Over 1,600 dead in Myanmar after earthquake levels buildings | DW News

Key Concepts

• Earthquake magnitude and depth
• Rupture distance
• Unreinforced masonry brick and old concrete structures
• Aftershocks and their risks
• Earthquake-resistant construction
• Seismic strengthening
• Soft soil amplification

Earthquake in Myanmar: Destruction and Impact

• Event Details: A 7.7 magnitude earthquake struck Myanmar around midday on Friday, with its epicenter near Mandalay. The earthquake was followed by several aftershocks.
• Casualties: The military-led government reports over 1,600 fatalities.
• Destructive Factors:
  • Magnitude and Depth: The earthquake's magnitude (M 7.7) was significant, and its shallow depth (10 km) caused intense energy transmission to the ground.
  • Rupture Distance: The rupture distance of 100-200 km affected approximately 13-14 million people.
• Building Vulnerability:
  • Building Types: 160,000 to 180,000 buildings were affected, primarily unreinforced masonry brick and old concrete structures, which are inherently dangerous in earthquakes.
  • Damage Assessment: Approximately 30% of buildings are either collapsed or heavily damaged, with an additional 30% (around 50,000 buildings) being lightly damaged.
  • Potential Fatalities: Estimated fatalities could range from 10,000 to 100,000.

Search and Rescue Challenges

• Ongoing Risks: The primary challenge is the risk of aftershocks in the coming weeks, months, and even up to a year, posing a threat to urban search and rescue teams.
• International Assistance: Kit Miyamoto will be assisting international teams in Myanmar.

Rebuilding Recommendations for Myanmar

• Material Usage: Continue using locally available materials like brick and concrete.
• Training: Focus on training masons, laborers, contractors, and engineers to use these materials correctly for earthquake-resistant construction.
• Key Quote: "It's key here is do don't change too much actually the using the brick or concrete is okay it just that the make sure the the training to the you know Masons and laborers and contractors and Engineers so they can use these materials the correct way to make the earthquake resistant."

Earthquake Impact in Thailand (Bangkok)

• Different Context: Thailand is a richer country, but earthquake preparedness has not been a priority.
• Lack of Tradition: There is no established tradition of earthquake engineering.
• Soft Soil Amplification: Bangkok, despite being far from the epicenter (1000 km), sits on soft soil, which amplifies ground shaking, particularly affecting high-rise buildings.
• Seismic Strengthening: Buildings in Bangkok need to be seismically strengthened.

Technical Terms and Concepts

• Magnitude (M): A numerical scale representing the energy released by an earthquake.
• Epicenter: The point on the Earth's surface directly above the focus (hypocenter) of an earthquake.
• Aftershocks: Smaller earthquakes that follow a larger earthquake in the same area.
• Rupture Distance: The length of the fault that breaks during an earthquake.
• Unreinforced Masonry (URM): Brick or concrete block construction without steel reinforcement.
• Seismic Strengthening: Retrofitting existing buildings to make them more resistant to earthquake forces.
• Soft Soil Amplification: The phenomenon where soft soil layers amplify ground shaking during an earthquake.

Conclusion

The earthquake in Myanmar highlights the vulnerability of structures built with unreinforced materials in seismically active regions. The focus should be on training local workers to build earthquake-resistant structures using available materials. In Thailand, particularly Bangkok, the risk of soft soil amplification necessitates seismic strengthening of existing buildings, even at a distance from earthquake epicenters. The key takeaway is that appropriate construction techniques and seismic retrofitting are crucial for mitigating earthquake damage, regardless of a country's economic status.