In this blogpost we explore top ten common misconceptions about earthquakes.
- 1. Earthquakes cause violent ruptures of the earth
- 2. It is better to run outside than staying inside during an earthquake
- 3. Earthquakes are predictable events
- 4. Earthquakes only happen during warm weather
- 5. The initial shaking is defining a marked ending to the earthquake
- 6. Earthquakes only happen in Japan and USA
- 7. Drills can negate earthquake damages
- 8. Building codes == safe buildings
- 9. The implications of earthquakes are local
- 10. Earthquakes are all the same
- Bonus: Earthquakes can change the length of a day
- References
Related read: Top 10 misconceptions about Tsunamis
1. Earthquakes cause violent ruptures of the earth
We all know the scenario from movies, the hero’s try and escape the rupture from the earth. The crack keeps running all the way up to the hero’s foot where it suddenly stops. This common misconception arises since when movies need to be more spectacular.
In fact, earthquakes tremble the earth for up to multiple minutes based on the severity of the earthquake. Earthquakes do not cause earth ruptures as illustrated by an AI below in meme 1.
Thus you shouldn’t be afraid that the earth will split underneath you during an earthquake.
2. It is better to run outside than staying inside during an earthquake
Often times people believe that running outside during an earthquake is safer than staying inside.
By going outside you risk being hit by falling debris, rubble and subduction zones while if you stay inside the building most likely will absorb the earthquake shaking.
It is therefore better to seek shelter inside sheltering yourself from above by hiding underneath tables, beds or sturdy furniture.
This way you are protected by the solidly built walls and ceilings of the building while simultaneously ensuring you are safe from falling books, chest of drawers, fridges, wardrobes and book shelf’s.
3. Earthquakes are predictable events
Unlike most other natural phenomena which we have extensively researched, the predictability of earthquakes still remain a resounding problem in science and engineering.
Top tier researchers still struggle with methodologies and theories to explain and provide early warning systems for earthquakes.
Typically sounding equipment is placed on locations around the globe, allowing the triangulation of epicenters to be calculated.
Related read: How do you calculate an earthquakes epicenter?
4. Earthquakes only happen during warm weather
In ancient greek, they believed that earthquakes were mystical events caused on warm sunny days where the earth opened up underneath their feet and closed again later on, see reference for more information.
Unlike the ancient Greeks, people today have a misconception that earthquakes happen during warm sunny weather.
Although this would be convenient allowing us to better estimate the eminent occurrence of an earthquake, sadly this isn’t the case.
Earthquakes are driven by deep earth dynamics governed by mass and heat transfers indifferent to top-earth weather phenomena.
Thus earthquakes can happen during sunny, rainy, snowy, foggy or stormy weather indifferent to other phenomena’s driving mechanisms.
Related read: Tsunamis the what, when and where
5. The initial shaking is defining a marked ending to the earthquake
A common misconception about earthquakes is that once the initial shaking stops the earthquake is over. This is however not the case. As aftershocks of earthquakes always accompanies the initial shaking and the higher on the Richter scale the earthquake is, the larger and long-lasting the aftershocks become.
Related read: Effective investment strategies for climate adaptations
This means that the danger after the initial shaking recedes unfortunately still resides. The dangerous aftershocks are critical to be vary off, since the initial shaking can loosen and damage buildings while the aftershocks cause weakened structures to collapse or loose debris to fall down on people below.
The Richter scale and aftershocks
The power of the aftershocks and the initial shaking follows a logarithmic scale naturally distributing with powers of 10 in magnitude. This scale, called the ‘Richter scale’ is widely used to describe the severity of experienced earthquakes, see Figure 1 as an example. This scale defines the magnitude of the initial shaking and also defines the aftershocks strengths.
In order to understand the distribution of aftershocks researchers have compared the temporal extent of the number of observed aftershocks with number of days since the main shaking event, see Figure 2. They have found that the distribution of aftershocks with number of shaking events follow an exponentially declining function with time since main shock.
6. Earthquakes only happen in Japan and USA
Another common misconception about Earthquakes is that they only happen at specific locations around the earth such as Japan and USA.
One of the driving mechanisms behind earthquakes is plate tectonics. Plate tectonics is theoretical framework that is the movement of continents and countries located on drifting (large timescale) plates at different parts of the world.
Plate tectonic
By indexing the world in tectonic sections each within its own plate see Figure 3. It is possible to explain most of the historic movements of continents throughout earth eras and develop theories for the occurrences of earthquakes whose likelihood depends on the locations of fault-lines of the different types such as subduction, lateral sliding and spreading.
The Western Mediterranean – a new example
As a newer example lets take a closer look at the interesting fault-lines which are the located at the Western Mediterranean towards the Gibraltar strait. This area is interesting because of the differences within the topographic and bathymetric features clearly shown in Figure 4.
Figure 4 and 5 include locations and markings of fault-lines together with recorded magnitude earthquakes. Arrows show the measured movement of the tectonic plates given as a yearly movement in mm’s. Corresponding to roughly 4.5 mm’s per year for the North African continental crust.
7. Drills can negate earthquake damages
To battle the damages of earthquakes we incorporate drills that explain to children that they should run for cover and hide underneath tables. This way of providing false hope to children can be dangerous if not correctly addressed.
Knowing when to run outside and when to seek cover inside is important as a means of preventing human injury during an earthquake. The damaging forces from earthquakes are not influenced by people running away from them.
In order to mitigate the damaging effects of earthquakes it is therefore necessary to continuously invest sturdier building materials, equipment and tuned mass dampers for high-risers. Such that buildings resistance towards the damaging shaking of earthquakes are continuously improving.
Preemptive investments are key to ensure that future disastrous events are accounted for and mitigated as much as possible.
Related read: Effective climate adaptation strategies
The drills are an important supplement which allow people to react quickly in the event of an earthquake. This must be accompanied by smart investment decisions enhancing the existing building mass for everyone benefit.
8. Building codes == safe buildings
Strict building codes lead to safer buildings. This is a common misconception present across the globe.
In fact, the foundation for safe buildings is strict building codes mixed with the efficient quality assurance. High-quality building work with proper quality control, safe building environments and senior-staff controlling junior is key.
The senior staff must check work carried out by junior laborer, allowing for the detection of faults and errors early on in the building process. The early detection of errors is critical for ensuring high-quality work and consequently safe buildings according to the strict building codes.
9. The implications of earthquakes are local
The effects of earthquakes can cause other dangerous events such as Tsunamis. Implications of earthquakes and the resulting consequences of their generated Tsunamis are dangerous and possibly globally covered.
The Tsunamis can spread from epicenters across the globe causing massive damages all because of earthquakes are displacing large amounts of water.
The damages on energy infrastructure such as nuclear powerplants can potentially damage the environment of the entire globe. These powerplants are vulnerable to earthquakes happening in the vicinity. History tells us that nuclear waste as a result of earthquake disasters can spread across the globe and pose a real threat for the environment and the people living in it.
10. Earthquakes are all the same
A common misconception about earthquakes is that all of them are the same in the fact that they are developing similarly across the globe regardless of the fault line types.
This is incorrect since earthquakes are dynamic phenomena whose development depend on the different instances of the boundary conditions as well as the soils initial state before the shaking starts.
The marginal effects of earthquakes are essentially changing with the initial state of the soil, plate tectonics and recent geological activity. These effects are difficult if not impossible to accurate describe throughout the three-dimensional medium.
Geophysical surveys make it easier to try and estimate tectonic plate composition. The survey depths of intrusion are however sufficiently deep to fully explain the plate tectonic behavior.
Bonus: Earthquakes can change the length of a day
In fact earthquakes are not only powerful destructive events, they can actually (in theory) change the length of a day on earth.
By releasing an increasing amount of energy through the shaking events, it is possible for the most powerful earthquakes to change earths rotation and thus the length of a day.
References
https://www.earthmagazine.org/article/earthquakes-shaped-ancient-greek-culture/
http://www.earthquakes.bgs.ac.uk/research/events/tohoku/honshuMarch2011Aftershocks.html
Gómez de la Peña, L., R. Ranero, C., Gràcia, E. et al. Evidence for a developing plate boundary in the western Mediterranean. Nat Commun 13, 4786 (2022). https://doi.org/10.1038/s41467-022-31895-z. Used under creative commons license 4: http://creativecommons.org/licenses/by/4.0/.