Day 83 – Q 5. What are tsunamigenic forces? Which parts of the world are more vulnerable to tsunamis and why? Discuss.
5. What are tsunamigenic forces? Which parts of the world are more vulnerable to tsunamis and why? Discuss.
सुनामीकरक बल क्या हैं? दुनिया के कौन से हिस्से सुनामी की चपेट में हैं और क्यों? चर्चा करें।
Tsunamigenic is referring to those earthquakes, commonly along major subduction zone plate boundaries such as those bordering the Pacific Ocean, that can generate tsunamis. More broadly, tsunamigenic forces refer to any geological force capable of generating a tsunami in an ocean body.
- Most shallow large earthquakes in subduction zones cause tsunamis. An earthquake is tsunamigenic if it generates a tsunami, and it is “tsunami earthquake” if it generates a much larger tsunami than expected from its seismic waves.
- In some cases of subduction, part of the seafloor connected to the lighter plate may “snap up” suddenly due to pressure from the sinking plate. This results in an earthquake. The focus of the earthquake is the point within the Earth where the rupture first occurs, rocks break and the first seismic waves generate. The epicenter is the point on the seafloor (or other part of the Earth’s surface) directly above the focus.
- When this piece of the plate snaps up and sends tons of rock shooting upward with tremendous force, the energy of that force transfers to the water. The energy pushes the water upward above normal sea level. This is the birth of a tsunami. The earthquake that generated the Dec. 26, 2004, tsunami in the Indian Ocean had a magnitude of 9.1 — one of the biggest in recorded history.
- The occurrence of several mega-thrust tsunamigenic earthquakes in the last decade, including but not limited to the 2004 Sumatra-Andaman, the 2010 Maule, and 2011 Tohoku earthquakes, has been a dramatic reminder of the limitations in our capability of assessing earthquake and tsunami hazard and risk.
All low lying coastal areas can be struck by tsunamis, some of them can be very large; their height can be as great as 10 meters or more (30 meters in extreme cases), and they can move inland several hundred meters, depending on the slope of the ground. All oceanic regions of the world can experience tsunamis, but in the Pacific Ocean and its marginal seas, there is a much more frequent occurrence of large, destructive tsunamis because of the many large earthquakes along the margins of the Pacific Ocean.
These regions of the world are more vulnerable to tsunamis as they come under the regions of subduction zones of interacting plates in earth’s interior. For example, the Pacific ring of fire where most of the tsunami generating earthquakes occur underwater.
Short-term disaster response gives vital resources and hope to people living through disasters. But at the same time, longer-term solution like reducing the vulnerability of people in poverty by helping them create sustainable livelihoods to reduce their exposure to such risk should be focused upon to improve humanity’s fight against devastating natural calamities.