Tag Archives: Japan

The 2016 Ecuador Earthquake

by Camilla Watson

An earthquake of magnitude 7.8 occurred in Ecuador on the 16th April this year. With the current death toll at 654 and another 58 still missing, this is one of the most devastating disasters South America has seen in modern times. Although the earthquake epicentre was in a relatively sparsely populated area, according to the US Geological Survey the focus was shallow at 19.2km (12 miles) and located 27km (17 miles) from Muisne off the west coast of northern Ecuador, meaning the effects were stronger than expected upon the Earth’s surface.

Ecuador_quake
Ground shaking from the magnitude 7.8 Ecuador earthquake. Source: USGS

The main initiator of earthquakes is tectonic plate movement. This particular earthquake was caused by a shallow thrust fault on or near the boundary between the Nazca and South American tectonic plates (USGS, 2016). In real terms, this means the Nazca plate is sliding beneath the South American plate, and the build-up of energy due to friction is realised in one sudden slip, causing the earthquake and its aftershocks (Wald, 2009).  Similar systems have caused some of the strongest earthquakes in the world, including the 1960 Chile earthquake of magnitude 9.5 – the largest ever recorded. Due to the presence of the subduction zone, this particular area within Ecuador is known to be prone to earthquakes, with many of the quakes occurring at 0-70km depths beneath the Earth’s surface. This often causes the consequences to be more devastating. The subduction system is also responsible for the formation of the Andes, the longest mountain chain in the world, and the high levels of volcanism within the area (USGS, 2016).

Scientists have been speculating as to whether the 2016 Ecuador earthquake was linked to the magnitude 7.0 Japan earthquake that occurred the day before, on the 15th April, with a shallow focus at 10km depth (Byrd, 2016). The idea behind this is something known as ‘remote triggering’, whereby a magnitude 6.5 earthquake in Japan would have caused slip along the boundaries of the tectonic plates on the other side of the Pacific Ocean, which triggered the tremors that made up the earthquake (Brown, 2016). However, this may also be chance due to both localities being situated on the Ring of Fire, an area known to be extremely tectonically active. Research so far shows no evidence for remotely triggered earthquakes to reach magnitudes above 5, making this particular situation between Ecuador and Japan either the first recorded case of its kind, or a coincidence. However, there has not yet been enough time for thorough research, but many earth scientists will now be focusing on the possibilities of using this information to help us to forecast and prepare for earthquakes in the future.

References:
[1] D. Byrd, (2016), Powerful earthquakes in Japan and Ecuador, EarthSky, [Online], Accessed 25/04/2016: http://earthsky.org/earth/powerful-earthquakes-japan-ecuador-april-2016
[2] E.K. Brown, (2016), Are the Japanese and Ecuador earthquakes related?, The Conversation, [Online], Accessed 25/04/2016: http://phys.org/news/2016-04-japanese-ecuador-earthquakes.html
[3] Fox News, (2016), Death toll in the powerful Ecuador Earthquake rises to 654, Fox News, [Online], Accessed 25/04/2016: http://www.foxnews.com/world/2016/04/24/death-toll-in-powerful-ecuador-earthquake-rises-to-654.html
[4] L. Wald (2009), The Science of Earthquakes, The Green Frog News, USGS, [Online], Accessed 25/04/2016: http://earthquake.usgs.gov/learn/kids/eqscience.php
[5] USGS, (2016), M7.8 – 27km SSE of Muisne, Ecaudor, United States Geological Survey (USGS), [Online], Accessed 25/04/2016: http://earthquake.usgs.gov/earthquakes/eventpage/us20005j32#general


Camilla_WatsonCamilla is a 3rd year undergraduate student in the School of Earth and Environment at the University of Leeds. She likes to combine her passion for travel with her love of geology. Check out her blog at: www.geologyandme.weebly.com

Earthquake liquefaction causes ground to open and close

The 2011 magnitude 9 earthquake in Japan was one of the largest earthquakes ever measured. Strong shaking and the consequent tsunami caused the death of nearly 18,000 people.

Strong vibrations in earthquakes can cause soil particles in the ground to jiggle about and lose contact with each other. If there is a lot of water within the ground the shaking causes soil to behave more like a liquid than a solid. This process is called liquefaction.

Footage taken by an American tourist shows dynamic movements of the ground during the Japan earthquake. The changing pressures caused by the soil movement can force water out of the ground and form moving cracks on the surface.

Note that this is not ground movements caused by the actual shaking in the earthquake, but by secondary soil movements.