Shindo Scale

Japan is a country located in one of the most seismically active regions in the world, known as the Pacific Ring of Fire. Consequently, it faces frequent earthquakes, some of which can be highly destructive. To measure the intensity of these earthquakes and their potential impact on structures and human life, Japan uses a unique seismic intensity scale known as the Shindo scale.

Understanding the Shindo Scale

The Shindo scale, also known as the Japan Meteorological Agency (JMA) Seismic Intensity Scale, is a measurement system used to assess the intensity of earthquakes specifically in Japan. Unlike the more commonly known Richter scale or moment magnitude scale (Mw) that measures earthquake magnitude, the Shindo scale focuses on the observed effects of an earthquake on structures and people in a particular area.

Working of the Shindo Scale

The Shindo scale ranges from 0 to 7, with 0 being the lowest level of intensity and 7 representing the highest. It is a subjective scale based on human observation, rather than instrumental readings. Trained personnel from the Japan Meteorological Agency assess the intensity of an earthquake at different locations using standardized guidelines. They take into account factors such as the shaking intensity, the damage caused to buildings, and how people perceive the quake’s effects.

Shindo Scale Intensity Levels and Effects

Here are the intensity levels of the Shindo scale along with their corresponding effects:

• Level 0 – Not felt: Earthquake not felt by most people.
• Level 1 – Weak: Felt by some individuals but not by others. Not capable of causing any damage.
• Level 2 – Weak: Felt indoors by some people, but most do not notice it. No damage.
• Level 3 – Weak: Felt by many indoors, few outdoors. No significant damage to buildings.
• Level 4 – Light: Felt by most people. Hanging objects may sway, and weak plaster may fall off walls.
• Level 5 – Moderate: Felt by everyone. Some poorly built structures may experience minor damage.
• Level 6 – Strong: Felt by all, even while driving. Some buildings may suffer partial collapse.
• Level 7 – Very Strong: Difficult to stand, significant damage to structures even if well-built.

Key Differences Between the Shindo Scale and Other Scales

The Shindo scale differs from other seismic scales in several key aspects:

• Focus on Local Effects: While the Richter scale and moment magnitude scale measure the energy release of an earthquake, the Shindo scale assesses the local impact on structures and humans, providing a more practical understanding of its effects on daily life.
• Subjective vs. Objective: The Shindo scale relies on human observation and reports, making it more subjective than scales based on instrumental data. However, this also allows for quicker assessments in the immediate aftermath of an earthquake.
• Customized for Japan: The Shindo scale is tailored to Japan’s unique building standards, infrastructure, and seismic vulnerability. This makes it more relevant and useful for assessing earthquake impacts within the country.

Real-Life Examples

Let’s take a look at a couple of real-life examples of earthquakes in Japan and their corresponding Shindo scale measurements:

• 2011 Tohoku Earthquake: The devastating earthquake that struck off the east coast of Japan on March 11, 2011, had a magnitude of approximately 9.0 on the moment magnitude scale. However, its impact on different regions in Japan varied on the Shindo scale. Tokyo experienced a Shindo level of 5- (moderate), while areas closer to the epicenter, such as Miyagi prefecture, reached Shindo 7 (very strong).
• 1995 Kobe Earthquake: This earthquake, also known as the Great Hanshin Earthquake, had a magnitude of 6.9. Kobe city, the worst affected area, experienced a Shindo level of 7 (very strong), resulting in significant destruction and loss of life.

Advantages and Limitations of the Shindo Scale

The Shindo scale offers several advantages, including:

• Localized Information: It provides detailed information about the effects of an earthquake in specific areas, helping authorities prioritize response efforts.
• Ease of Comprehension: The scale is easy for the general public to understand as it describes the impact on daily life and structures.
• Rapid Assessment: Since it relies on human observation, Shindo scale data can be quickly collected and reported, aiding in the immediate response to earthquake events.

However, there are also some limitations:

• Subjectivity: Being subjective, the Shindo scale may vary slightly depending on the judgment of the observers, leading to inconsistencies in assessments.
• Limited Applicability: The scale is designed for Japan’s unique conditions and may not be directly applicable in other countries.
• Lack of Fine Detail: The Shindo scale may not provide the fine detail necessary for engineering and structural analysis, which other scales like the moment magnitude scale can offer.

The following table illustrates the Shindo Scale.

The Shindo scale is a crucial tool in Japan’s efforts to assess and respond to earthquakes effectively. By focusing on local effects and the impact on structures and people, it provides a comprehensive understanding of an earthquake’s intensity.