Bihar Board Class 10 · Social Science · Matric exam 2027
Chapter 3: Earthquake and Tsunami — notes
The chapter’s 6 parts in the book’s order — the first idea of each and the points Medha Ma’am writes on the board — and the summary at the end. The full lesson and a check question for each part are in the app.
1. What is Earthquake and Tsunami
Okay, so you live on the solid surface of the earth.
- • Earthquake: vibration focus on land surface
- • Tsunami: vibration focus on ocean floor
- • Inside earth, temperature > 1000° C
- • Tsunami creates horizontal motion in sea water
- • Example: 26th Dec 2004 Tsunami, Bay of Bengal, Indira Point lost
2. Measuring the Intensity: Richter Scale
Now you may wonder, how do we actually know how strong an earthquake or a Tsunami is?
- • Richter scale: measures intensity of earthquake/Tsunami
- • Logarithmic scale
- • 1 unit increase = 10 times more intensity
- • Weak rock regions affected more:
- • fold mountains, faulted areas, oceanic deeps, mid oceanic ridges
3. Earthquake Zones of India
Okay, so almost every part of India feels earthquake vibrations.
- • Zone 1: Southern plateau — negligible danger
- • Zone 2: Peninsular coastal areas — limited danger
- • Zone 3: Indo Gangetic plains, Rajasthan, north Gujarat — sometimes destructive
- • Zone 4: Shiwalik Himalaya, north WB, Assam, NE India, Andaman-Nicobar — greater danger
- • Zone 5: Kutch, J&K, HP, Kumaun, Sikkim, Darjeeling — most dangerous
4. Seismic Waves, Focus and Epicenter
Okay, so, when an earthquake happens, vibrations travel through the earth.
- • P waves: first to arrive
- • S waves: transverse, slower than P
- • L waves: originate on surface, slowest, most destructive
- • Focus: origin point beneath the surface
- • Epicenter: point on surface where waves first recorded
- • Pre and post vibrations: low intensity, felt only with instruments
5. Preventive Measures from Earthquake
Okay, so earthquake is a natural disaster.
- • 1. Forecast using seismograph; also animal behaviour (China)
- • 2. Earthquake resistant building construction
- • 3. Safety of life and property: special protection force
- • 4. Administrative alertness: declare expected earthquake area
- • 5. NGOs: training, rescue dogs (Norway), video cameras (Japan)
- • During earthquake: stand near wall, don't run
6. Preventive Measures from Tsunami
Tsunami currents rise up to several meters and strike the coast with such impact that they destroy fishing boats, motor boats, settlements, and even uproot coconut trees, giving tourists on the beach no time to escape.
- • Forecast: mid-sea station senses horizontal movement, warns coast
- • Fishermen: safer in deep mid sea than near coast
- • Concrete embankments reduce wave impact on coast
- • Mangrove bushes reduce pressure on embankments
- • Training coastal people: when to run to sea or land
Summary
Okay, so let's go back over everything this chapter gave you. Earthquake and Tsunami are natural disasters, and both are linked to the internal structure of the earth. An earthquake has its focus on land. A Tsunami has its focus on the ocean floor. Both are measured on the logarithmic Richter scale. Then you learned how India is divided into 5 earthquake zones, based on how often and how intensely they shake, from the almost safe Zone 1 to the highly dangerous Zone 5. After that came the seismic waves — P, S and L waves — along with Focus and Epicenter, and the pre and post vibrations that come with an earthquake. We also looked at preventive measures for earthquakes — forecasting, earthquake resistant construction, safety forces, administrative alertness, and the role of non-government organisations and community help. And finally, preventive measures for Tsunami — mid-sea forecasting stations, keeping fishermen safe in deep sea, concrete embankments, Mangrove bushes, and training coastal people for relief and resettlement. That's a lot of ground covered. Tell me — between earthquake and Tsunami, which one do you think gives people more warning time before it strikes?
AskMedha · Medha Ma’am — Bihar Board Class 10 Social Science, Chapter 3. Written from the textbook, checked twice.
Questions parents and students ask
- How do I get the "Earthquake and Tsunami" notes as a PDF?
- Press "Save as PDF" — the phone’s print sheet opens; choose "Save as PDF" there. The PDF holds the notes only.
- Where are these notes written from?
- From the chapter’s own textbook text, part by part, in the book’s own terms; a second, independent model then checked every part against the book. The full lesson, a check question for each part and the practice are in the AskMedha app.
The same preparation, with Medha Ma’am — on your phone
Every question of every chapter with its model answer, practice questions in the board’s own shapes, 60 minutes of class a day, written answers marked, a test every Sunday and a WhatsApp report to parents.
Medha Ma’am is an AI teacher, not a live tutor. Every answer is checked twice; a person takes responsibility.