Visualizing the Power and Frequency of Earthquakes
The surface of our planet is in a constant state of creation and destruction as the plates of the Earth collide. It is this movement of the Earth’s crust that causes earthquakes, sending tremors throughout the world.
Today’s graphic is inspired by a classic USGS diagram that tracks the scale and frequency of earthquakes.
Earthquakes occur because the crust of the Earth is made up of several plates. The boundaries of these plates create faults that can run into one another.
Earthquakes describe both the mechanism that causes a sudden stress release along plate boundaries and also the ensuing ground shaking.
They occur when stress builds up along a tectonic fault. This stress causes the two surfaces of the fault, which had previously been stuck together due to friction, to suddenly move, or slide, releasing energy in the form of seismic waves.
Measuring an Earthquake’s Impact
There are three factors to assess the impact of Earthquakes – magnitude, energy, and intensity.
Magnitude is a number most commonly associated with the Richter scale, describing the size of an Earthquake on a scale from 0 to 10 – the latter of which is the maximum motion recorded by a seismograph. Each increase by one on the scale represents a tenfold increase in the amplitude. There are over a million tremors around the planet each year, but it’s not until an earthquake reaches a magnitude of 4 that humans can typically feel it.
Another way to measure the size of an earthquake is by how much energy it releases. The amount of energy radiated by an earthquake is a measure of the potential for damage to man-made structures.
An earthquake releases energy at various frequencies, and in order to calculate accurately, you have to include all frequencies of shaking for the entire event. Some research suggests technology could harness this energy for power generation.
Intensity describes the severity of an earthquake with a qualitative evaluation of its effects on the Earth’s surface and on the built environment. An earthquake may have a high magnitude but if a city or landscape experiences little damage, it can be said that the intensity is low. The Modified Mercalli Intensity Scale measures this intensity.
The World’s Largest Earthquakes by Magnitude
Prior to the development and use of seismographs, around 1900, scientists could only estimate magnitudes, based on historical reports of the extent and severity of damage.
|May 22, 1960||Valdivia, Chile||9.4-9.6|
|March 27, 1964||Prince William Sound, Alaska||9.2|
|Dec. 26, 2004||Indian Ocean, Sumatra, Indonesia||9.1|
|March 11, 2011||Pacific Ocean, Tohoku Region, Japan||9.1|
|July 8, 1730||Valparaiso, Chile||9.1-9.3 (est.)|
|Nov. 4, 1952||Kamchatka, Russia||9|
|Aug. 13, 1868||Arica, Chile||8.5-9.0 (est.)|
|January 26, 1700||Pacific Coast, Modern Day British Columbia||8.7-9.2 (est.)|
|April 2, 1762||Chittagong, Bangladesh||8.8 (est.)|
|Nov. 25, 1833||Sumatra Indonesia||8.8 (est.)|
Earthquakes are a fact of life on Earth and mark distinct moments in history. One would think given our knowledge of earthquakes, that humans would avoid these locations – however, the very faults of the Earth also create its greatest advantages.
Living with Your Faults
It’s extremely common to find human settlements along the fault lines where earthquakes occur most frequently. Some could say that this is because these decisions were made before a complete understanding of science enabled us to know the potential risks involved.
However, a recent scientific study reveals that there may be more to the pattern than previously thought. Tectonically active plates may have produced greater biodiversity, more food, and water for our human predecessors.
Certain landscape features formed by tectonic processes such as cliffs, river gorges, and sedimentary valleys create environments that support access to drinking water, shelter, and an abundant food supply.
This inherent problem reveals that humans are more connected to their environments than previously thought. It comes down to a question of how well humans can adapt their lifestyle and built environments to a dynamic planet.
Now let’s worry about the asteroids…
The Anthropocene: A New Epoch in the Earth’s History
We visualize Earth’s history through the geological timeline to reveal the planet’s many epochs, including the Anthropocene.
The Anthropocene: A New Epoch in the Earth’s History
Over the course of Earth’s history, there have been dramatic shifts in the landscape, climate, and biodiversity of the planet. And it is all archived underground.
Layers of the planet’s crust carry evidence of pivotal moments that changed the face of the Earth, such as the ice age and asteroid hits. And scientists have recently defined the next major epoch using this geological time scale—the Anthropocene.
In this infographic we dig deep into the Earth’s geological timeline to reveal the planet’s shift from one epoch to another, and the specific events that separate them.
Understanding the Geological Timeline
The Earth’s geological history is divided into many distinct units, from eons to ages. The time span of each varies, since they’re dependent on major events like new species introduction, as well as how they fit into their parent units.
|Geochronologic unit||Time span||Example|
|Eon||Several hundred million years to two billion years||Phanerozoic|
|Era||Tens to hundreds of millions of years||Cenozoic|
|Period||Millions of years to tens of millions of years||Quaternary|
|Epoch||Hundreds of thousands of years to tens of millions of years||Holocene|
|Age||Thousands of years to millions of years||Meghalayan|
Note: Subepochs (between epochs and ages) have also been ratified for use in 2022, but are not yet clearly defined.
If we were to cut a mountain in half, we could notice layers representing these changing spans of time, marked by differences in chemical composition and accumulated sediment.
Some boundaries are so distinct and so widespread in the geologic record that they are known as “golden spikes.” Golden spikes can be climatic, magnetic, biological, or isotopic (chemical).
Earth’s Geological Timeline Leading Up to the Anthropocene
The Earth has gone through many epochs leading up to the modern Anthropocene.
These include epochs like the Early Devonian, which saw the dawn of the first early shell organisms 400 million years ago, and the three Jurassic epochs, which saw dinosaurs become the dominant terrestrial vertebrates.
Over the last 11,700 years, we have been living in the Holocene epoch, a relatively stable period that enabled human civilization to flourish. But after millennia of human activity, this epoch is quickly making way for the Anthropocene.
|Epoch||Its start (MYA = Million Years Ago)|
|Anthropocene||70 Years Ago|
The Anthropocene is distinguished by a myriad of imprints on the Earth including the proliferation of plastic particles and a noticeable increase in carbon dioxide levels in sediments.
A New Chapter in Earth’s History
The clearest identified marker of this geological time shift, and the chosen golden spike for the Anthropocene, is radioactive plutonium from nuclear testing in the 1950s.
The best example has been found in the sediment of Crawford Lake in Ontario, Canada. The lake has two distinct layers of water that never intermix, causing falling sediments to settle in distinct layers at its bed over time.
While the International Commission on Stratigraphy announced the naming of the new epoch in July 2023, Crawford Lake is still in the process of getting approved as the site that marks the new epoch. If selected, our planet will officially enter the Crawfordian Age of the Anthropocene.
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