Tuesday, April 2, 2013

Landslides leave a seismic signature


Scientists have long used seismometers to gain information about earthquakes, deciphering what happened and even estimating possible damage. But, that’s not all they can do. If you’ve ever walked past one (or, well, jumped around in front of one to watch your own seismic signal…and yeah, go do that if you haven’t, check the links at the bottom for more), you know that seismometers pick up many signals, even from small movements like people or trucks moving by.

Modern seismometers are programmed to recognize these small shakings and filter them out in the hunt for the signals from actual earthquakes. But what if they were filtering out information on a threat to people which could be detected, like a landslide?

Large landslides shake the ground enough to give substantial seismic signals, but most landslide signals aren’t recognized by seismometers. New research in the journal Science seeks to change that.

The researchers, led by Lamont-Doherty Earth Observatory, took seismic data on the largest landslides and found trends within the data. Just like seismologists can classify earthquakes and tell where they happen based on seismic data, these researchers found they could interpret landslides in much the same way.

The different portions of a landslide: breaking away, traveling down a steep slope, shallowing and traveling across a flat area, landing in a ravine, all give distinct seismic signatures. The recorded seismic data even could give the size of the landslide, all in real time.

The group even found that what was once thought to be a single slide in India based on the deposit was actually a series of seven distinct landslides over four days.

Some obvious future applications could be determining areas where a slide has blocked a river, threatening commerce or creating a flash flood risk or in determining where to send resources after a major storm.

Landslides kill thousands of people per year. Taking this data and turning it into an accurate warning system or helping further understanding of the conditions that give rise to a slide will be challenging, but if the seismic stations are already in an area, or the area is very prone to landslides, this research could help develop systems that will save lives worldwide.


ScienceNOWarticle:
http://news.sciencemag.org/sciencenow/2013/03/the-shaky-side-of-landslides.html

Original paper:
http://www.sciencemag.org/content/339/6126/1416

Perspectives article:
http://www.sciencemag.org/content/339/6126/1395.summary

Landslide in the Philippines, image source:
http://thewatchers.adorraeli.com/2011/07/28/philippines-on-alert-for-landslides/

Landslide death toll, from Nature:
http://www.nature.com/news/death-toll-from-landslides-vastly-underestimated-1.11140

Turn your computer into a seismometer:
http://qcn.stanford.edu/sensor/

No comments:

There was an error in this gadget