Indonesia’s Shallow Earthquake : Daily Current Affairs

Date: 25/11/2022

Relevance: GS-1: Important Geophysical Phenomena such as earthquakes, tsunamis, Volcanic activity, cyclones etc., geographical features and their location.

Relevance: GS-3: Disaster Management.

Key Phrases: Earthquake, Fault Lines, Mercalli scale, Richter scale, Ring of Fire, Proximity, Shallowness of the Earthquake, Focus and Epicenter, Body Waves, P-Wave, S-Wave, Surface Wave, NDMA Guidelines.

Context:

Recently, Indonesia's shallow quake with 5.6 magnitudes left more than 160 dead and hundreds injured as buildings crumbled and terrified residents ran for their lives on Indonesia’s main island of Java.

Key Highlights:

Indonesia is frequently struck by earthquakes, volcanic eruptions and tsunamis because of its location on the arc of volcanoes and fault lines in the Pacific Basin known as the “Ring of Fire.”
- A majority of the world’s earthquakes occur in this area.

Reasons for Deadly Earthquake:

Proximity to Fault Lines
- The area probably has the most inland faults compared to the other parts of Java.
Shallowness of the Earthquake
- According to The U.S. Geological Survey, the quake was of 5.6 magnitudes and struck at a depth of 10 kilometres (6.2 miles).
- Even though the earthquake was medium-sized, it was close to the surface.
  - So the energy was still large enough to cause significant shaking that led to the damage.
Inadequate Infrastructure
- Buildings not being constructed using earthquake-proof methods were factors in the devastation.

Frequent Earthquakes in Indonesia:

Many of Indonesia's earthquakes are minor and cause little to no damage. But there have also been deadly earthquakes:
- In February, a magnitude 6.2 earthquake killed at least 25 people and injured more than 460 in West Sumatra province.
- In January 2021, a magnitude 6.2 earthquake killed more than 100 people and injured nearly 6,500 in West Sulawesi province.
- A powerful Indian Ocean quake and tsunami in 2004 killed 230,000 people in a dozen countries, most of them in Indonesia.

Earthquake

About
- An earthquake is the shaking of the surface of the Earth.
- It results from the sudden release of energy in the earth‘s lithosphere that creates seismic waves.
- Earthquake is the form of energy of wave motion transmitted through the surface layer of the earth.
Cause
- According to the theory of plate tectonics, the Earth’s crust and upper mantle are made of large rigid plates that can move relative to one another.
- Slips on faults near the plate boundaries can result in earthquakes.
Focus and Epicenter
- The point inside the earth where the earthquake rupture starts are called the focus or hypocentre.
- The point directly above it on the surface of the earth is the epicentre.
Fault Lines
- A fault is a place with a long break in the rock that forms the surface of the earth. When an earthquake occurs on one of these faults, the rock on one side of the fault slips with respect to the other.
Measurement
- The earthquake events are scaled either according to the magnitude or intensity of the shock.
  - Richter scale
    - The magnitude scale is known as the Richter scale.
    - The magnitude relates to the energy released during the earthquake which is expressed in absolute numbers, 0-10.
  - Mercalli scale
    - The intensity scale or Mercalli scale takes into account the visible damage caused by the event.
    - The range of intensity scale is from 1-12.
Seismic Waves
- Seismic waves are waves of energy caused by the sudden breaking of rock within the earth.
- They are the energy that travels through the earth and is recorded on seismographs.
- The two main types of waves are body waves and surface waves.
  - Body Waves:These waves travel into the body of the earth.These waves are somewhat like sound waves.These are faster than surface waves.
    - P-waves
      - Move faster and are first to arrive at the surface.
      - Travel through gaseous, liquid, and solid materials.
      - High frequency and are the least destructive.
    - S-waves
      - Arrive at the surface with some lag.
      - Travel only through solid materials.
  - Surface Waves
    - When the body waves interact with surface rocks, a new set of waves is generated that are called surface waves.
    - These waves move along the earth's surface.
    - Surface waves are also transverse waves in which particle movement is perpendicular to the wave propagation.
    - They are similar to waves on the water's surface.
    - They are the last to report on seismographs.
    - These waves are more destructive.

NDMA Guidelines of 2007 on Earthquake Preparedness

According to the guidelines, six pillars of earthquake management are-
1. Earthquake-resistant construction of new structures.
2. Selective seismic strengthening and retrofitting of existing structures.
3. Regulation and enforcement.
4. Awareness and preparedness.
5. Capacity development.
6. Emergency response.

Way Forward

Effective Preparedness
- The only solution to minimize the loss of lives and properties is effective preparedness against the earthquake.
  - Countries like Japan have proved this, where earthquakes are a common phenomenon yet the losses are negligible.
People’s Participation
- People’s participation, cooperation and awareness are the keys to success.
NDMA Guidelines
- The NDMA guidelines on earthquakes must be implemented in letter and spirit.
Tax Incentives
- Providing tax incentives to people who build earthquake-resistant buildings.
Emergency Response Capability
- Strengthening of emergency response capability in earthquake-prone areas.

Conclusion:

Goal 11 of the UN Sustainable Development Goals aims to “make cities and human settlements inclusive, safe, resilient and sustainable.”Its targets include the promotion of resilience to disasters such as earthquakes.
- Therefore, We must move towards developing and adopting policies that promote seismic sustainability.

Source: The Hindu

Mains Question:

Why do the majority of earthquakes occur at the ring of fire? Also, discuss the consequences of the earthquake. (150 Words).