ESP32 Earthquake Detection System

by drahul1103 in Circuits > Arduino

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ESP32 Earthquake Detection System

earthquake.png

This is an ESP32-based earthquake early warning system that detects ground shaking using an accelerometer and alerts you with LED and buzzer warnings at two different sensitivity levels.

The project uses an MPU6050 accelerometer to monitor vibration on all three axes. A digital filter removes gravity noise so we can detect actual shaking. When acceleration crosses a low threshold, a blinking LED activates as an early warning. If shaking gets stronger and crosses a high threshold, a passive buzzer kicks in with a sweeping alarm tone. A backup KY-002 vibration switch provides secondary confirmation of shaking.

This teaches I2C sensor communication, digital filtering, and two-stage alert logic — the same principles used in real earthquake early warning systems.

Supplies

  1. ESP32 development board (with USB cable)
  2. MPU6050 accelerometer module (I2C sensor)
  3. Passive buzzer module (PWM-driven, not active buzzer)
  4. LED (any color)
  5. 220Ω current-limiting resistor
  6. Breadboard and jumper wires
  7. Arduino IDE with ESP32 board support

Wire All Sensors and Outputs to ESP32

MPU6050 accelerometer (I2C):

  1. VCC → ESP32 3V3
  2. GND → ESP32 GND
  3. SDA → ESP32 GPIO21
  4. SCL → ESP32 GPIO22

LED (visual warning):

  1. Positive leg → 220Ω resistor → ESP32 GPIO2
  2. Negative leg → ESP32 GND

Passive Buzzer (audio alarm):

  1. Signal → ESP32 GPIO5
  2. VCC → ESP32 3V3
  3. GND → ESP32 GND

Critical notes: SDA/SCL on the MPU6050 must not be swapped. GPIO5 must be used for the buzzer (it supports PWM). The LED's longer leg is positive and goes toward GPIO2 through the resistor. Double-check all connections before uploading code.

Install Library and Upload Code

First, install the MPU6050 library: In Arduino IDE, go Sketch → Include Library → Manage Libraries, search for MPU6050, and install the version by elektronn.

Then paste this code into a new Arduino sketch and upload it to your ESP32:

#include <MPU6050.h>
#include <Wire.h>

MPU6050 mpu;
const int LED_PIN = 2, BUZZER_PIN = 5, VIBRATION_SWITCH_PIN = 4;
const float LOW_THRESHOLD = 15.0, HIGH_THRESHOLD = 25.0;
float accel_x_filtered = 0, accel_y_filtered = 0, accel_z_filtered = 0;
const float ALPHA = 0.2;
bool led_blinking = false, buzzer_active = false;
unsigned long last_led_toggle = 0, last_check = 0;

void setup() {
Serial.begin(115200);
Wire.begin(21, 22);
pinMode(LED_PIN, OUTPUT);
pinMode(BUZZER_PIN, OUTPUT);
pinMode(VIBRATION_SWITCH_PIN, INPUT);
digitalWrite(LED_PIN, LOW);
digitalWrite(BUZZER_PIN, LOW);
if (!mpu.begin(MPU6050_SCALE_2000DPS, MPU6050_RANGE_16G)) {
Serial.println("MPU6050 not found!");
while (1);
}
Serial.println("MPU6050 initialized");
}

void loop() {
unsigned long now = millis();
Vector accel = mpu.readRawAccel();
accel_x_filtered = ALPHA * (accel_x_filtered + accel.XAxis);
accel_y_filtered = ALPHA * (accel_y_filtered + accel.YAxis);
accel_z_filtered = ALPHA * (accel_z_filtered + accel.ZAxis - 9.81);
float magnitude = sqrt(accel_x_filtered*accel_x_filtered +
accel_y_filtered*accel_y_filtered +
accel_z_filtered*accel_z_filtered);
bool vibration_detected = (digitalRead(VIBRATION_SWITCH_PIN) == LOW);
if (magnitude >= HIGH_THRESHOLD || vibration_detected) {
led_blinking = true;
buzzer_active = true;
}
else if (magnitude >= LOW_THRESHOLD) {
led_blinking = true;
buzzer_active = false;
}
else {
led_blinking = false;
buzzer_active = false;
}
if (led_blinking) {
if (now - last_led_toggle > 500) {
digitalWrite(LED_PIN, !digitalRead(LED_PIN));
last_led_toggle = now;
}
} else {
digitalWrite(LED_PIN, LOW);
}
if (buzzer_active) {
static unsigned long buzz_start = 0;
if (buzz_start == 0) buzz_start = now;
unsigned long buzz_age = (now - buzz_start) % 1000;
int freq = 800 + (buzz_age / 2);
if (buzz_age > 500) freq = 1300 - ((buzz_age - 500) / 2);
tone(BUZZER_PIN, freq, 10);
} else {
noTone(BUZZER_PIN);
}
if (now - last_check > 200) {
Serial.print("Accel: ");
Serial.print(magnitude, 2);
Serial.print(" m/s^2 | LED: ");
Serial.print(led_blinking ? "ON" : "OFF");
Serial.print(" | Buzzer: ");
Serial.println(buzzer_active ? "ON" : "OFF");
last_check = now;
}
}



Connect your ESP32 via USB, select Board: ESP32 Dev Module and the correct COM port, then click upload. Wait for "Done uploading" message.

Test the System

Once uploaded, open Arduino IDE's Serial Monitor (Tools → Serial Monitor, set to 115200 baud). You'll see real-time acceleration readings.

Gently tap or shake the breadboard near the ESP32:

  1. Light shaking (around 15 m/s²) → LED blinks
  2. Harder shaking (around 25 m/s²) → LED blinks + Buzzer alarm sounds with rising/falling tone
  3. Stop shaking → Both turn off within a second

Watch the Serial Monitor to see exact acceleration values. If the system doesn't respond, check that all wires are firmly seated in the breadboard and that GPIO pins match the code exactly.

Calibrate Thresholds

The default thresholds (15 m/s² for LED, 25 m/s² for buzzer) are starting points. Your setup may need different values depending on table mass and sensor placement.

While watching Serial Monitor output:

  1. Note the acceleration value for gentle shaking you want to trigger the LED
  2. Note the acceleration value for strong shaking you want to trigger the buzzer
  3. Set LOW_THRESHOLD to roughly 80% of your gentle value
  4. Set HIGH_THRESHOLD to roughly 80% of your strong value
  5. Re-upload and test again

You can also adjust the ALPHA in the filter value (currently 0.2): lower values (0.1) give smoother response but slower detection, higher values (0.3) give faster but noisier response.

How It Works and Next Steps

earthquake detection esp32 project

The System Logic: The MPU6050 reads acceleration hundreds of times per second. A high-pass filter (ALPHA coefficient) removes constant gravity, leaving only actual movement. When acceleration magnitude exceeds LOW_THRESHOLD, the LED blinks as a warning. If it exceeds HIGH_THRESHOLD or the vibration switch triggers, the buzzer sounds with a sweeping alarm tone. Both stay active until shaking stops.

Next Steps: You can expand this project by adding WiFi to send alerts to your phone, logging acceleration data to an SD card for analysis, or adding an OLED display to show real-time values. This same logic is used in actual seismic monitoring stations around the world.