Analysis of Magnitude for Earthquake Detection using Primary waves and

Secondary waves

VARDHAMAN COLLEGE OF ENGINEERING(AUTONOMOUS)

Shamshabad – 501 218, Hyderabad.

Presented byShankar Murthy P

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Abstract

Introduction

Tectonic plates

Earthquake

Existing system

Proposed system

Experimentation Methodology

Conclusions

Future Enhancements

Presentation Flow

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Abstract

Earthquake is the natural disaster which occurs due to release of sudden energy.

It occurs due to imbalance in stress field and strength field.

Certain waves are released during earthquake, called Seismic waves, which are recorded over seismogram to calculate its intensity on Richter magnitude scale.

Many methods like Precursor techniques, Animal behavior have been propose to detect/predict the earthquake.

A new technique based on seismic waves is proposed to determine earthquake magnitude and few seismic parameters.

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Introduction

Earth It is also called as “Blue planet”, as it supports life

existence. It has four spheres namely Biosphere, Lithosphere,

Hydrosphere, Atmosphere.

Formation of earth Many theories have been proposed to support this

formation like Steady state theory, Cyclic Universe theory among all these, Big Bang theory is the Universal accepted theory.

Earth got cooled down due to continuous loss of heat energy which resulted in formation of several layers.

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Layers of earth1. Crust

2. Upper mantle

3. Transition

4. Lower mantle

5. D’’ layer

6. Outer core

7. Inner core

Liquid rocky materials

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Tectonic Plates

Tectonic plates are puzzle like structures which floats above the liquid rocky materials in the outer core.

The shaking of these tectonic plates results in shaking of earth surface, known as earthquake.

There are eight major and many minor tectonic plates.

Convergent, Divergent and Transform are the types of tectonic movements.

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Year Disaster Location

1931 Flood China

1887 Flood China

1556 Earthquake China

1970 Cyclone Bangladesh

2010 Earthquake Haiti

1926 Earthquake Antioch

1976 Earthquake China

2004 Tsunami Indian Ocean

1920 Earthquake Haiyuan

1975 Dam Failure China

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Earthquake

Earthquake is the sudden release of energy, which results due to imbalance between strength field of tectonic plates and stress field of heat energy released from molten liquid in outer core.

The location within the earth where the rock breaks is called Origin and the location on earth surface straight above the focus is called as Epicenter.

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The waves originate from focus are Primary waves (P-waves) and Secondary waves (S-waves).

Love waves, Stonely waves, Rayleigh waves originate from Epicenter.

The speed of P-waves is 4800 meters/sec and speed of S-waves is 3400 meters/sec.

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Existing System

Many different techniques have been proposed to detect the earthquake.1. Animal Behavior

2. Precursors

3. Co-seismic signal extractions

4. Early Earthquake Warning systems (EEWS)

These experimentation determined the occurrence of earthquake and alerts by issuing the alarm.

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Animal Behavior• Chinese conducted an experiment over animals like

snakes and rats.

• The unanimous behavior of those animals acts as an alert message before striking of earthquake.

• Japanese made an experiment over aquatic animals, as they have high perception of sensing the changes in electric fields.

• Since, the shaking of ground disturbs the earth’s electro-magnetic field which is immediately sensed by aquatic animals and behaves unanimously.

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Precursors

Precursor techniques are based on pattern evaluation which are formulated by the Radon emissions of elements like thoron, radon, uranium etc.

The pattern includes the relationship between intensity/velocities of the gases emitted and (2 x half life period of the element).

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Extraction of co-seismic signals

Co-seismic signals are extracted from the underground water.

Using HHT transform technique the frequency and energy of co-seismic signals are extracted using IMF (Intrinsic Mode Function) and EMD (Energy Mode Decomposition) functions respectively.

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Earthquake Early Warning Systems

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Proposed System

A new modern technical approach is proposed to detect the earthquake using seismic waves.

Analysis on seismic wave produces seismic parameters like energy, frequency, surface magnitude, wavelength and rupture area.

More detail experimentation is shown in the following flow chart diagram.

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Experimentation Methodology

Stage 1 : Seismic wave acquisition

Seismic waves are combination of P and S-waves which are recorded by a seismogram.

The seismic waves can be in two forms1. Image format

2. Signal format

Seismic signal is chosen, instead of seismic image, for the experimentation as it is more clear in representation and free from external noises.

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Seismic Image

Seismic Signal

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All the seismic signals are bought from1. SSA (Seismological Society of America)

2. JMA (Japan Metrological Agency)

3. USGS (United State Geological Survey)

4. SCEC (Southern California Earthquake data Centre)

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Stage 2: De-noising

Seismic signal may contain certain noisy data which are to be minimized.

Hence, these seismic signals are subjected to a technique called De-noising using Haar wavelet.

The following figure shows the levels in decompositions in de-noising process and the de-noised signal.

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Stage 3: FFT Spectrum

The de-noised signal is further processed to extract certain parameters which include 1. Histograms - frequency distribution graph.

2. Cumulative Histogram - cumulative frequency distribution graph.

3. Autocorrelation – computes periodicity in seismic signal.

4. FFT Spectrum – represents graphical relation between energy and frequency of seismic signal.

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Stage 4: Feature extraction from the graph

Parameters like energy and frequency of seismic signal can be extracted from FFT Spectrum.

The maximum energy level value is computed along with its frequency value from the following graph.

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Stage 5: Other seismic parameters

Other seismic parameters include, wavelength computed using formula

represents wavelength

represents speed of seismic wave

represents frequency

/v f

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Surface magnitude is computed using

E represents energy of seismic wave

Ms represents surface magnitude

Rupture area is computed using

Ms represents surface magnitude

A represents rupture area

10log |1.5 11.8 |sE M

10log |1.02 4.01|sA M

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Signal No. Energy

(ergs)

Frequency

(Hz)

Wavelength

(mts)

Surface

Magnitude(Ms)

Rupture Area

(cm2)

Earthquake

detection1 659 27.1 17.71 5.9 0.32 Yes

2 11306 25.5 18.82 5.1 0.10 Yes

3 11370 129.4 00.03 0.0 0.00 No

4 4197 61.2 07.84 5.4 0.19 Yes

5 1535 42.1 11.40 5.5 0.22 Yes

6 78000 80 00.41 0.0 0.00 No

7 191200 21.8 22.02 4.3 0.37 Yes

8 6700 104.9 00.32 0.0 0.00 No

9 195100 80 00.42 0.0 0.00 No

10 3212 24.5 19.59 5.5 0.21 Yes

11 1524 28.6 01.17 0.0 0.00 No

12 28770 16.5 29.09 4.8 0.01 Yes

13 19444 31.6 15.19 5.0 0.04 Yes

14 630 116.4 00.28 0.0 0.00 No

15 3348 24.45 01.37 0.0 0.00 No

Sample datasetICHCI’13

Based on the experimentation, the minimum surface magnitude fixed value is 4.

If the Ms 4 earthquake, else Ms No earthquake.

In order to predict the earthquake the seismic signals are to be extracted prior to the occurrence of earthquake, this can be done using GPR (Ground Penetrating Radar).

Those extracted signals are analyzed as above stated procedure to obtain parameters.

Since we can get Magnitude value we can predict the severity of earthquake in advance.

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Conclusions

The proposed methodology detects the earthquake with five seismic parameters.

Simple and modern technical approach.

Magnitude based detection/prediction.

Same approach can be used to predict the earthquake by extracting changes in seismic signals from underground.

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Future Enhancements

Different wavelets can be used instead of haar wavelet to de-noise.

Certain seismic parameters like seismic moment, volcanic eruption rates can be considered to improve efficiency.

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