Depending on the frequency range filtered out, the rockfall triggering the tsunami can be seen as a single peak (top), the standing wave sloshing back and forth as an undulating pattern in the recordings (middle, with several hours depicted) or the overall signal of the rockfall and the tsunami over the course of a week with strongly decreasing intensity of the oscillations (bottom). Credit: adapted from The Seismic Record (2024). DOI: 10.1785/0320240013
Standing wave persisted for an unusually long period
Such standing waves and the resulting long-period signals are already known in research. Such VLP signals are normally associated with large break-offs from glacier edges.
“In our case, we also registered a VLP signal,” says Carrillo Ponce, adding that “the unusual thing about it was the long duration.”
What was particularly impressive was that the data from seismic stations in Germany, Alaska and other parts of North America were of very good quality for the analysis. A comparison with satellite images confirmed that the cause of the first seismic signals corresponded well with the strength and direction of the rockfall that triggered the megatsunami. In addition, the authors were able to model the slow decay and the dominant oscillation period of the VLP signals.
This gives the researchers hope that they will be able to detect and analyze other similar events from the past. It is obvious that the retreat of glaciers, which previously filled entire valleys, and the thawing of permafrost are leading to increased landslides. Climate change is accelerating the melting of glaciers and could therefore increase the risk of megatsunamis.
More information:
Angela Carrillo-Ponce et al, The 16 September 2023 Greenland Megatsunami: Analysis and Modeling of the Source and a Week-Long, Monochromatic Seismic Signal, The Seismic Record (2024). DOI: 10.1785/0320240013
Provided by
Helmholtz Association of German Research Centres
Citation:
Landslide triggers megatsunami in narrow fjord (2024, August 8)
retrieved 8 August 2024
from https://phys.org/news/2024-08-landslide-triggers-megatsunami-narrow-fjord.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.
Source link : http://www.bing.com/news/apiclick.aspx?ref=FexRss&aid=&tid=66b5184e9bf84f539e98ea6cee79d101&url=https%3A%2F%2Fphys.org%2Fnews%2F2024-08-landslide-triggers-megatsunami-narrow-fjord.html&c=3135613955206854505&mkt=en-us
Author :
Publish date : 2024-08-08 08:00:00
Copyright for syndicated content belongs to the linked Source.
