20 09 2005 Marwa Earthquake Potential Tanzania

8/12/2019 20 09 2005 Marwa Earthquake Potential Tanzania

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Overview of Earthquake Potential inCentral Part of Tanzania

Ernest M.M.Marwa

Sokoine University of Agriculture,Tanzania


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Map of Tanzania


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SEISMIC ACTIVITY IN REGION(Continuing)

The Rift System in the Region is defined bybroad zones of faults with a series of tiltedblocks.The faults in some places follow the

Precambrian weak zones

The paper contains seismic data in the

region from 1894 to 2002


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Recent strong earthquakes inTanzania

BABATI 5TH JULY 1964 MG 6.3

RUKWA 18THAUG. 1994 MG 6.4

KIPILI 2ND OCT. 2002 MG 6.5

BARIADI 18TH MAY 2002 MG 5.5

DODOMA 4TH NOV. 2002 MG 5.6


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Tectonic structures of Tanzania(Source: Iranga, 1991)

Davies ridge

(Chapola,1997)


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Ground structures and earthquake epicentres in CentralRegion (1894-2002)


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Seismic observatory network

KEY:

1. DOD = Dodoma

2. ARTT = Arusha

3. ITBT = Itumba

4. PDHT = Panda Hill

5. TDMT = Tunduma

6. ITKT = Itaka


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Seismic source zones of Tanzania

e se sm c azar map o anzan a s ow ng se sm c


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e se sm c azar map o anzan a s ow ng se sm cmean Peak Ground Acceleration (PGA) in cm/s2.

(Analysis done using SEISAN software, Mmari, 2004)


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RECORDED EARTHQUAKES (1894-2002)

0

5

10

15

20

25

30

35

40

45

50

1894 1919 1947 1957 1962 1967 1972 1978 1983 1994 2002

YEAR

FREQU

ENCY


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Range of recorded earthquake magnitudes

(1894-2002)

0

10

20

30

40

50

60

70

2.6-

2.8

2.8-

3.0

3.0-

3.2

3.2-

3.4

3.4-

3.6

3.6-

3.8

3.8-

4.0

4.0-

4.2

4.2-

4.4

4.4-

4.6

4.6-

4.8

4.8-

5.0

5.0-

5.2

5.2-

5.4

5.4-

5.6

5.6-

5.8

5.8-

6.0

6.0-

6.2

6.2-

6.4

Range of earthquake magn itudes

Numbero

foccurrences


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Monthly frequency distribution of earthquakes

10

15

20

25

30

35

40

45

50

55

60

Jan. Feb. March April M ay June July Aug. Sept. Oct. Nov. Dec.

MONTHS

FREQU

ENCY


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CONCLUDING REMARKS

The Central Tanzania is prone to earthquakes

The maximum earthquake magnitudes from 1894 and2002 range between 5.0 and 6.4, dominant

magnitudes are 4.0-4.8.There is an urgent needs of establishing an up to dateGIS seismic data base for planning of land use

There is a need of enforcing the existing building code& regulations to minimize possible future seismicrisks.

With increase in population, public awareness andeducation on earthquake hazards and risks should be

done at all levels.

Documents

20 09 2005 Marwa Earthquake Potential Tanzania