Innovative Earth Science Learning Experiences

By the end of this lesson, students will:

• Understand the basics of seismic activity and how earthquake waves propagate through the Earth.
• Learn how seismologists determine the location and magnitude of earthquakes using seismic data.
• Explore the technology behind seismic data processing and how it helps identify and interpret seismic waveforms.

• Ensure your Raspberry Shake is ready and connected to the internet (setup instructions
  available here ).
• Provide students access to laptops or tablets with internet connectivity.
• Print student reading materials (optional).

Preparation Tip: Educators should complete the Shake setup guide and review the Classroom Tips page before teaching with the Shake.

Begin the lesson by informing students that they will assume the role of seismologists. They will learn about triangulation and practice locating earthquakes, gaining insight into the physics behind earthquake waves and their propagation.

• Body Waves: Earthquake waves that travel through the Earth’s interior.
• Surface Waves: Earthquake waves that travel along the Earth’s surface.
• P-Waves: Primary (pressure) waves, which are the fastest traveling earthquake waves.
• S-Waves: Secondary (shear) waves, which are slower than P-waves.
• Triangulation: A method using data from three or more seismographs to identify earthquake epicenters by analyzing arrival times of P and S waves at various stations.
• Frequency: The rate at which waves repeat from peak to peak.

What Are Waves:

To interpret seismic data effectively, it is essential to understand the different types of waves involved. Waves are energy transfers through a medium, such as air or water, and in this context, they refer to seismic waves generated by earthquakes. All waves share key characteristics:

Wavelength: The distance between consecutive peaks in a wave.

Amplitude: The height of the wave from peak to trough.

Frequency: The number of wave cycles that occur in one second, measured in hertz (Hz).

Types of Seismic Waves:

When an earthquake occurs, releases energy in the form of seismic waves that travel outward from the epicenter. There are two primary categories of seismic waves: body waves and surface waves.

Body Waves: Body waves consist of P-waves and S-waves and travel through the Earth’s interior.

P-Waves (Primary Waves): P-waves, also known as compressional waves, are the fastest and first detected by seismographs as they push and pull material during propagation.

S-Waves (Secondary Waves): Also called shear waves are slower than P-waves and create side-to-side motion as they pass through materials.

Surface Waves: Travel along the Earth’s surface and arrive last. They move similarly to ocean waves and can cause the most destruction due to their amplitude and prolonged duration.

One of the most important tasks seismologists perform when a new earthquake is recorded is identifying its epicenter—the point on the Earth’s surface directly above where the earthquake originates.

To locate an earthquake’s epicenter, seismologists rely on a method called triangulation. By measuring the time difference between the arrival of P-waves and S-waves at three or more seismographs, they can calculate the distance from each station to the epicenter. The intersection of these distances pinpoints the earthquake’s location.

Educators and students can replicate this process using the Raspberry Shake’s EQ Locator web app, which simplifies the triangulation process by visualizing waveforms and calculating distances automatically.

Time: 20-25 Minutes — “Picking” P- and S-Waves

Demonstration:

• Show students how to use the EQ Locator web app.
• Use the tutorial video to guide the demonstration.

Student Activity:

• Have students navigate to the EQ Locator app and practice identifying P- and S-waves to triangulate earthquake epicenters.

Discussion:

• Ask students to reflect on their experiences. Was “picking” P- and S-waves intuitive or challenging? What was their success rate?
• Encourage students to share their thoughts on how seismologists use data to interpret seismic activity and identify earthquake locations.

Time: 5 minutes

Reflection:

Ask students to write a short reflection (2-5 sentences) about their experience using the EQ Locator. What did they find challenging? What did they learn?

Class Discussion:

Volunteers can share with the class one thing they found challenging, and why.

Utilize Raspberry Shake to explore core Computer Science principles and establish a foundation for future coding projects involving the Shake.

• Ensure that your Raspberry Shake is set up and connected to the internet.
• Install Node-RED on a computer and familiarize yourself with its functionalities (installation guide).
• Create a ShakeMeter in Node-RED by following this tutorial.
• Provide students with access to computers with internet connectivity.
• Pre-install Node-RED on student computers (optional, this can also be done during class).
• Print student reading materials (optional).

Preparation Tip: Educators should complete the Shake setup guide and review the Classroom Tips page before teaching with the Shake..

To capture students’ interest, display a live “Shakemeter” on your screen (instructions available here). Inform students that this lesson will delve into the exciting intersection of computer science and programming with the Shake!

• Computer: A device that accepts data as input, processes it using programs, and outputs the processed data.
• Input: Commands or signals received by a computer from external sources.
• Output: The signal sent from the computer to another device or displayed on a screen.
• Process: The execution of a computer program.
• Analog: Pertaining to continuous variations or transmissions of a signal.
• Digital: Relating to discrete measurements or approximations that can be stored by a computer.
• Network: A collection of interconnected computers for sharing resources.
• Internet: A global information system connected by unique addresses based on the Internet Protocol (IP).
• UDP (User Datagram Protocol): A protocol for sending data over a network.

Basics of Computer Science – with Raspberry Shake:

To effectively utilize Raspberry Shake, students must grasp fundamental concepts of computer science. This lesson will cover these basics, laying the groundwork for future community projects. Let’s begin by addressing the question: “What is a computer?”

For an engaging introduction, consider sharing this informative video from Code.org.

In summary, computers receive input, process and store information, and then provide output.

It is crucial to recognize that all data handled by computers is digital, represented internally as ones and zeros. This binary data is encoded and decoded for human readability. In contrast, analog data represents continuous information through variable physical quantities. Digital data approximates analog data through a process called sampling—similar to connecting points along a curve in a connect-the-dots activity. While digital signals may not perfectly align with analog signals, they serve as effective approximations.

Understanding these concepts is essential when exploring Raspberry Shake’s components. The Raspberry Pi acts as the main “computer,” while the geophone sensor and digitizer are integral parts of the Raspberry Shake board. The geophone responds to analog signals by converting ground movement into continuous voltage information. This voltage is sampled by the digitizer, which transforms it from analog to digital format—this quantification process is central to recording seismic data.

Students will apply these concepts in a coded program designed to process and display UDP data from the Raspberry Shake!

Time: 20+ minutes — Start with Node-RED Connectivity

(If less than 20 minutes remain, consider closing this lesson and completing this activity in the next class.)

Each student should access a laptop or Raspberry Pi to run a Node-RED server, working in pairs if desired. Follow this tutorial to get started.

Time: 5-10 minutes — Written Reflection

Students will write a brief reflection (3-5 sentences) on their learning experiences and insights gained during the lesson. Consider prompting them with questions such as:

• Did today’s lesson change your perspective on computer science? If so, how?
• Did it increase your curiosity about coding? Why?
• Were there aspects that were difficult to understand? If so, what made them challenging?

Raspberry Shake processes its own data and publishes it to its own public databases. However, it is also possible to configure the Shake to send a raw data stream from itself to any device your network can reach. Raspberry Shake uses User Datagram Protocol (UDP), a type of data transfer protocol, to send data to any list of IP addresses and ports that happen to be listening. Using this raw data stream you can create your own graphs, or set up alerts and triggers in Node-Red.

This means that your Shake could be physically located anywhere in a building (or using the proper networking setup, anywhere in the world) and you can still comfortably receive the data in Node-Red on your computer. Imagine the possibilities! An email alert being sent by your Raspberry Pi at home, because your Raspberry Shake at school detected some unusual vibrations… Or you could trigger a camera to snap and email you a picture whenever footsteps are detected in your room. The possibilities are endless!

Node-Red is a visual, flow based programming language powered behind the scenes by JavaScript. It is an excellent way to introduce students to programming concepts and basic programs, unlike text based languages such as Python and JavaScript. It utilizes basic input, output, and function nodes to create “flows”, which can then be executed as programs. It is similar to the popular educational programming language Scratch, but much more applicable in real world situations that incorporate hardware and wiring.

The most simple way to run a Node-Red program is using a Raspberry Pi. It is already installed on the Pi, so there are no extra downloads or terminal commands necessary to run the program. If a Raspberry Pi is not available, you can still run and use Node-Red on any laptop or desktop.

You can access the browser-based interface by entering “localhost:1880” into the browser that is connected to the device running Node-Red. You should arrive at the Node-Red work space.

When data is exchanged over the internet it is sent using a protocol, which is a way of organizing data so that both parties know what’s going on. Most of the time when you download a file or send an email it is sent using Transmission Control Protocol (TCP), which is rather strict.

UDP is much less strict, and is more like a one-way fire hose of data rather than an orderly sequence of letters with acknowledgements and replies. If UDP packets arrive out of order, have some missing, or even if the data inside is unreadable, there is no acknowledgement and no re-sending of lost or bad data.

Because it is very fast and requires no acknowledgments, UDP also has a feature called multicast. This allows a data stream to be sent to multiple destinations at the same time. Raspberry Shake makes this powerful feature easily accessible for users to configure and use.

To connect your Raspberry Shake to Node-Red:

1. Connect to your Raspberry Shake’s web front end (rs.local) and go to settings
2. From the Settings page, click on the UDP STREAMS tab
3. Enter the IP address of the “listening” computer that is running Node-Red, and the port (default 8888)

Important:

• Both devices must be on the same local network
• Remember to click both the “plus icon” button and the “Save” button when adding the UDP stream

After connecting the Shake to Node-Red, we can start to use Node-Red to process and visualize the seismic data that is being streamed through the UDP port. The first thing we will do with the data is create a “Shakemeter” – a program that takes the real-time seismic data and converts it into a live visual measurement of the absolute amplitude and velocity at which the ground is shaking.

Here’s the code for the Absolute Amplitude function:

acc = 0;
num = 0;
for(const p of msg.payload.packets)
{
 acc += Math.abs(p);
 num++;
}

acc /= num;

msg.payload = acc;
return msg;

To implement this:

1. Import the code block using the top right menu (Import -> Clipboard)
2. Add the Dashboard “Gauge” Node after the smooth node
3. Configure the Gauge node with a range from zero to at least 50000
4. Create a Dashboard group and tab
5. Deploy your flow

Access your dashboard at http://yourIPaddress:1880/ui

Now you can test your Shakemeter by creating vibrations and watching the gauge respond in real-time!

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