جامعة الملك سعود مقرر 312جاف
قسم الجيولوجيا الاختبار النهائي 1424 هـ
FINAL EXAM
EARTHQUAKE SEISMOLOGY 1
DEPT. OF GEOLOGY & GEOPHYSICS
FIRST SEMESTR, 1424
ABDULLAH AL-AMRI NAME……………………..
ANSWER THE FOLLOWING QUESTIONS:
1. EXPLAIN THE MEANING OF THE FOLLOWING AS MUCH AS YOU CAN. ( 20 POINTS)
SINISTRAL & DEXTRAL FAULTS
ANISOTROPY
SEISMIC TOMOGRAPHY
BENNDORF RELATIONSHIP
REVERSE POLARITY
ASTHENOSPHERE
2. DISCUSS IN DETAIL THE FOLLOWING POINTS : ( 30 POINTS )
A. COMPARE SEISMIC CHARACTERISTICS BETWEEN EARTHQUAKES AND NUCLEAR EXPLOSIONS.
B. LIST SEISMIC EVIDENCE OF LIQUIDITY AND SOLIDITY OF THE CORE.
C. HOW VELOCITIES VARY WITH DEPTH PRODUCING DIFFERENT CHARACTERISTIC TRAVEL-TIME CURVES.
D . DISCUSS USING CROSS SECTION MAJOR STRUCTURE OF THE EARTH. BE SURE
TO INCLUDE VELOCITIES, DEPTHS, DENSITIES AND DISCONTINUITIES.
B. DISCUSS 670 KM DISCONTINUITY AND D” REGION.
3. ( 10 POINTS)
COMPUTE THE DEEPEST POINT REACHED IN THE EARTH BY A P-WAVE WHICH ENTERS THE TOP OF THE MANTLE AT AN ANGLE OF 600 FROM THE NORMAL. ASSUMING THE VELOCITIES OF THE LOWER CRUST AND UPPER MANTLE ARE 7.8 AND 8.2 KM / SEC. RESPECTIVELY.
4. ( 24 POINTS ) MULTIPLE CHOICE ( CHOOSE ONLY ONE ANSWER )
1. AT 400 KM DISCONTINUITY, OLIVINE CHANGES TO
a. SPINEL b. POST-SPINEL
c. PEROVSKITE d. MAGNESIUM OXIDES
2. QUALITY FACTOR VALUES ARE HIGHEST IN
a . INNER CORE b. UPPER MANTLE
C . LITHOSPHERE d. OUTER CORE
3. P-WAVE VELOCITY DROPS SHARPLY FROM 13.6 TO 8 KM/S AT
a. MOHO DISC. b. GUTTENBURG DISC.
c. 400 KM DISC. d. 670 KM DISC.
4. MAGNITUDE DETERMINATION FOR MICROEARTHQUAKES FROM
a. SIGNAL DURATION b. A / T
c. ACCELERATION d. NONE OF THE ABOVE
5. Mb & Ms ARE COINCIDED AT MAGNITUDE
a. 6.0 b. 6.5
c. 5.5 d. NEVER COINCIDED
6. MAXIMUMS ENERGY RELEASED FROM EQS ARE HIGHEST IN
a. SURFACE EQS. b. INTERMEDIATE EQS
C. DEEP EQS. d. EQ. SWARMS
7. NO. OF AFTERSHOCKS PER DAY DECREASES WITH INCREASING
a. TIME b. DEPTH
C. EPICENTRAL DISTANCE d. INTENSITY
8. SEISMIC ENERGY TRAVELS WITH
a. GROUP VELOCITY b. PHASE VELOCITY
c. PHASE & GROUP d. NONE OF THEM
9. SEISMIC WAVES TRANSMITTED OUTER CORE ARE
a. SKS b. PKP
c. PPP d. PcP
10. SEISMIC RECORD IS KNOWN AS
a. SEISMOMETER b. SEISMOSCOPE
c. SEISMOGRAPH d. SEISMOGRAM
11. WHEN THE WAVES ARE DISPERSIVE IN DEEP WATER, THIS MEANS
a. Vp>Vs b. Vp < Vs
c. Vp = Vs d. NO RELATION
12. THE ANGLE BETWEEN THE FAULT PLANE AND THE HORIZONTAL IS
a. STRIKE b. DIP
C. AZIMUTH d. SLIP VECTOR
5. CONSIDER THREE EARTHQUAKES LOCATED ALONG THE ARABIAN PLATE
BOUNDARIES , IN THE CENTRAL RED SEA, GULF OF AQABAH AND ZAGROS
MOUNTAINS.
ASSUMING THE FAULT LENGTH OF EACH EQ. IS 300 KM, THE AVERAGE
DISPLACEMENT IS 5 M AND THE RIGIDITY OF THE FAULT ZONE IS 3 X 1011 dyne / cm2
( 12 POINTS).
A. DRAW THE EXPECTED FOCAL PLANES FOR THE THREE EQS.
B. IN WHAT DEPTH RANGE WOULD YOU EXPECT EACH OF THE THREE EVENTS TO OCCUR.
C. WHAT WOULD BE THE SEISMIC MOMENT OF THE LARGEST EVENT FOR EACH EQ.
D. ESTIMATE MOMENT MAGNITUDE (Mw ) AND SEISMIC ENERGY FOR EACH EVENT.