Almost 800 minor earthquakes registered in São Miguel since 4th of June.
Fun Fact: Earthquake Basics Explained
Over the past few days, the island of São Miguel in the Azores has been experiencing a seismic crisis, with approximately 800 low-magnitude earthquakes recorded since June 4th. Here's a quick rundown of how we classify these quakes to better understand their impact.
Earthquake Classification: A Comprehensive Overview
When it comes to earthquakes, we typically measure their size and impact using two scales: the Richter Scale and the Modified Mercalli Scale. Let's dive into each:
1. The Richter Scale: Measuring Earthquake Size
Invented by Charles F. Richter in 1935, this logarithmic scale helps quantify the amount of energy released by a seismic event. The scale normally ranges from 1 to 10.
|Magnitude Range|Category|Typical Effects|Approximate Yearly Frequency||-|-|-|-||Less than 1.0 to 2.9|Micro|Not felt by people, only registered instrumentally|More than 100,000||3.0–3.9|Minor|Felt by many people but no damage|12,000–100,000||4.0–4.9|Light|Felt by all; minor breakage of objects|2,000–12,000|
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The most significant recorded tremors in the Azores, on June 15th (magnitude 3.3) and June 16th (magnitude 3.7), fall within the "Light" category, suggesting no structural damage.
2. The Modified Mercalli Scale: Measuring Earthquake Impact
Unlike the Richter Scale, the Modified Mercalli Scale measures the earthquake's perceived intensity based on the effects it has on people and structures, rather than its magnitude. The scale ranges from I (Not felt) to XII (Total destruction and ground changes).
|Intensity (MMI)|Description|Effects||-|-|-||I (Not felt)|Not felt except by a very few under especially favorable conditions|No damage||III (Weak)|Felt indoors, vibrations similar to a heavy truck passing by|No damage||IV (Light)|Felt outdoors, windows, dishes, doors rattle; cars rock|No structural damage|
For instance, with an intensity of III, the tremors in São Miguel were relatively weak and were only felt indoors, causing suspended objects to sway like during the passage of a heavy vehicle. Meanwhile, an intensity of IV implies that suspended objects sway, cars rock, and doors and shutters tremble, but no structural damage is expected.
Sources:
[1] The USGS Richter Scale (2017). Retrieved from https://www.usgs.gov/faqs/what-is-richter-scale-and-how-is-it-used-measure-earthquakes-and-volcanoes?qt-news_science_products=0#qt-news_science_products
[2] The EMSC Intensity scale (2021). Retrieved from https://www.emsc.eu/en/education/what-is-the-mercalli-scale
[3] Mercalli, G. (1902). Scale for the measurement of the intensity of the earthquake shaking (Mercalli’s scale). Earthquake Spectra, 3(1), 1–5. doi:10.1193/1.1743452
Enjoyed this quick lesson? Don't worry; we'll keep you updated on the situation in the Azores! Stay tuned for more fun facts and earthquake insights. 🙌🏽💥🗻Curveball: What is the primary difference between the Richter Scale and Modified Mercalli Scale?
A. Richter measures the energy released by an earthquake, while the Modified Mercalli Scale measures the effects on people and structures. B. The Richter Scale ranks earthquakes based on their destructive power, whereas the Modified Mercalli Scale quantifies the earthquake size. C. Both the Richter Scale and Modified Mercalli Scale measure the same aspects of earthquakes. D. The Richter Scale is less accurate than the Modified Mercalli Scale. E. The Richter Scale is used more in the United States, while the Modified Mercalli Scale is more popular in Europe. Correct Answer: A. Richter measures the energy released by an earthquake, while the Modified Mercalli Scale measures the effects on people and structures.
Though the earthquakes in São Miguel are classified as "Light" on the Richter Scale, suggesting no structural damage, they have still been felt indoors, reminiscent of a heavy truck passing by, as indicated by an intensity of III on the Modified Mercalli Scale. Moreover, understanding the environmental implications of seismic activities in the Azores, this region can also be considered a subject of interest in the field of environmental-science, particularly concerning the weather patterns that might be affected by these earthquakes.
