New type of earthquake discovered – Hybrid-frequency waveform earthquake (EHW)

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A team of researchers from Canada and Germany discovered and documented a new type of earthquake in an injection environment in British Columbia, Canada. The recently discovered seismic events are slower than conventional earthquakes. Their existence supports a scientific theory that until now had not been sufficiently substantiated by measurements. The researchers named the new type of earthquake as hybrid-frequency waveform earthquake (EHW).

Unlike conventional earthquakes of the same magnitude, these newly-discovered earthquakes are slower and last longer.

They are a new type of induced earthquake triggered by hydraulic fracturing, a method used in western Canada for oil and gas extraction.

With a network of eight seismic stations surrounding an injection well at distances of a few kilometers, researchers from the Geological Survey of Canada, Ruhr-Universität Bochum, and McGill University recorded seismic data of approximately 350 earthquakes.

Around 10% of the located earthquakes turned out to exhibit unique features suggesting that they rupture more slowly, similar to what has previously been observed mainly in volcanic areas.

To date, researchers have explained the occurrence of earthquakes in the hydraulic-fracturing process with two processes.

The first says that the fluid pumped into the rock generates a pressure increase substantial enough to generate a new network of fractures in the subsurface rocks near the well.

As a result, the pressure increase can be large enough to unclamp existing faults and trigger an earthquake.

In the second process, the fluid pressure increase from injection in the subsurface also exerts elastic stress changes on the surrounding rocks that can be transmitted over longer distances. If the stress changes occur in rocks where faults exist, it can also lead to changes that cause the fault to slip and cause an earthquake.

Recently, numerical models and lab analyses have predicted a process on faults near injection wells that have been observed elsewhere on tectonic faults.

The process, termed aseismic slip, starts out as a slow slip event that does not release any seismic energy. The slow slip can also cause a stress change on nearby faults that causes them slip rapidly and lead to an earthquake.

The lack of seismic energy from aseismic slip and the size of the faults involved make it difficult to observe in nature.

Researchers have therefore not yet been able to document aseismic slip broadly with any association to induced earthquakes.

The work of the current study provides indirect evidence of aseismic loading and a transition from aseismic to seismic slip.

The team interprets the recently discovered slow earthquakes as an intermediate form of a conventional earthquake and aseismic slip – and thus as indirect evidence that aseismic slip can also occur in the vicinity of wells. They dubbed the events as hybrid-frequency waveform earthquakes (EHW).

While the shaking from a conventional earthquake of magnitude 1.5 in the researchers’ data set had died down after about seven seconds, an EHW earthquake of the same magnitude continued to shake for more than ten seconds.

References:

  • New type of earthquake discovered – RUB
  • "Fluid-injection-induced earthquakes characterized by hybrid-frequency waveforms manifest the transition from aseismic to seismic slip" – Hongyu Yu, Rebecca M. Harrington, Honn Kao, Yajing Liu, Bei Wang – Nature Communications, 2021, – DOI: 10.1038/s41467-021-26961-x – OPEN ACCESS

Featured image credit: Authors, NatureCommunications

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4 Comments

  1. KD- I agree fully that EQs are not caused by fracking/cracking BUT I have seen through the years that the path of the fault lines the EQ frequencies follow has changed, albeit not by very much. Rather than the pressure release points being natural edges of faults, the energy has an easier path now with weak points being introduced.
    The scientist in general but in particular the Federal government employees scientist have absolutely gone off the deep end. Their original function with you provide information education and warnings to their public who pays their salaries to keep us safe. They couldn’t do a better job of putting us in danger if they tried. Hiding earthquakes, downgrading earthquakes, removing webcams from the public View, and then making sure that none of these natural stories from here in America or internationally ever get into the media. The National Weather service’s manipulation of weather and climate data is Criminal and should be treated as such seeing as how it’s cost of world trillions of dollars and whether exactly in the opposite direction of what needed. The worst part is, as stupid and ineffective as they seen, their plan has worked… The public is entirely ignorant of any of the disasters happening either in their countries or abroad. As the internet is now synonymous with our federal government and big business oh, it’s no wonder they were able to accomplish such a complete censorship. As of right now I can’t even pull up in a world satellite map, every app and website will only show me my little area here in Texas. Small- minded BS, I’m so angry. Glad that youre informed…

  2. Science is lost. All ran by bought and piad scared little rabbits affraid of losing their funding. Not caused by fracturing. This is bold faced lie made up specially for the nwo’ control freaks of nature and their newborn brainwashed greenies.

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