From plane waves to polarization: learn seismic beamforming
interactively
⚠ Work in Progress ⚠
The Beamforming Playground is under active development. Some apps,
features, and guided exercises are incomplete and contain errors.
Feedback, bug reports, and feature requests are welcome!
Open an issue
or email us.
Welcome to the Beamforming Playground!
What is this website?
This is an interactive learning tool for
seismic beamforming—a technique used by
seismologists to detect earthquakes and understand how seismic
waves propagate through the Earth. Think of it like a virtual
laboratory where you can experiment with arrays of seismic sensors
and see what happens.
No prior knowledge is required! You can start exploring
immediately, and each app guides you through specific concepts
step by step.
Why should I care about beamforming?
Beamforming is fundamental to modern seismology. Here's why it
matters:
Earthquake detection: It helps find small
earthquakes that would otherwise be lost in background noise
Determining earthquake location: It tells us
both where an earthquake happened and how the
ground moved
Understanding Earth's interior: By analyzing
how waves travel through the Earth, we can map its internal
structure
Real-world applications: The same principles
apply to radar, sonar, wireless communications, and even medical
imaging
What is Beamforming, exactly?
Imagine standing in a field with your eyes closed, hearing a bird
chirp. With one ear, you know something is making a
sound. With both ears, you can tell which direction the
sound is coming from—because sound reaches your ears at slightly
different times.
Beamforming does the same thing, but with seismic stations
instead of ears.
By combining signals from multiple stations spread across tens or
hundreds of kilometers, we can:
Enhance weak signals (like distant earthquakes)
Determine the direction waves are coming from
Measure how fast waves are traveling (their velocity)
Separate different types of waves arriving at the same time
The mathematical technique is called "beamforming" because we can
mentally "point" our array in different directions—like steering a
beam of light—to see where the strongest signal comes from.
What's the difference between seismology and other beamforming?
You might be familiar with beamforming from other fields
(acoustics, antenna arrays, ultrasound). Seismic beamforming has
some unique twists:
2D arrays: Most seismic arrays are spread
across Earth's surface (2D), not in a line (1D)
Slowness, not angle: We measure wave speed as
"slowness" (inverse velocity) and steer in both azimuth and
slowness
Plane waves from far away: For distant
earthquakes, we assume flat wavefronts; for nearby sources, we
need curved wavefronts (Matched Field Processing)
This website lets you explore all these concepts interactively,
starting from the basics and progressing to more advanced topics.
How do I use this website?
The simplest approach: Just start with the first
app (Plane Waves), and follow your curiosity! Each app has a
"Guided Exercise" in the ☰ menu that walks you through specific
tasks.
What you'll do in each app:
Build arrays by clicking on the map, or choose
real arrays like Gräfenberg (Germany) or NORSAR (Norway)
Control wavefields using sliders for direction,
velocity, and frequency
Steer the beam by clicking in the array
response plot—watch the beam trace change as you find the
maximum
Follow guided exercises via the ☰ menu for
structured step-by-step learning
No installation needed. Everything runs in your browser. Best
experienced on a desktop or laptop with a mouse.
Which app should I start with?
If you're new to beamforming: Start with
Plane Waves—it teaches the fundamentals: array response
patterns, side lobes, resolution, and how to steer the beam.
If you want to explore further: The apps are
organized into "Basics" (for beginners) and "Advanced Concepts"
(for those with some experience). You can jump around based on
your interests!
Broadband Signals: Why wider frequency bands
give cleaner beams
Noisy Signals: How beamforming improves
signal-to-noise ratio
Multiple Sources: When can we separate two
simultaneous arrivals?
Matched Field Processing: Handling curved
wavefronts from nearby sources
Wave Types: Working with real earthquake wave
types (P, S, Rayleigh)
3-Component Beamforming: Using multiple sensor
orientations for polarization analysis
How much math do I need to know?
Short answer: None! These apps are designed to
build intuition first, without equations. You'll learn by
doing—clicking, sliding, observing, and experimenting.
Longer answer: The underlying mathematics
involves Fourier transforms, complex numbers, and wave propagation
physics. But you don't need to understand the math to grasp the
concepts. If you're curious, the code is all here for you
to explore—it's written in plain JavaScript with no external
dependencies.
I'm a teacher/instructor. How can I use this?
These apps work great for:
Live demonstrations in lectures—project the
screen and let students guide you
Labs or problem sets—have students complete the
guided exercises
Self-paced learning—assign specific apps as
homework
Exploration—let curious students discover
concepts on their own
Each app includes guided exercises that work well as structured
activities. The apps complement (rather than replace) textbooks
and lectures by making abstract concepts tangible.