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Erdbebengefahr durch verdeckte Verwerfungen: Institut für Geologie erprobt neue Indikations­verfahren

Earthquake risk from blind faults: Institute of Geology tests new indication procedures

The photo reveals standing disaggregation bands formed in young, unconsolidated and near-surface sediments in northern Denmark. In this area there is a large fault in the subsurface, which has been detected by geophysical measurements. Earthquakes have occurred on this fault in the past.

In cooperation with the Leibniz Institute for Applied Geophysics (LIAG), Dr Christian Brandes from the Institute of Geology has developed a method to detect recent tectonic activity from hidden, blind faults. Their work was published in the journal "communicatinos earth & environment", which is part of the Nature portfolio.

Faulting is the term used to describe areas where two volumes of rock or parts of the earth's crust occur offset from each other or even pushed up. One well-known fault is the San Andreas Fault in California, USA. It illustrates the potential hazards that faults can pose for seismic activity.

The team of researchers investigated outcrops above known faults in Germany and Denmark. They were particularly interested in the so-called disaggregation bands. These bands are formed in a similar way to faults, but in being close to the surface and easily accessible, they can provide important information on neotectonic activity in the subsurface. Especially for the identification of hidden faults in earthquake hazard maps, this work provides an important new approach. Even creeping faults, which currently show no activity but could cause earthquakes in the future, can be detected using disaggregation bands.

Explore hidden hazards

"Blind faults can have particularly large consequences because they are often unknown and earthquakes occur unexpectedly," explains Dr Christian Brandes. "There are still many hidden faults whose position and activity could not be precisely determined until now - because detecting especially creeping faults was only possible with the help of permanent observations at the surface." Dr. David Colin Tanner, geologist at LIAG, adds: "Often, targeted observations are only made where earthquakes have already occurred. However, in northern Germany, for example, there are also stresses in the subsurface caused by the melting of the glaciers at the end of the last ice age, which have led to a still ongoing but often underestimated activity phase of faults. Future analyses of the hazard potential of known faults would need to take the new findings into account."

The research team received further confirmation of their findings from simulations using a shear apparatus as well as computed tomographic techniques. The German Research Foundation (DFG) is funding a project to study an active fault in New Zealand, where methods can be further developed and refined to make reliable predictions of hazard potential.

  • Press release of the LIAG
  • Publication in communications earth & environment: Disaggregation bands as an indicator for slow creep activity on blind faults