Monitoring seismic slip on the Mam Tor Landslip

Abstract

Loan 802 had a two-fold aim: to ascertain whether seismic events were associated with the movement of the Mam Tor landslide and could help with our understanding of sliding mechanisms; to field test the then new Guralp DCM recorder. From the 19th December 2006 to 9th January 2007 a CMG-3T sensor was deployed in a vault on the Mam Tor slip, whilst a second control sensor was placed a few hundred metres away, off the slip, in farm buildings. Surprisingly, correlation of waveforms with significant slip events on the co-located Manchester University’s strainmeter showed no demonstrable evidence of seismic emissions. We deduce that Mam Tor is moving as an aseismic ‘slurry’ at rates out-with the period band of the CMG-3T (>>120s). An undergraduate at Leeds University determined receiver functions for the two sensors as part of his independent project. Despite the very different superficial conditions on and off the slip, he showed that the receiver functions for sensors only few hundred metres apart were in fact very similar. The velocity-depth structure of the crust determined by modelling the receiver functions was similar to the LISPB model. Specific developments with Guralp on the DCM resulting from this project include: 1) producing reliable communication with recorder, 2) enabling locking of 3T and 3TD sensors without serial communication. 3) an understanding of the optimal DCM data recording parameters, 4) using autonomous systems without battery charge capability. This preliminary loan led to a NERC small grant proposal (Sept 2007) entitled ‘Monitoring seismic slip on the Mam Tor landslide PIs (Prof. E. Rutter, Manchester University; Prof. G. Stuart, Leeds University; Dr Brisbourne, Seis-UK). Unfortunately this grant was unsuccessful.