly medieval, or were rebuilt immediately after the war without thought for seismic activity.
These days all new buildings are subject to specific seismic risk regulations, particularly stringent in seismic hot spots (such as where we are sitting). The fascinating Think Hazard website publishes maps indicating levels of seismic risk for various countries:
In the area you have selected (Germany) earthquake hazard is classified as medium according to the information that is currently available. This means that there is a 10% chance of potentially-damaging earthquake shaking in your project area in the next 50 years. Based on this information, the impact of earthquake should be considered in all phases of the project, in particular during design and construction. Project planning decisions, project design, and construction methods should take into account the level of earthquake hazard.
Think Hazard's seismic risk analysis - red shading indicates high risk
I suppose we should move to a modern-built hotel - but we can also take comfort from the fact that humans have survived on this precise spot on the European tectonic plate for 700,000 years. In fact, the oldest human remains on the continent, that of Homo Heidelbergensis, were found here in high-risk Heidelberg. It's not quite clear how his species and ours are related; he may have been an early Neanderthal or he may have been just one evolutionary step away from us.
homo heidelbergensis (c)naturalhistorymuseum
Relatives or not, his species had a brain almost as large as ours - so perhaps he too worried about the goings on deep beneath his feet. Sadly, our brainy but worried homo heidelbergensian would not have been able to calm himself, as I shall later, with a stein of Urmensch Bier (Prehistoric Man Beer) because, though the brewing lineage here is ancient, the local Heidelberger Brauerei was not going in 700,000 BC. But perhaps I do him a disservice: maybe he had a gourd or two of heidelbergensian cave-brew tucked away somewhere.
Anyway, I shall now get on my well-boiled icicle and go for a soothing ride. The Race Marshal is planning some kind of Corbusier outing - but I think the twin 750cc cylinders of her Harley will be necessary for that. My plan tomorrow is to pedal locally in the slip stream of the formidable Bertha Benz.
If you would like to feel uneasy, here is a film about earthquake zones in Germany - https://youtu.be/V30kkGb_B5A
The full movie of Krakatoa East of Java (1968) - https://youtu.be/Xvo90jU_CmA
And for some calm, here is Janet Newkirk's favourite recording: Murray Perahia playing Bach's English Suites - https://youtu.be/cOr74wVsTJw