Last night, 18th July 2019, VITO gave an update to 200 local residents about the deep geothermal project after the earthquake of 23rd June 2019.

Dirk Fransaer, Managing Director of VITO, repeated the aim of this research project: to investigate whether Flanders can use geothermal energy as a climate neutral energy source in the energy transition. For heating buildings and to produce electricity without green power certificates at a competitive price. Ben Laenen, research manager at VITO for this project, gave more information about the earthquake, the actions that were taken and the next steps. The local residents of Mol and Dessel had the opportunity to ask questions and Wim Caeyers, the mayor of Mol, concluded the meeting.


The construction works for the deep geothermal central of the Flemish research organisation VITO, at the Balmatt site in Mol are finished. The site in Mol, in the Kempen region, is the very first geothermal doublet in Belgium. For this doublet, two wells were drilled, at respectively 3 610 and 3 830 meters deep.The installations at the Balmatt site were temporarily delivered in May 2019. In a relative short period of time, the project team has succeeded to make up a modus operandus to produce green heat 24/7.  The Balmatt central produces salt water with a production temperature of 120 °C. After use of the heat, the water can be reinjected in the subsoil at about 60 °C so that a thermal power of 4-5 MW can be produced. The possibilities exist to double this capacity in the future depending on the heat demand. In first instance, for now the surrounding company buildings of VITO, SCK•CEN and Belgoprocess are heated through the heat network. The remainder of heat is used for the production of electricity through an Organic Rankine Cycle (ORC). On 21st June 2019 the central has stopped because of a drop of electric tension on the general electricity grid. 2 days after ending the longest operational period, an earthquake has occurred with a magnitude of Ml=2.1 close to the injection well MOL-GT-02. The project team has then started an examination based on the data from the own seismometer network and has called upon a German partner to investigate further what exactly has happened in the deep underground.


Since the first test phase in November 2018, in total 265 vibrations with MI = -1,0 – 2,1 have occurred, all around the injection well. At the trembling of 23rd June 2019 a surface of  1 600 m²  at a vertical depth of 3 500 m has moved 1 to 1,5 cm. The cause is a sudden discharge of the pressure that has built up underground at the pumping back of the cooled water. The data that VITO has collected is now being verified with other models and foreign experts are comparing these results with other geothermal projects. Based on this, the ‘Traffic Light System’ will be updated and the chances for vibrations higher than 2,1 on the Richter scale are limited.

Avoid noticeable earthquakes

VITO is using a ‘Traffic Light System’ or TLS to manage the risk of noticeable earthquakes at the surface. This TLS is based on 4 parameters: the calculated magnitude of an earthquake, the epicentre of the trembling, the number of tremblings per time unit and the maximum measured ground acceleration in the seismometers from the monitoring network. For each parameter, limiting values are defined that mark a green, orange and a red zone. When at least one of the parameters is in the orange zone, the parameters in the geothermal central like flow and injection pressures are slowly reduced. When at least one parameter is in the red zone, the central will be stopped temporarily. Insights will lead to the adjustment of the limiting values and the improvement of the Traffic Light System step by step.

Restart of the central

At the moment, VITO is analysing possible damages to well 2 and activities are started to reduce the chance of earthquakes. In the meantime, also the heat networks to IRMM-European School and Atoomwijk are being planned.

For more information:

Ben Laenen – – Tel.: 014 33 56 38