10 October 2018
Two developing large landslides – Mannen (again) and Diamante
Posted by Dave Petley
Two developing large landslides – Mannen (again) and Diamante
News today of two interesting landslides under development, at Diamante in Argentina and Mannen (once again) in Norway
Diamente
Diamante is, according to Wikipeda, “a city in the west of the province of Entre Ríos, Argentina, on the eastern shore of the Paraná River. It has about 20,000 inhabitants as per the 2001 census“. Over recent weeks a large tension crack has developed, defining a block some 130 m long, causing the evacuation of 60 families. Concern was raised about the incipient failure on Saturday, since when the incipient landslide has continued to develop:-
A part of the large tension crack at Diamante in Argentina. Image via infobae.com
.
Mannen is creeping again
Meanwhile, in Norway our old friend the Mannen rockslope failure is moving rapidly once again. This large incipient rockslope failure has gone through a number of periods of accelerated creep, but yesterday the rate of movement increased to about 40 cm per day in the upper part of the slope. This has been associated with increased rockfall activity, which is generally an indication of increased deformation of the creeping rockmass as strain develops. Overnight the rate has increased a little more, reaching 2 cm per hour. As a consequence, the long suffering residents were evacuated once again, the fifth time since August, and the tenth time since 2014.
Scematic diagram showing the Mannen landslide in Norway. Image via NVE and NRK
.
There is a live webcam showing the site in this newspaper report. Should failure occur it is estimated that the landslide will have a volume in the range of 120,000 to 180,000 m³. NVE has a webpage that is providing regular updates on the landslide, including screenshots of the monitoring data.
The challenges of forecasting failure
In both cases the problems with forecasting future behaviour are well-illustrated. Evacuating the local people is essential at each of the two sites, but the geologists will be very aware of the impact that this will be having on the community. The experts will be feeling immense pressure, but there are huge uncertainties when trying to extrapolate future behaviour of natural slopes. It is frustrating for all involved.
Acknowledgement
Thanks to Donaldo for highlighting the Diamante landslide
Dave Petley is the Vice-Chancellor of the University of Hull in the United Kingdom. His blog provides commentary and analysis of landslide events occurring worldwide, including the landslides themselves, latest research, and conferences and meetings.
By deploying Critical Slope Monitoring Service (our model) IBIS-FM, perhaps with supporting SatSAR too — I see a lot of opportunities to well-inform local geoprofessionals, the townspeople, as well as local authorities.
At the Norwegian site, I am not sure what radar they are using and selecting only 3-4 “points” ???? But I know for sure we can monitor that slope very well, and provide advanced alerts and data for the community, giving them awareness and confidence.
I can see also a nice line-of-site for the slide in Argentina. Super easy to deploy an IBIS and monitor this slope. It also looks viable for information from available SatSAR libraries.
We take a need and put the resources on it to provide near real-time data and decision-making support. If folks at either location need more information, please get in touch .. there is NO reason not to avail the technologies and methods to raise safety opportunity, inform residents and local officials, and support the local geoprofessionals with actionable data. john — 303-726-6024 or [email protected]
Our efforts to establish the idea of Critical Slope Monitoring #CSM have been successful, where implemented and feature a radar instrument with <2 minute differential scans, software to manage and offer an analysis interface #Guardian, a Risk Matrix, a Hazard Map index, and system configurable (user) alerts by screen, SMS, and E-mail. A Trigger Response Action Plan TRAP, that all parties sign and live by during the monitoring period — this elevates the data to actionable levels and allows safety consideration and operational decision-making to become regular and a reference for physical actions of the at-risk community. It was described in a recent poster presented at Virtual Geoscience 3 (2018) at Queens University, in Kingson, Ontario. https://www.linkedin.com/feed/update/urn:li:activity:6439205996052254720