Earthquake is measured by:

Options

A. Baufort scale
B. Decibels
C. Newton
D. Richter scale

Explanation

To answer the question "Earthquake is measured by:", follow these steps:

### Step 1: Identify the Options
The options given are:
1. Buford scale
2. Decibels
3. Newton
4. Richter scale

### Step 2: Understand the Measurement of Earthquakes
Earthquakes are measured based on their intensity and magnitude. The most commonly used scale for measuring the magnitude of earthquakes is the Richter scale.

### Step 3: Recall the Purpose of Each Option
- **Buford scale**: Not a recognized scale for measuring earthquakes.
- **Decibels**: A unit for measuring sound intensity, not applicable to earthquakes.
- **Newton**: A unit of force, not used for measuring earthquakes.
- **Richter scale**: Specifically designed to measure the magnitude of earthquakes.

### Step 4: Conclusion
Based on the understanding of the options, the correct answer is the **Richter scale**. It was invented by Charles F. Richter in 1935 and is used to quantify the size of earthquakes.

### Final Answer
Earthquake is measured by the **Richter scale**.

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