The National Ocean and Atmospheric Administration (NOAA) released an animation last year that displays every recorded earthquake between January 1, 2001, and December 31, 2015. Despite the fact that this video was released several months ago, it’s a remarkable way to visualize Earth’s plate boundaries and the dynamic changes in Earth’s crust.
Can you pick out the Pacific Ring of Fire, the Mid-Atlantic Ridge, the collision of India with Eurasia, the building of the Andes? So much information is packed into one animation it’s worth discussing what earthquakes tell us about global plate tectonics and mountain building.
The video is both color coded by earthquake depth and sized dependent on the magnitude. Hotter colors represent shallower earthquakes whereas cooler colors represent deeper earthquakes up to 800 km. The circles are sized based on magnitude but then shrink as to not obscure subsequent earthquakes. At the end of the video, there is a compilation of every earthquake in that 15-year time frame, earthquakes with magnitude larger than 6.5 and those with a magnitude larger than 8.
Some of the most notable earthquakes in this time period include the 9.1 magnitude earthquake in Sumatra in 2004, the 8.1 M in Samoa in 2009, the 8.8 M in Chile in 2010 and the 9.0 M off Japan in 2011. In the 15 year window, there were 20 earthquakes larger than 8.0 M and two larger than 9.0 M (see table below).
|Sumatra & Andaman Islands||9.1||December 26, 2004|
|East Coast Of Honshu||9.1||March 11, 2011|
|Offshore Of Central Chile||8.8||February 27, 2010|
|Northern Sumatra||8.6||March 28, 2005|
|West Coast Of Northern Sumatra||8.6||April 11, 2012|
|Coast Of Southern Peru||8.4||June 23, 2001|
|Southern Sumatra||8.4||September 12, 2007|
|Hokkaido||8.3||September 25, 2003|
|Kuril Islands||8.3||November 15, 2006|
|Sea Of Okhotsk||8.3||May 24, 2013|
|Central Chile||8.3||September 16, 2015|
|West Coast Of Northern Sumatra||8.2||April 11, 2012|
|Northern Chile||8.2||April 1, 2014|
|North Of Macquarie Island & South Of New Zealand||8.1||December 23, 2004|
|East Of Kuril Islands||8.1||January 13, 2007|
|Solomon Islands||8.1||April 1, 2007|
|Samoa Islands||8.1||September 29, 2009|
|Tonga||8.0||May 3, 2006|
|Coast Of Central Peru||8.0||August 15, 2007|
|West Of Lata||8.0||February 6, 2013|
Plate Boundaries & Earthquake Activity
If you look at a map of every earthquake in the past 15 years side by side with a map of plate tectonics you can immediately see the similarities. This is because most earthquakes on Earth are triggered by movement of plates, specifically at plate boundaries.
After watching the video you will notice that there is a circular ring of earthquakes along the edges of the Pacific Ocean. This is called the Pacific Ring of Fire and is due to the subsidence of the Pacific plate underneath continental plates to the East, North, and West.
You can pick out small earthquakes on the big island of Hawaii as the hot spot continues to erupt in the middle of the Pacific Ocean. Also, notice the increasing number of earthquakes in Oklahoma associated with oil and gas industry’s salt water injection wells.
You will notice that the largest earthquakes are typically associated with convergent plate boundaries like the Himalayas. Whereas earthquakes along strike-slip boundaries like the San Andreas fault in California or divergent plate boundaries are typically limited to earthquakes less than 8.0M.
There is an incredible amount of information displayed in this video, allowing you to further understand the geology of your home town, state, or country. Take some time to watch the video and post any questions you may have below.