Help Support EcoWatch
The best of EcoWatch, right in your inbox. Sign up for our email newsletter!
Tectonic Plates Reverse Their Movement Before Major Earthquakes
By Fabian Schmidt
Researchers have discovered an interesting similarity in two of the largest recent earthquakes in Japan and Chile: a strange large-scale ground movement back and forth in the months leading up to the quake.
These earthquakes are among the 10 strongest ever measured: the 2011 Tohoku-oki seaquake off the coast of Japan registered 9.0 on the moment magnitude scale, triggering the devastating tsunami that destroyed the Fukushima Nuclear Power Plant. It was the fourth-strongest quake in the last 100 years. The 2010 seaquake off the coast of the Maule region of Chile, occupies sixth place on the list.
Researchers from the Geoforschungszentrum Potsdam (GFZ) along with collaborators from Chile and the United States have now discovered astonishing similarities in the months before both quakes: multiple strange reversals of ground motion — an extremely slow "wobbling" of the continental plate, so to speak.
Lead author, geophysicist Jonathan Bedford, along with a team of geodesists, geologists and seismologists, evaluated the movements of ground stations of the Global Navigation Satellite System (GNSS).
These ground stations continuously track the distances to multiple GNSS satellites that orbit the earth in elliptical orbits. After these distances have been established, and given the estimates of the satellite positions, geodesists are able to define the motion of points on the Earth within a terrestrial reference frame.
In Japan, there is a very dense network of ground stations. Although the network in Chile was not as dense in 2010, it was sufficient to obtain the data.
Whole Continental Plate 'Wobbles'
Bedford and his colleagues analyzed how the ground stations in Japan and Chile had moved in the five years before the two quakes. They noticed that the motion of the continental plate on which the stations are located had been reversed several times in the last five months before the quake (in the case of Japan) and seven months (in the case of Chile). The researchers published their results in the scientific journal Nature.
Both plate boundaries are subduction zones. Subduction is the process of one plate diving under another. In both study regions, the oceanic plates are subducting underneath the continental plates and meet at a place called the trench, which for both cases is submerged under the ocean. Normally, the continental plate is pressed by the oceanic plate and thus pushed away from the trench. However, the geophysicists have now discovered that this movement was first reversed in the direction of the trench, then away from the trench, then back towards the trench again.
Same Movement Over Thousands of Kilometers
They call this phenomenon "wobbling," due to its appearance in the GNSS time series. The amplitude of this movement is not particularly great — it was only between 4 and 8 millimeters — but Bedford points out that this is significant compared to the relative plate motion that can be a few centimeters per year. Furthermore, the spatial extent of the signal extended thousands of kilometers along the plate boundaries.
"It is a common assumption that deeper subduction proceeds at a fairly constant speed in between large earthquakes," says Bedford. "Our study shows that this assumption is an oversimplification. In fact, its variability might be a key factor in understanding how the largest earthquakes nucleate."
With global satellite tracking now becoming better and better, and with accurate data available for the first time in decades, earthquake researchers have an ever-increasing ability to make such observations.
"We can now trace movements back decades," says Bedford. "In the next stage, we'd like to monitor the changes in near real time."
Not Suitable as an Early Warning System
Until now, seismologists have been more able to say where large earthquakes are likely to occur — less able to say when. By simply calculating the magnitude of the last large earthquake in a region and knowing the average relative plate velocity, one can estimate when that fault will be mature enough to sustain a repeat event, although there are great uncertainties in this approach. This is because sometimes a fault will rupture only over a smaller area (e.g. with a "large" magnitude 8 event) and other times it will rupture over many magnitude 8 regions all at once (e.g. in a "mega" magnitude 9 event).
Could an observed untypical plate movement therefore give us a better warning of an imminent earthquake? Not really.
"It would not be wise for a geophysicist to issue such a warning," is Bedford's sobering answer. "The observed signals of this study are not necessarily precursory movements of a major quake."
More research is necessary and as a matter of principle, people in known earthquake areas should not let their guard down.
"The general public should always be prepared," Bedford warns.
Reposted with permission from Deutsche Welle.
EcoWatch Daily Newsletter
A "trash tsunami" has washed ashore on the beaches of Honduras, endangering both wildlife and the local economy.
More long-finned pilot whales were found stranded today on beaches in Tasmania, Australia. About 500 whales have become stranded, including at least 380 that have died, the AP reported. It is the largest mass stranding in Australia's recorded history.
- Annual Whale Slaughter Still a Tradition on the Faroe Islands ... ›
- Hundreds of Pilot Whales Die in Devastating Mass Stranding in New ... ›
- Green Group Tests Facebook With Ad Claiming Conservatives Back ... ›
- Illegal Wildlife Trade Thrives on Facebook, Internet Forums ... ›
- Facebook Loophole Allows Climate Deniers to Spread Misinformation ›
- Facebook Hires Koch-Funded Climate Deniers for 'Fact-Checking ... ›
By Harry Kretchmer
By 2030, almost a third of all the energy consumed in the European Union must come from renewable sources, according to binding targets agreed in 2018. Sweden is helping lead the way.
Sweden is a world leader in renewable energy consumption. Swedish Institute/World Bank
Naturally Warm<p>54% of Sweden's power comes from renewables, and is helped by its geography. With plenty of moving water and 63% forest cover, it's no surprise the <a href="https://sweden.se/nature/energy-use-in-sweden/#" target="_blank">two largest renewable power sources</a> are hydropower and biomass. And that biomass is helping support a local energy boom.</p><p>Heating is a key use of energy in a cold country like Sweden. In recent decades, as fuel oil taxes have increased, the country's power companies have turned to renewables, like biomass, to fuel local 'district heating' plants.</p><p>In Sweden these trace their <a href="https://www.sciencedirect.com/science/article/pii/S0360544217304140#fig3" target="_blank">origins back to 1948</a>, when a power station's excess heat was first used to heat nearby buildings: steam is <a href="https://www.sciencedirect.com/topics/engineering/district-heating-system" target="_blank">forced along a network of pipes</a> to wherever it's needed. Today, there are around 500 district heating systems across the country, from major cities to small villages, providing heat to homes and businesses.</p><p>District heating used to be fueled mainly from the <a href="https://www.sciencedirect.com/science/article/pii/S0360544217304140" target="_blank">by-products of power plants</a>, waste-to-energy plants and industrial processes. These days, however, Sweden is bringing more renewable sources into the mix. And as a result of competition, this localized form of power is now the country's<a href="https://www.sciencedirect.com/science/article/pii/S0360544217304140#fig3" target="_blank" rel="noopener noreferrer"> home-heating market leader.</a></p>
Sweden is using smart grids to turn buildings into energy producers. Huang et al/Elsevier
Energy ‘Prosumers’<p>But Sweden doesn't stop at village-level heating solutions. Its new breed of energy-generation takes hyper-local to the next level.</p><p>One example is in the city of Ludivika where 1970s flats <a href="https://www.buildup.eu/sites/default/files/content/transforming-a-residential-building-cluster-into-electricity-prosumers-in-sweden.pdf" target="_blank">have recently been retrofitted with the latest smart energy technology</a>.</p><p>48 family apartments spread across 3 buildings have been given photovoltaic solar panels, thermal energy storage and heat pump systems. A micro energy grid connects it all, and helps charge electric cars overnight.</p><p>The result is a cluster of 'prosumer' buildings, producing rather than consuming enough power for 77% of residents' needs. With <a href="http://www.diva-portal.org/smash/get/diva2:1232060/FULLTEXT01.pdf" target="_blank" rel="noopener noreferrer">high levels of smart meter usage</a>, it's a model that looks set to spread across Sweden.</p>
<div id="d7bf9" class="rm-shortcode" data-rm-shortcode-id="8757b138d5570bec9d6aad18074a429a"><blockquote class="twitter-tweet twitter-custom-tweet" data-twitter-tweet-id="1273556364263071744" data-partner="rebelmouse"><div style="margin:1em 0">Read more about Western Harbour and book a visit: https://t.co/ujSmVs9rNK 🏡🌳🌊 https://t.co/C5PuPziqIM</div> — Smart City Sweden (@Smart City Sweden)<a href="https://twitter.com/SmartCitySweden/statuses/1273556364263071744">1592474473.0</a></blockquote></div>
Scaling Up<p>A recent development by E.ON in Hyllie, a district on the outskirts of Malmö, southern Sweden, <a href="https://www.eonenergy.com/blog/2019/February/sweden-smart-city" target="_blank">has scaled up the smart grid principle</a>. Energy generation comes from local wind, solar, biomass and waste sources.</p><p>Smart grids then balance the power, react to the weather, deploying extra power when it's colder or putting excess into battery storage when it's warm. The system is not only more efficient, but bills have fallen.</p><p>Smart energy developments like those in Hyllie, Ludivika, and renewable-driven district heating, offer a radical alternative to the centralized energy systems many countries rely on today.</p><p>The EU's leaders have a challenge: how to generate 32% of energy from renewables by 2030. Sweden offers a vision of how technology and local solutions can turn a goal into a reality.</p>
- Sweden to Become One of World's First Fossil Fuel-Free Nation s ... ›
- These Countries Are Leading the Transition to Sustainable Energy ... ›
- Sweden Shuts Down Its Last Coal Plant Two Years Early - EcoWatch ›
By Jessica Corbett
In another win for climate campaigners, leaders of 12 major cities around the world — collectively home to about 36 million people — committed Tuesday to divesting from fossil fuel companies and investing in a green, just recovery from the ongoing coronavirus pandemic.
- Oxford Endowment Ditches Fossil Fuels in 'Historic' Decision ... ›
- Fossil Fuel Divestment Debates on Campus Spotlight Societal Role ... ›
- London and New York Mayors Call on Other World Cities to Divest ... ›