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New Insights on the Åknes Rockslide (Norway) Using Borehole Microseismic Data

Description: 

The Åknes rockslide, located in Western Norway, is one of the most thoroughly instrumented rockslides in the world. Since the 2000s, it has been equipped with various instruments measuring its displacement (extensometers, GPS, lasers,…). Measured movements are in the order of 1 to 3 cm/yr.

As part of the monitoring system, eight geophones were installed at the surface around the backscarp of the slide in 2005. Although the data are only recorded in triggered mode, the large amount of data collected over the years has proven useful to characterize different types of events related to the slide movements.

More recently, a borehole was instrumented with eight geophones continuously recording at 1000 Hz down to a depth of 50 m, crossing two sliding planes. There, seismic events characterized by a very high frequency content and a short duration can be detected. These events are likely located very close to the borehole. In particular, periods of intense seismic activity could be identified. The detailed analysis of the waveforms during such periods reveals series of repeating events interrupted by quiescence phases that could be interpreted as creeping on different patches of the shear zone. At least one of these periods could be correlated with an increase in the water pressure at the depth of the corresponding shear zone.

Session: Detecting, Characterizing and Monitoring Mass Movements - III

Type: Oral

Date: 5/2/2024

Presentation Time: 02:30 PM (local time)

Presenting Author: Nadège

Student Presenter: No

Invited Presentation: 

Authors