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SH Vietnam
Seismic Zoning of Vietnam
Definition of seismic zones
Magnitude discretization
SH Vietnam
Seismic Zoning of Vietnam
Smoothing of magnitude
Selection of grid points within seismogenic zones
SH Vietnam
Seismic Zoning of Vietnam
Distribution of peak displacements
SH Vietnam
Deterministic Seismic Zoning of Vietnam
Distribution of peak velocities
SH Vietnam
Deterministic Seismic Zoning of Vietnam
Distribution of Design Ground Acceleration
Vietnam
Seismotectonic map of Vietnam
Vietnam
Map of the Southern Chinese Sea,
with the locations of the six selected tsunamigenic seismic sources (the red pins correspond to the epicenters),
and of the seven selected receiver sites (yellow pins) along the Vietnam coasts.
Tsunami scenarios for the Vietnam’s coasts
Vietnam
Tsunami computation - Snapshots for S1
Snapshots of the tsunami wave height for a Mw=8.0 event located at Source 1 position
Vietnam
Tsunami computations - Mw=7.0
Distribution of the maximum positive
tsunami wave heights along the Vietnam coasts computed
considering the six sources for Mw=7.0
Vietnam
Tsunami computations - Mw=7.5
Distribution of the maximum positive
tsunami wave heights along the Vietnam coasts computed
considering the six sources for Mw=7.5
Vietnam
Tsunami computation - Mw=8.0
Distribution of the maximum positive
tsunami wave heights along the Vietnam coasts computed
considering the six sources for Mw=8.0
vietf0tsz.tmx
100˚
100˚
102˚
102˚
104˚
104˚
106˚
106˚
108˚
108˚
110˚
110˚
112˚
112˚
114˚
114˚
6˚ 6˚
8˚ 8˚
10˚ 10˚
12˚ 12˚
14˚ 14˚
16˚ 16˚
18˚ 18˚
20˚ 20˚
22˚ 22˚
100.0
300.0
500.0
952.5D (cm)
1000.0
Vietnam
Tsunami scenarios - Source 1
Synthetic tsunamigrams
computed at the different sites for Source 1 scenario
Site Khan Hoa Vung Tau Bac LieuQuang Ninh
Distance (km) 911 1028 1160 1736
Tmax (min) 205 229 261 397
Tmax − Tmin(min) 6 6 6 7
Strike max (°) 30 15 7.5 60
Max(cm) M=7 16 14 13 10
Max(cm) M=7.5 93 84 76 56
Max(cm) M=8 378 345 314 225
-500
-400
-300
-200
-100
0
100
200
300
400
300 350 400 450 500 550 600 650 700
Hei
ght (
cm)
Time (min)
Khan_Hoa_1
Vung_Tau_1
Bac_lieu_1
Quang_Ninh_1
Vietnam
Tsunami scenarios - Source 2
Synthetic tsunamigrams
computed at the different sites for Source 2 scenario
Site Khan Hoa Bin Dinh Quang NinhDistance (km) 571 598 1214
Tmax (min) 150 156 312
Tmax − Tmin(min) 3 3 4
Strike max (°) 0 15 52.5
Max(cm) M=7 11 11 5
Max(cm) M=7.5 64 60 30
Max(cm) M=8 290 276 150
-400
-300
-200
-100
0
100
200
300
0 100 200 300 400 500 600 700
Hei
ght (
cm)
Time (min)
Khan_Hoa_2
Binh_Dinh_2
Quang_Ninh_2
Khan_Hoa_2_ext
Binh_Dinh_2_ext
Quang_Ninh_2_ext
Vietnam
Tsunami scenarios - Source 3
Synthetic tsunamigrams
computed at the different sites for Source 3 scenario
Site Da NangQuang Ninh Vinh Bin Dinh
Distance (km) 268 366 392 478
Tmax (min) 210 258 277 338
Tmax − Tmin(min) 12 13 12 12
Strike max (°) 120 52.5 0 90
Max(cm) M=7 56 50 49 44
Max(cm) M=7.5 314 285 276 250
Max(cm) M=8 823 744 720 654
-400
-200
0
200
400
600
800
1000
0 50 100 150 200 250 300 350 400
Hei
ght (
cm)
Time (min)
Danang_3
Quang_Ninh_3
Vinh_3
Binh_Dinh_3
Danang_3_Ext
Quang_Ninh_3_Ext
Vinh_3_Ext
Binh_Dinh_3_Ext
Vietnam
Tsunami scenarios - Source 4
Synthetic tsunamigrams
computed at the different sites for Source 4 scenario
Site Vung Tau Bac Lieu
Distance (km) 169 275
Tmax (min) 118 187
Tmax − Tmin(min) 13 13
Strike max (°) 60 0
Max(cm) M=7 68 54
Max(cm) M=7.5 384 308
Max(cm) M=8 1022 820
-500
0
500
1000
1500
2000
0 50 100 150 200 250 300 350 400
Hei
ght (
cm)
Time (min)
Vung_Tau_4
Bac_Lieu_4
Vung_Tau_4_Ext
Bac_Lieu_4_Ext
Vietnam
Tsunami scenarios - Source 5
Synthetic tsunamigrams
computed at the different sites for Source 5 scenario
Site Khan Hoa Vung Tau Bac Lieu
Distance (km) 195 266 456
Tmax (min) 137 187 322
Tmax − Tmin(min) 13 13 13
Strike max (°) 60 0 157.5
Max(cm) M=7 61 54 42
Max(cm) M=7.5 342 305 235
Max(cm) M=8 917 806 622
-400
-200
0
200
400
600
800
1000
1200
0 50 100 150 200 250 300 350 400
Hei
ght (
cm)
Time (min)
Khan_Hoa_5
Vung_Tau_5
Bac_Lieu_5
Khan_Hoa_5_Ext
Vung_Tau_5_Ext
Bac_Lieu_5_Ext
Vietnam
Tsunami scenarios - Source 6
Synthetic tsunamigrams
computed at the different sites for Source 6 scenario
Site Da Nang Vinh Quang Ninh
Distance (km) 141 306 423
Tmax (min) 98 216 299
Tmax − Tmin(min) 13 13 13
Strike max (°) 90 30 75
Max(cm) M=7 74 51 43
Max(cm) M=7.5 419 287 243
Max(cm) M=8 1119 764 653
-1000
-500
0
500
1000
1500
0 100 200 300 400 500 600 700
Hei
ght (
cm)
Time (min)
Danang_6
Vinh_6
Quang_Ninh_6
Danang_6_Ext
Vinh_6_ext
Quang_Ninh_6_Ext
Vietnam
RemarksThe shoaling and other amplification phenomena due to the local morphology, could increase that amplitude up to some factors, enough to cause small damages and inundations, specially if coinciding with the high tide or a sea storm.
The larger is the focal depth the smaller is the maximum amplitude. According to the modal summation theory, when a source is located deeper inside the Earth interior it is less efficient in exciting the high frequencies, so their contribute to the total displacement at the sea bottom is reduced. It follows that shallow earthquakes are more capable than deep ones to generate tsunamis.
Increasing the epicentral distance, the maximum amplitude decreases, if we exclude local effects. This is due to the fact that the radiation pattern is attenuated by the geometrical spreading as we move the site far from the source.
The water layer thickness affects amplitude in two ways: i) Where the depth of the liquid layer is thicker tsunami waves are faster and the geometrical spreading is more intense. ii) Sources set under a thinner water layer are less effective in generating tsunamis
Vietnam
RemarksEvents with magnitude M=8.0 (which is nearly the maximum magnitude in many regions of the South China domain) could generate tsunamis with amplitudes of a few meters, in agreement with a number of historical events reported in the catalogues
The low level of monitoring of the South China Sea and the high degree of anthropization of the Vietnam coasts (and their high level of vulnerability) could make the risk quite high.
We hope that the results can be used as a preliminary knowledge basis to: design early warning systems, reduce tsunami risk and plan land-use for the Vietnam coasts.