Download to read offline
![MW - Seismic Moment magnitude
MW= log10A + 1.66 log10 Δ +2.0
A = Maximum ground displacement in micrometers
Δ= Distance of seismograph from the epicenter, in degrees.
ML - Local (Richter) magnitude
ML= log10A(mm) +3 log10[8Δt (sec)]-2.93
Here A is the amplitude, in millimeters
The S-P time, in seconds, makes Δt.
mb- Body wave magnitude
mb = log10A – log10T +0.01Δ + 5.9
A = Amplitude of P-waves in micrometers
T = period of P-wave
Δ = Distance of seismograph from the epicenter, in degrees.
MW - Seismic Moment magnitude
Moment Magnitude, Mw = 2/3 [log10M0(dyne-cm) –16]
Moment Magnitude, Mw = - 6.0 + 0.67 log10M0(N.m)
M0= DAμ
where D is the average fault displacement in m,
A is the total area of the fault surface in m2, and
μ is the shear modulus of material along the fault plane in N/m2 (=
3x1010 N/m2
for surface crust and 7x1012 N/m2 for mantle)
M0 is measured (Note: 1 dyne-cm = 1 × 10–7 newton-meter)
PAVAN KUMAR MEENA 34](https://image.slidesharecdn.com/earthquakeengineeringandseismology-210527084808/75/Basic-Introduction-to-Earthquake-engineering-and-seismology-34-2048.jpg)
More Related Content
Similar to Basic Introduction to Earthquake engineering and seismology
Basic Introduction to Earthquake engineering and seismology
- 1.
- 2. What is Earthquake AnEarthquake is the result of a sudden release of energy in the Earth’s crust that creates seismic waves. Or An Earthquake is the vibration of Earth produced by the rapid release of accumulated energy in elastically strained rocks. Fault: A fracture in the rocks that make up the Earth’s crust Epicenter: The point at the surface of the Earth above the focus Plates: Massive rocks that make up the outer layer of the Earth’s surface and whose movement along faults triggers earthquakes Seismic waves: Waves that transmit the energy released by an earthquake Focus (Hypocenter): The point within the Earth where an earthquake rupture starts PAVAN KUMAR MEENA 2
- 3.
- 4. A number ofsmaller size earthquake take place before and after a big earthquake. Foreshocks : Those occurring before the big one are called foreshocks. Aftershocks : Smaller size earthquakes occurring after the main shocks are called aftershocks. PAVAN KUMAR MEENA 4
- 5. SEISMIC WAVES PAVAN KUMARMEENA 5
- 6. Body Wave: pwave and S wave •Primary waves are the fastest body waves (twice the speed of s-waves) and are the first to reach during an earthquake. S waves can not pass through liquid. PAVAN KUMAR MEENA 6
- 7. Surface Wave: Rayleighwaves and Love waves All surface waves travel slower than body waves and Rayleigh waves are slower than Love waves. PAVAN KUMAR MEENA 7
- 8. Shadow zone orno light/wave area PAVAN KUMAR MEENA 8
- 9.
- 10. SEISMOGRAPH • The energyreleased during the earthquake travels as waves. • Device used to measure an earthquake is called ‘seismograph’. The seismograph has three main devices, the Richter Magnitude Scale, the Modified Mercalli Intensity Scale, and the Moment Magnitude (MW) Scale. PAVAN KUMAR MEENA 10
- 11.
- 12. Principal Types ofEarthquake Damages Structural Liquefaction Landslide Tsunamis PAVAN KUMAR MEENA 12
- 13.
- 14.
- 15.
- 16. Strongest and deadliestEarthquakes in World History PAVAN KUMAR MEENA 16
- 17.
- 18. List of CostliestEarthquakes of Century PAVAN KUMAR MEENA 18
- 19.
- 20. World Tectonic Plates PAVANKUMAR MEENA 20
- 21. Continental drift Theory thatcontinents and plates move on surface of the earth proposed by Alfred Wegener in 1915. PAVAN KUMAR MEENA 21
- 22.
- 23.
- 24. Seismology Seismology is thebranch of Geophysics concerned with the study and analysis of Earthquakes and the science of energy propagation through the Earth’s crust. The first such earthquake measuring instrument called Di-Dong-Di was invented by Cheng Heng (132 A.D.). Device used to measure an earthquake is called ‘seismograph’. The seismograph has three main devices, the Richter Magnitude Scale, the Modified Mercalli Intensity Scale, and the Moment Magnitude Scale. PAVAN KUMAR MEENA 24
- 25.
- 26.
- 27.
- 28. Seismographic stations aroundthe world function together to: • Determine the location of earthquake • Determine the strength of the earthquake Earthquakes usually occur at some depth below the ground surface. Earthquake are described as: – Shallow: less than 70 km depth – Intermediate: 70 - 300 km depth – Deep: 300 - 700 km depth 90% of earthquake focus are less than 100 km deep Large earthquakes are mostly at < 60 km depth No earthquakes occur deeper than 700 km PAVAN KUMAR MEENA 28
- 29. Magnitude and Intensityof an Earthquake Intensity • How strong earthquake feels to observer. • Qualitative assessment of the kinds of damage done by an earthquake. • Depends on distance to earthquake & strength of earthquake. • Determined from the intensity of shaking and damage from the earthquake. • Expressed using modified Mercalli scale. Magnitude • Related to energy release. • Quantitative measurement of the amount of energy released by an earthquake. • Depends on the size of the fault that breaks. • Determined from seismic records. • Expressed on various magnitude scales like Richter scale. PAVAN KUMAR MEENA 29
- 30. Modified Mercalli scale PAVANKUMAR MEENA 30
- 31.
- 32.
- 33. Magnitude of Earthquake Magnitudeof an earthquake is the measure of energy released during an earthquake. Some of the common magnitude scales are: – ML - Local (Richter) magnitude – MW - Seismic Moment magnitude – MS - Surface wave magnitude – mb- Body wave magnitude PAVAN KUMAR MEENA 33
- 34. MW - SeismicMoment magnitude MW= log10A + 1.66 log10 Δ +2.0 A = Maximum ground displacement in micrometers Δ= Distance of seismograph from the epicenter, in degrees. ML - Local (Richter) magnitude ML= log10A(mm) +3 log10[8Δt (sec)]-2.93 Here A is the amplitude, in millimeters The S-P time, in seconds, makes Δt. mb- Body wave magnitude mb = log10A – log10T +0.01Δ + 5.9 A = Amplitude of P-waves in micrometers T = period of P-wave Δ = Distance of seismograph from the epicenter, in degrees. MW - Seismic Moment magnitude Moment Magnitude, Mw = 2/3 [log10M0(dyne-cm) –16] Moment Magnitude, Mw = - 6.0 + 0.67 log10M0(N.m) M0= DAμ where D is the average fault displacement in m, A is the total area of the fault surface in m2, and μ is the shear modulus of material along the fault plane in N/m2 (= 3x1010 N/m2 for surface crust and 7x1012 N/m2 for mantle) M0 is measured (Note: 1 dyne-cm = 1 × 10–7 newton-meter) PAVAN KUMAR MEENA 34
- 35. 40076 km =360° PAVAN KUMAR MEENA 35
- 36. S-P (S minusP) time formula: D= 𝑉𝑃𝑉𝑠 𝑉𝑃−𝑉𝑠 (𝑇𝑠 − 𝑇𝑝) T= 𝐷 𝑉 Ts > Tp Vp > Vs Ts= 𝐷 𝑉𝑠 Tp= 𝐷 𝑉𝑝 S-P Time difference Ts-Tp= 𝐷 𝑉𝑠 − 𝐷 𝑉𝑝 (Ts-Tp)=D( 𝑉𝑝−𝑉𝑠 𝑉𝑝𝑉𝑠 ) Where Vp= velocity of p wave Vs= velocity of s wave Tp= time period of p wave Ts= time period of s wave PAVAN KUMAR MEENA 36
- 37. THANK YOU PAVAN KUMARMEENA 37
- 38.