Understanding natural and man-made earthquakes

What fascinates Stefan Wiemer about earthquakes and his job as Director of the Swiss Seismological Service and why he wanted to be engaged in a collaborative EU project on geothermal energy.

It was a quiet Sunday morning in October 2016 up until the moment when Stefan Wiemer received the alert announcing an earthquake with a magnitude of 1.9, five kilometres beneath Basel; a small earthquake most likely not felt by the population. As the Director of the Swiss Seismological Service SED, earthquake alerts reach him quite often at any given time. More than 150 seismic stations all over Switzerland measure the slightest movements in the underground and immediately send the data to the central analysis computer in Zurich. 

«For me earthquakes are
the most interesting topic.
They are so little understood
and may yet be so devastating.»

The computer screens the data for a possible earthquake and automatically generates alerts to the authorities, media and public within about 45 seconds. The computer also alerts a team of two scientists and an IT specialist who are on a 24/7 duty to oversee the monitoring of the seismic activities in Switzerland and around the world. Stefan Wiemer is informed but not always actively involved in communications, except if there is a larger earthquake like the one in central Italy in August 2016 that killed nearly 300 people. After this seismic disaster, the SED had to handle more than 40 media inquiries and the Director and members of his team gave dozens of interviews. “Media and authorities usually want to know exactly what has happened and all about the relevance the incidents have in relation to Switzerland,” Stefan Wiemer says when we meet him in his office at the Department of Earth Science at ETH Zurich. 

Understanding earthquakes 

Stefan Wiemer has been a passionate seismologist since his days as a student of geophysics at the Ruhr-Universität Bochum, Germany. “I became more and more fascinated by seismology because for me, earthquakes are the most interesting topic. They are so little understood and may yet be so devastating,” he says. So he devoted his research career to a deeper understanding of the mechanisms of earthquakes; why they occur, when they occur, where they occur and if they could be predicted at all. But apart from the scientific challenge he also likes the practical implications of his research field. He often sees himself as a mediator between science and the public. “What we do in research and by monitoring the underground matters greatly to people. They are fascinated by and at the same time worried about earthquakes. 

«Buildings kill people, not earthquakes.
The best protection is to make
our constructions more resistant.»

We try to communicate what happens beneath the surface of the Earth in an understandable way. We also evaluate and publish the seismic hazards and give advice on how we can protect ourselves, which has a very practical meaning. I like this combination of research and service to the society very much,” Stefan Wiemer states. 

The link between science and public service was reinforced after a so-called man-made earthquake that shocked Basel in December 2006. This earthquake, with a magnitude of 3.4 along with thousands of smaller ones, was induced by the Deep Heat Mining Basel project during the creation of an underground heat exchanger at a depth of five kilometres. At that time, there was great optimism in the community of Earth scientists to harvest clean geothermal energy by pumping water into the deep and heat it up down below. However, after the Basel incident and a similar one in St. Gallen many of these projects were put on hold. Ever since, the public has been reacting rather sensitively on any plans to exploit deep geothermal energy. That small earthquake near Basel on that quiet Sunday morning in October turned out to be a late reaction to the pilot drilling in 2006 – this is why Stefan Wiemer got involved personally when he received the alert and contacted several people from the local authorities. 

Soft technologies for geothermal energy 

Nevertheless, also in Switzerland geothermal energy has a great potential as part of the future energy mix, as it is clean and abundant. The challenge is to find technologies able to harvest the heat under our feet in a safe and sustainable way. “We are looking for soft stimulation techniques that make the heat exchange in the underground environmentally friendly, safe and sustainable in the long term,” Stefan Wiemer explains. This is precisely the objective of the EU project called DESTRESS, in which Stefan Wiemer and his team play a crucial role. Actually, he has been one of the initiators. When the call was published by the EU, he took action immediately. “I always felt it is important that Switzerland is part of such a project. We had geothermal experience in the past; we have plans for the future and are relevant players in this field. So eventually, I picked up the phone and talked to my colleagues at the Helmholtz Centre Potsdam and to Geo-Energie Suisse AG, a company focused on realising geothermal projects in Switzerland. We invited additional partners to a preliminary meeting, then we wrote a proposal and that is how the initial idea matured and became an EU project,” Stefan Wiemer recalls. DESTRESS is a large collaborative consortium that brings together science and industry on a large scale. As the focus lies much on testing and demonstrating new soft stimulation techniques at various sites, the industry assumes a strong part and communication beyond borders is quite a challenge for all of the project’s participants, as Stefan Wiemer illustrates: “When we as scientists talk about exploiting geothermal energy, we talk about induced seismicity and about risks. Industry likes to emphasise much more on the potential benefits and the costs.” Within the consortium, he and his SED communication team lead the working group “Dissemination and Communication”, ensuring that the different perceptions of operators and scientists are openly discussed and evaluated. 

«When we as scientists talk about
exploiting geothermal energy,
we talk about induced seismicity
and about risks.»

Based on this information, society and authorities will weight risks against benefits and ultimately decide on new technologies. Regardless of the result thereof, DESTRESS offers a great opportunity: It enables scientists and operators to apply and closely monitor soft geothermal energy harvesting technologies, which are safe, economically liable and sustainable. “Today, we are missing a common baseline dealing with the best possible way to approach reservoir stimulation. At the closure of this project, one can at least decide whether these technologies may work. So DESTRESS is part of the solution,” Stefan Wiemer concludes. 

Managing earthquake hazard 

Whatever the outcome of DESTRESS, Stefan Wiemer and his team are profiting now already from participating in this project. Three additional postdocs and one communication specialist financed by DESTRESS allow Stefan Wiemer to pursue his research and to contribute meaningfully to the project. These resources would not have been sponsored by any other funding agency in Switzerland. But the true value is beyond money, as Stefan Wiemer states. “The real worth is the cooperation with partners in Europe and Asia. It enables us to exchange views and to bring our ideas and equipment to their sites and vice versa. This hopefully will accelerate the development of novel techniques and better solutions.” In future, the danger of earthquakes induced by geothermal energy projects may disappear or at least be under control. But what about the hazards of natural earthquakes? “Buildings kill people, not earthquakes,” Stefan Wiemer states. “The best protection is to make our constructions more resistant. When constructing new buildings, just a small additional investment significantly enhances earthquake safety. We just have to do it!”

Interview with Stefan Wiemer