Basic Electronics for Beginners: IoT Based Multi Disaster Alert System

1. Introduction

In this final evolution of our safety series, we are building a "Global Alert" station. This system detects Earthquakes using an accelerometer, Tsunamis via rapid sea-level shifts, and continues to monitor Floods and Fire. With SD Card logging and ThingSpeak Cloud, this is a professional-grade project for any electronics enthusiast.

2. Components

Microcontroller: NodeMCU ESP8266.
Earthquake Sensor: MPU6050 (3-Axis Accelerometer).
Tsunami/Flood Sensor: HC-SR04 Ultrasonic Sensor (placed over water).
Fire Sensor: MQ-2 Smoke/Gas Sensor.
Data Storage: Micro SD Card Module + SD Card (FAT32).
Alert System: I2C LCD 16x2 and a High-Decibel 5V Buzzer.
Cloud: ThingSpeak IoT Platform.

3. Circuit and Connections

Pinout Diagram NodeMCU

MPU6050 Pinout Diagram

PIN-OUT Diagram LCD WITH I2C

Pinout Diagram SD Card Module

Pinout Diagram JSN SR04T Ultrasonic Sensor

Pinout Diagram of MQ-2 Sensor

Pinout Diagram of Buzzer

Component	Pin on Sensor	Pin on NodeMCU
MPU6050 (I2C)	SDA / SCL	D2 / D1
I2C LCD	SDA / SCL	D2 / D1 (Shared)
SD Card (SPI)	CS / MOSI / MISO / CLK	D8 / D7 / D6 / D5
JSN SR04T	Trig / Echo	D3 / D4
MQ-2 Sensor	Analog Out	A0
Buzzer	Positive (+)	RX (GPIO3)

4. Detailed Step-By-Step Circuit Working

Seismic Detection: The MPU6050 constantly tracks gravity on the X, Y, and Z axes. A sudden spike in these values indicates a tremor or earthquake.
Tsunami Logic: While a flood is a slow rise, a Tsunami is a massive, high-speed surge. The HC-SR04 detects if the water level changes by more than 20cm in less than 2 seconds.
Redundant Logging: The data is written to the SD Card every 5 seconds. If the earthquake knocks out the Wi-Fi, the history of the event is saved locally.
Cloud Reporting: ThingSpeak receives the "Vibration Level" and "Water Depth" to create a live disaster map.

5. Libraries to be Included

Adafruit_MPU6050.h (For earthquake sensing)
Adafruit_Sensor.h (Unified sensor driver)
ThingSpeak.h
SD.h & SPI.h
LiquidCrystal_I2C.h

6. Code

C++
#include <Adafruit_MPU6050.h>
#include <Adafruit_Sensor.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <ESP8266WiFi.h>
#include <ThingSpeak.h>
#include <SD.h>

Adafruit_MPU6050 mpu;
LiquidCrystal_I2C lcd(0x27, 16, 2);
WiFiClient client;

const int trig = D3; const int echo = D4;
const int buzzer = 3; // RX Pin
unsigned long myChannel = 1234567;
const char* myKey = "API_KEY_HERE";

void setup() {
  lcd.init(); lcd.backlight();
  mpu.begin();
  pinMode(trig, OUTPUT); pinMode(echo, INPUT);
  pinMode(buzzer, OUTPUT);
  WiFi.begin("SSID", "PASS");
  ThingSpeak.begin(client);
  SD.begin(D8);
}

void loop() {
  sensors_event_t a, g, temp;
  mpu.getEvent(&a, &g, &temp);

  digitalWrite(trig, LOW); delayMicroseconds(2);
  digitalWrite(trig, HIGH); delayMicroseconds(10);
  digitalWrite(trig, LOW);
  float dist = pulseIn(echo, HIGH) * 0.034 / 2;

  // Earthquake Detection (Threshold > 15m/s^2)
  bool earthquake = (abs(a.acceleration.x) > 15 || abs(a.acceleration.y) > 15);
  // Tsunami Detection (Rapid water rise)
  bool tsunami = (dist < 10); 

  if (earthquake || tsunami) {
    digitalWrite(buzzer, HIGH);
    lcd.clear(); lcd.print("QUAKE/TSUNAMI!");
    ThingSpeak.setField(1, 1); // Alert Status
  } else {
    digitalWrite(buzzer, LOW);
    lcd.setCursor(0,0); lcd.print("Stable Ground");
  }

  ThingSpeak.setField(2, a.acceleration.x);
  ThingSpeak.setField(3, dist);
  ThingSpeak.writeFields(myChannel, myKey);
  
  delay(15000); 
}

7. Detailed Step-By-Step Code Working

abs(a.acceleration.x): We use absolute values because an earthquake can shake the sensor in both positive and negative directions.
Tsunami Trigger: The code checks if the distance between the sensor and the water is critically low. In a real-world scenario, you would compare the current reading to a "rolling average" to detect a sudden surge.
Field Mapping: Field 1 acts as a "Digital Switch" (0 for safe, 1 for alert) so you can set up email notifications on ThingSpeak.

8. Tips

Mounting: The MPU6050 must be bolted to a solid surface (like a wall or heavy base). If it is loose on a breadboard, you will get "false earthquake" alarms.
I2C Conflict: Ensure your LCD and MPU6050 have different I2C addresses (usually 0x27 and 0x68).
Power: Use a high-quality 5V power supply; SD cards and Wi-Fi modules can draw up to 500mA during write cycles.

9. Uses

Coastal Safety: Monitoring tide levels for sudden Tsunami threats.
Structural Health: Placing sensors on bridges or buildings to detect vibration fatigue.
IoT Networking: Connecting multiple stations to a central ThingSpeak dashboard for a "Regional Alert" system.

10. Conclusion

This project represents the peak of beginner IoT electronics. By integrating seismic, aquatic, and atmospheric sensors into a single cloud-connected device, you have created a system that mirrors the technology used by global disaster response teams.