Transcript Tsunami Intensity: A Valuable Parameter of Multiple Usefulness

Tsunami Intensity:
A Valuable Parameter of Multiple
Usefulness
Papadopoulos G.A., Daskalaki E., Fokaefs A.
Institute of Geodynamics
National Observatory of Athens, Greece
[email protected]
Intensity of natural phenomena
Size of a natural event is traditionally measured by the intensity that
is the impact of the event
o
o
o
o
Examples
Beaufort 12-point scale for wind
Saffir-Simpson 5-point scale for typhoons
Mercalli-Sieberg 12-point scale for earthquakes
EMS-98 new 12-point scale for earthquakes
Magnitude of natural phenomena
Modern measure of the size of a natural event is magnitude which
expresses the energy of the event
Examples
o Richter and moment-magnitude scales for earthquakes
o Newhall-Self 8-point scale for volcanic eruptions
o Iida scale for tsunamis
Tsunami Scales
Type of Tsunami
Analogy to Earthquake Scales
Sieberg [1927]
primitive 6-point intensity
scale
early intensity scales
Ambraseys [1962]
improved 6-point intensity
scale
improved intensity
scales
Shuto [2001]
developed 6-point intensity scale
developed intensity
scales
Papadopoulos
& Imamura [2001]
new 12-point intensity scale
new EMS ’92 and ’98
12-point intensity scale
Imamura - Iida
[40’s, 50’s & 60’s]
primitive magnitude scale
local Richter magnitude
scale
Soloviev [1970]
primitive magnitude scale
local Richter magnitude
Abe [80’s & 90’s]
magnitude scale
surface-wave magnitude scale
Murty - Loomis [1980]
magnitude scale
moment – magnitude scale
Intensity Scales
Magnitude Scales
Tsunami intensity
o Size of a tsunami based on the macroscopic observation of tsunami’s
effect on humans, objects, including various size of marine vessels and
buildings
o What factors control the disastrous effects of the tsunami?
- humans,
- effects on objects (e.g. vessels of variable size),
- nature (e.g. ground erosion),
- damage to buildings.
12-point tsunami intensity scale
o
o
Incorporates twelve divisions
Is consistent with several 12-grade seismic intensity scales.
(Papadopoulos & Imamura, 2001)
a.
b.
c.
Independent from physical parameters
Sensitive to the small difference in tsunami effects
Detailed description of each division by taking into account all possible
tsunami impacts on human and natural environment
Empirical correlation between the intensity K, introduced by
Papadopoulos & Imamura (2001) and the quantities H and i
introduced in formula by Shuto (1993)
K
I-V
VI
VII-VIII
IX-X
XI
XII
H (m)
<1.0
2.0
4.0
8.0
16.0
32.0
i
0
1
2
3
4
5
The 12-point scale has been used in:
o Indian Ocean after the tsunami of 2004 (Narayan J.P. et al., Pure &
Applied Geophysics, 163, 1279p., 2006; Rossetto T. et al., Natural
Hazards, 2006; Maheshwari et al., Earthquake Spectra, 23/III, S475p.;
Chang et al., Earthquake Spectra, 23/III, S863p.)
o Black Sea (Yalciner A. et al., J. Geophys. Res., 109, C12023p., 2004)
o Mediterranean Sea (Tinti, S. et al., Marine Geology, 225, 311p., 2006)
o Azores Islands (Andrade C, J. Volcanol. & Geoth. Res., 156, 172p., 2006)
o Australia (Dominey-Howes, D., Marine Geology, 239, 99p., 2007)
o Indonesia (Lavinge et al., Nat. Hazards Earth Syst. Sci., 177p., 7, 2007)
o Portugal (Baptista et al., NHESS, 2009)
Further Presentation of the 12-scale can
be found in the following books:
o Β. Levin & Μ. Nosov: Physics of Tsunamis & Kindred Phenomena in
Ocean, Moscow, Janus-K, 2005; Physics of Tsunamis, Springer, 2009.
o Tsunami Glossary from the Intergovernmental Oceanographic
Commission of UNESCO and the International Tsunami Information
Centre, USA, 20p, 2006.
o M. Woods & Μ.B. Woods: Tsunamis, Lerner Publ. Comp., Minneapolis,
2007.
o E. Guidoboni & J.E. Ebel: Earthquakes & Tsunamis in the Past: A guide
to techniques in historical seismology, 2009.
Possible applications of the new 12-point
tsunami intensity scale
o Revision of tsunami catalogues
o Mapping the geographical distribution of the impact of past
tsunamis
o Description of the tsunami impact by intensity isolines
o Construction of empirical attenuation laws of the tsunami impact
o Tsunami statistics
Indian Ocean 2004 Intensities
Observation points: 206
Indian Ocean 2004 Intensities
Observation points: 53
Indian Ocean 2004 Intensities
Observation points: 149
Tsunamicity of Greece:
the highest in the Euro-Mediterranean region
Papadopoulos & Fokaefs, 2005
9 July 1956
earthquake M=7.5
tsunami: 15-20m
The tsunami source 9th July 1956 event
VI-VIII
VI-VIII
IV
V
III
Wave attenuation of 9th July 1956
16
A t (m)
14
3 largest K's / 50 Km
A t = 86.41x Δ -0.8208
12
r 2 = 0.54
10
8
6
4
Δ(km)
2
K
10
8
6
4
2
0
K = 7.2144e
-0.0028Δ
R2 = 0.743
Δ (Km)
0
100
200
300
400
0
0
100
200
300
400
Attenuation law /epicentral distances
3 largest intensities K per 50km /
epicentral distances
Earthquake Statistics
↘ Magnitude-frequency or G-R relation (Gutenberg and Richter, 1944)
extensively used in seismology to describe the exponential decrease of the
event frequency, Nc, with the increase of the event magnitude, M:
log N c  a  bM
20/10/2005 - 21/11/2005
log N
3.00
Log N = -1.83 M L + 8.45
2
R = 0.995
2.00
1.00
ML
0.00
2.0
3.0
4.0
5.0
Application of the tsunami statistics:
West Hellenic Arc
o Intensity-frequency → equivalent to the magnitude-frequency or G-R
relation (Gutenberg & Richter, 1944) used in seismology: log Nc  ac  bK
o Describes the exponential degree of the event frequency with the
decrease of the event size
o Excluding frequencies of events
with K ≥ 3:
log N c  3.3  0.3K
From log Nc  ac  bK it comes out that
the mean repeat time, TK , of events of
intensity equal to or larger than K is:
TK  10bK a or the mean yearly rate of
1
occurrence is r 
TK
maximum intensity, Kmax, which is the
most probable to be observed within
time interval t is given by the
a  log t
expression K max 
b
K Tk=10bK-a
2
4
3
9
4
18
5
36
6
73
7
150
8
306
9
626
10
1277
t (years)
10
50
100
1000
r =1/Tk last event
0.23646
1898
0.11581
1983
0.05672
1899
0.02778
2000
0.01361
1866
0.00666
1867
0.00326
1612
0.00160
0.00078
365
Kmax
3.2
5.5
6.4
9.7
Poissonian Statistics
o From the mean yearly rate of tsunami occurrence we calculated the
probability, P( x  1)t , to observe at least one tsunami of intensity
K equal to or larger than a given value within particular time
interval, t.
e (  rt )( rt )
o The probability to observe x events in t years is P( x)t 
x!
x
while the probability to observe at least one tsunami event in t
years is
P( x  1)t  1  P( x  0)t
t (years)
1
10
100
1000
K≥2
0.21
0.91
1.00
1.00
K≥4
0.06
0.43
0.99
1.00
K≥6
0.01
0.13
0.74
1.00
K≥8 K≥10
0.003 0.001
0.03 0.01
0.28 0.08
0.96 0.54
Seismic damage: e.g. Bucharest, 4 March, 1997, M= 7.4
intensity map
shake map
SAFER Project, EU-FP6, 2009, Partner NIEP, Romania
Possible future application for tsunamis
o Construction of expected tsunami damage maps in terms of
tsunami intensity in analogy to expected seismic damage
o This requires:
- inundation zone from numerical simulation
- Vulnerability analysis
- Damage scenario
Thank you for your attention