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Interpretation of geological features, Lecture notes of Engineering Geology

University of Petroleum and Energy Studies Engineering Geology

Seismic is the best techniques for oil and gas exploration.

Typology: Lecture notes

2018/2019

Uploaded on 10/28/2019

vivek-aryan 🇮🇳

1 document

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Seismology and the Earth’s Deep Interior Seismogram Interpretation

Seismogram Interpretation

• Travel times in the Earth

• Ray paths, phases and their name

• Wavefields in the Earth: SH waves, P-SV waves

• Seismic Tomography

• Receiver Functions

Partial preview of the text

Download Interpretation of geological features and more Lecture notes Engineering Geology in PDF only on Docsity!

Seismogram Interpretation Seismogram Interpretation

• Travel times in the Earth

• Ray paths, phases and their name

• Wavefields in the Earth: SH waves, P-SV waves

• Seismic Tomography

• Receiver Functions

Seismogram Example Seismogram Example

4400s

Long-period transverse

displacement for an

earthquake at 600km

depth recorded at 130o

(synthetic).

How can we extract

information from

seismograms on Earth

structure?

-> identify phases

-> pick travel times

-> collect travel times

as

a function of distance

History of Travel-Times History of Travel-Times

(^) Harrold Jeffreys and Keith Bullen (1940), (J-B) Remarkable accuracy for teleseismic travel times (below 1%)!
Herrin et al. (1968), with well located earthquakes.
(^) Dziewonski and Anderson (1981), Preliminary Reference Earth Model (PREM)
(^) Kennett and Engdahl (1991), most accurate radially symmetric model (iasp91)
(^) (2000), The first 3-D reference model with travel times?

Ray Paths in the Earth (1) Ray Paths in the Earth (1)

Particular phases at teleseismic distances are named after the wave types (P or S), regions they pass along their path, and emergence angle at the source (upwards or downwards).

Ray Paths in the Earth - Names Ray Paths in the Earth - Names

P P waves

S S waves

small p depth phases (P)

small s depth phases (S)

c Reflection from CMB

K wave inside core

i Reflection from Inner core

boundary

I wave through inner core

diff diffractions at CMB

Examples:

PcP, pPcS, SKS, PKKKP, PKiKP, PKIKP, sSS, pSSS,

sPcS, etc.

Wavefields in the Earth: SH waves Wavefields in the Earth: SH waves

Red and yellow

color denote

positive and

negative

displacement,

respectively.

Wavefield for

earthquake at

600km depth.

Wavefields in the Earth: SH waves Wavefields in the Earth: SH waves

Red and yellow

color denote

positive and

negative

displacement,

respectively.

Wavefield for

earthquake at

600km depth.

Wavefields in the Earth: SH waves Wavefields in the Earth: SH waves

Red and yellow

color denote

positive and

negative

displacement,

respectively.

Wavefield for

earthquake at

600km depth.

Wavefields in the Earth: P-SV waves Wavefields in the Earth: P-SV waves

Red and yellow color denote positive and negative vertical displacement, respectively. Left: homogeneous mantle, right: realistic spherically symmetric model (Preliminary Reference Earth Model, PREM ) Wavefield for explosion at 600km depth.

Wavefields in the Earth: P-SV waves Wavefields in the Earth: P-SV waves

Red and yellow color denote positive and negative vertical displacement, respectively. Left: homogeneous mantle, right: realistic spherically symmetric model (Preliminary Reference Earth Model, PREM ) Wavefield for explosion at 600km depth.

Wavefields in the whole Earth: P waves Wavefields in the whole Earth: P waves

Red and blue colors denote positive and negative vertical displacement, respectively. Spherically symmetric model (Preliminary Reference Earth Model, PREM ) Wavefield for explosion at surface. Time: 150s

Wavefields in the whole Earth: P waves Wavefields in the whole Earth: P waves

Red and blue colors denote positive and negative vertical displacement, respectively. Spherically symmetric model (Preliminary Reference Earth Model, PREM ) Wavefield for explosion at surface. Time: 450s

Wavefields in the whole Earth: P waves Wavefields in the whole Earth: P waves

Red and blue colors denote positive and negative vertical displacement, respectively. Spherically symmetric model (Preliminary Reference Earth Model, PREM ) Wavefield for explosion at surface. Time: 1050s

Wavefields in the whole Earth: P waves Wavefields in the whole Earth: P waves

Red and blue colors denote positive and negative vertical displacement, respectively. Spherically symmetric model (Preliminary Reference Earth Model, PREM ) Wavefield for explosion at surface. Time: 1350s

Interpretation of geological features, Lecture notes of Engineering Geology

Related documents

Partial preview of the text

Download Interpretation of geological features and more Lecture notes Engineering Geology in PDF only on Docsity!

Seismogram Interpretation Seismogram Interpretation

• Travel times in the Earth

• Ray paths, phases and their name

• Wavefields in the Earth: SH waves, P-SV waves

• Seismic Tomography

• Receiver Functions

Seismogram Example Seismogram Example

4400s

Long-period transverse

displacement for an

earthquake at 600km

depth recorded at 130o

(synthetic).

How can we extract

information from

seismograms on Earth

structure?

-> identify phases

-> pick travel times

-> collect travel times

as

a function of distance

History of Travel-Times History of Travel-Times

Ray Paths in the Earth (1) Ray Paths in the Earth (1)

Ray Paths in the Earth - Names Ray Paths in the Earth - Names

P P waves

S S waves

small p depth phases (P)

small s depth phases (S)

c Reflection from CMB

K wave inside core

i Reflection from Inner core

boundary

I wave through inner core

diff diffractions at CMB

Examples:

PcP, pPcS, SKS, PKKKP, PKiKP, PKIKP, sSS, pSSS,

sPcS, etc.

Wavefields in the Earth: SH waves Wavefields in the Earth: SH waves

Red and yellow

color denote

positive and

negative

displacement,

respectively.

Wavefield for

earthquake at

600km depth.

Wavefields in the Earth: SH waves Wavefields in the Earth: SH waves

Red and yellow

color denote

positive and

negative

displacement,

respectively.

Wavefield for

earthquake at

600km depth.

Wavefields in the Earth: SH waves Wavefields in the Earth: SH waves

Red and yellow

color denote

positive and

negative

displacement,

respectively.

Wavefield for

earthquake at

600km depth.

Wavefields in the Earth: P-SV waves Wavefields in the Earth: P-SV waves

Wavefields in the Earth: P-SV waves Wavefields in the Earth: P-SV waves

Wavefields in the whole Earth: P waves Wavefields in the whole Earth: P waves

Wavefields in the whole Earth: P waves Wavefields in the whole Earth: P waves

Wavefields in the whole Earth: P waves Wavefields in the whole Earth: P waves

Wavefields in the whole Earth: P waves Wavefields in the whole Earth: P waves