Nuugaatsiaq Greenland landslide and tsunami: Seismograms suggest several stages of land failure

Quake Stories

Seismograms around Nuugaatsiaq Greenland landslide image a complex source process lasting about 2 minutes.

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3 component seismograms available from IRIS for stations from about 30 to 500km from the Nuugaatsiaq landslide are shown below.  The traces are aligned (vertical red line) on a distinct, ~5sec pulse on the transverse component (magenta traces).  Seismic phases from the USGS origin for the landslide (To, P, Lq, Lr) identify this pulse as a Love wave (Lq) from the source.


A few seconds after this pulse is a similar pulse on the vertical (cyan) and radial (yellow) traces, this signal can be identified as the Rayleigh wave (Lr) from the source. [The misalignment of the predicted Lq and Lr times with the pulses on the seismograms can be attributed to the ~20km offset of the USGS epicenter to the NNW of the landslide, and to specifics of the Greenland crustal geology.]

What is striking…

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