Richter Amplitude
Lesson notes
Overview
Ground motion amplitude grows tenfold per magnitude unit. This topic is rated beginner and is number 59 of 98 in Earth & Space. Core ideas and first intuitions. No prior knowledge needed.
What you are seeing
The panel above shows a graph of the function. Each slider changes one parameter, so you can see exactly how the curve bends, shifts or stretches. The animation is drawn live from the model, so everything you see responds to the sliders. Press Space to pause, use Restart to replay from the start, and change the speed to slow down quick events.
In depth
On the Richter scale each increase of one magnitude unit corresponds to a tenfold increase in the amplitude of the ground motion recorded on a seismograph, A ∝ 10^M, though the energy increases by about 32 times. Charles Richter devised it in 1935 for Californian earthquakes. A magnitude 6 quake shakes the ground ten times more than a 5, and 100 times more than a 4. The scale has no upper limit, but is not used for the very largest quakes.
Reading the relationship
The expression "A ∝ 10^M" is a compact summary of the idea. It uses the symbols A, M; name what each one stands for before you start. Notice that it contains a proportionality, so the two sides rise and fall together. Then use the sliders to see how changing one quantity changes the others.
A guided exploration
1. Set every slider to its middle value and note the shape of the curve. 2. Move one slider at a time and describe whether the curve shifts, stretches or turns. 3. Find the value where the behaviour changes sharply, then connect it to the formula.
Try this
Start by only moving one slider at a time. Say aloud what you expect, then check.
Common pitfalls
Earth and space systems work on very different scales of time and distance. Check which scale a number refers to before comparing it with another.
How it connects
It builds on “Earthquake Magnitude and Energy”, the topic before it in Earth & Space. Once you are comfortable, continue with “P-Wave and S-Wave Travel Times”.
Why it matters
Earth and space science helps us understand our planet, its climate and the wider universe.
Where you might use it
- Revising “Richter Amplitude” before a class, exam or certification
- Forecasting weather and understanding climate records and their uncertainty
- Planning for earthquakes, floods and other natural hazards in cities
- Interpreting satellite images, space missions and the age of rocks and stars
Frequently asked questions
What is Richter Amplitude?
Ground motion amplitude grows tenfold per magnitude unit. It is a beginner topic in Earth & Space.
How do I use the Richter Amplitude simulation?
The panel at the top shows a graph of the function. Each slider changes one parameter, so you can see exactly how the curve bends, shifts or stretches. Move the sliders one at a time, then press Space to pause the animation and look closer.
What does the formula mean?
The expression A ∝ 10^M packs the idea into symbols. Name each symbol first, then change one quantity with the sliders and see which others respond.
Who is this topic for?
Core ideas and first intuitions. No prior knowledge needed. If the quiz feels hard, reread the lesson notes and try the previous topic first.
What should I learn before this?
Start with “Earthquake Magnitude and Energy”, the previous topic in Earth & Space. Each topic in a subject builds on the ones before it.
How do I track my progress?
Press “Mark as learned” on this page. Progress is stored only in this browser and is never sent anywhere. The Browse page can show topics you have learned or still need to learn.