The same applies to Italian Alps, with some villages almost garanteed for natural destruction in the near future. And also in France, above Chamonix, where massive internal pockets of water due to melt forming- which could destroy places like St Gervais in a matter of minutes.
''But the serenity is deceptive. In the core of the glacier lies a silent threat that could, without warning, destroy the village of Saint-Gervais below. Trapped under the glacier lies an enormous 65,000 cubic metre pocket of water – the equivalent of 20 Olympic swimming pools – that could burst and surge down on to the village below. "It's impossible to predict when that might happen," said Christian Vincent from the Grenoble Laboratory of Glaciology and Geophysical Environment. He is here to carry out a regular temperature check at Tête-Rousse.
The 75 metre-deep glacier covers 8 hectares of a rocky basin. Early this summer, several boreholes were pierced with a high-pressure hot water drill and special sensors introduced on to the bedrock. Using a snow shovel, the scientist clear the markers that show where these were placed and note down the temperatures. "Precise knowledge of a glacier's temperatures is vital to understanding how these water pockets are formed," Vincent explains.
The danger may be invisible but it is real enough. One such disaster remains in Saint-Gervais's collective memory. In 1892, 80,000 cubic metres of water that had collected in a sub-glacial cavity burst through the ice "cork" that was holding it in. A torrential flow of water tore down rocks and trees in its path and buried Saint-Gervais in mud and debris, leaving 175 dead.
According to the current mayor, Jean-Marc Peillex, far greater damage would be caused now, "due to urbanisation and the large number of tourists visiting the glacier". As many as 900 houses could be swept away.''
Permafrost melting? This is more related to events like the landslide back on 2017 on the Piz Cengalo that disappeared 8 hikers and destroyed Bondo (GR). In case anyone does not knows the story, the top of Piz Cengalo is above 3'500 meters and the destroyed village is at 800m above sea level.
Karst is different. It's cavities in very soluble rocks like gypsum and limestone. Over 25 years, the only case I've seen is cavities appearing around and below locks in a river in gypsum rock. Also under dams with 100 or 200m of water that weren't there before. Otherwise, karst cavities take centuries to develop. If a house or building is affected by karst, it's because the subsoil with cavities collapses under the weight of the human made structure. But the cavity, was already there, not caused by the construction.
That is not how it works. Foremost, it is the land owner who is liable. That is why you must make sure the company that you contract indemnifies you for any damages. If they don't make sure you have your own liability insurance. Which, if you are doing any construction work you should have anyhow.
We had a similar situation where we were liable for any damage to the street by a crane. We made sure the crane co takes over liability for damages.
Yes, I live on limestone- the Jura. We have sink holes everywhere- and even one which was exploited as the only row of mills, housed vertically. Limestone certainly does not hold huge internal glaciers and pockets of water- for obvious reasons. We are talking about the Valais here, the Alps, where internal glaciers, like the surface ones, are melting. When it happens out of sight, as above St Gervais-it is a disaster in the making (well it destryoed many in the past, and recently a disaster has been averted, but ...)
It is also a very seismic zone.
Earthquakes in the Valais
More earthquakes occur in the Valais than anywhere else in Switzerland. The region therefore has the country's highest seismic hazard, although Switzerland's strongest known quake occurred in Basel (Basel 1356).
Over the past 10 years, the SED has recorded an average of around 270 earthquakes per year in the Valais and its immediate surroundings.
I'm an irredeemable optimist in this case. I think a lot of of work has been done to determine risk areas in the Alps. From snow/ice avalanches, to earthquakes and landslides.
Anyway, we're humans and I'm sure houses here are valued 2-3 million or more. Valais is not an exception, humans also value seafront homes in hurricane zones at ridicule prices
If the African plate had not been pushing for million of years against and below the Eurasian plate there would not be beautiful and majestic Alps in first place.
The interesting part is that people still lives in traditional houses with poor resistance to earthquakes. It's a complicate issue where feelings and an attitude of "who do I believe, the scientist or my eyes?" are involved. All centuries-old constructions that have not been made earthquake-proof by now are death traps for the next big earthquake. The experience from l'Aquila in Italy back on 2009 should be something to learn.
Anyway, all these geological phenomena has happened before humans. Yes, burning fossil fuels increases CO2 in the atmosphere, but drilling a borehole for a geothermal heat pump will not trigger a catastrophic landslide. That's giving ourselves humans too much importance. Back to OP's issue, I guess it's just envy and being worried about competition for a scarce resource.
I'm not building in Valais but Schaffhausen, where any kind of permafrost is a non issue.
I have building insurance (which covers up to 400m holes) and also from the canton I have another insurance. Plus the driller will have insurance.
The threats are hollow, even if an entire building of 15 people has made them. It will not block anything and I am in no obligation to pay for crack assessments at 1k per block before/after the drilling.
Their letters will simply go unanswered, since I know from past experience of these hollow threats (my neighbour complaining about tree roots damage on my land) the town doesn't even send these people my answer.
The eventual update on this is that we received complaints I think from almost everyone who was notified. My wife now feels we will enemy number one in the neighbourhood, even if I reasure her this is quite normal.
Could it be that since several, not so close neighbours also have geothermal, they don't want me stealing their heat.. Maybe..
But maybe someone here could shed some light. They put in the complaints to the town. I think such complaints were raised against the other geothermal drillings in the neighbourhood also, so it was to be expected. But they also went ahead since these complaints can't stop the process.
Then why put in the complaints in the first place?? The town expects us to reply to them only, replies to neighbours are optional if we want they said (we won't).
I think perhaps this might be a requirement if they were to raise claims against the insurance company for damages perhaps. But this is my guess. They will also need to have completed the "risk protocol" which is their crack inspection before and after the drilling takes place for any claims.
Having exchanged emails with casafair home owners association to ask their advice, they are of the same thinking about this going nowhere.