Strong Ground Motions of the 2024
Taiwan EarthquakeIISEE, Building Research InstituteApr. 8, 2024

BRI

Observed PGAs/PGVs (3 comp.)
Epicenter

cm/s2○: TSMIP(CWA) stations, □: P-Alert stations

cm/s

2024/04/02 23:58(UTC)
Mw: 7.4 (USGS)
Depth: 34.8km (USGS)

Observed PGAs/PGVs vs GMPE (Si & Midorikawa, 1999)

TSMIP stations

P-Alert stations※ Horizontal axis is not the “shortest distance to the fault”.
※ PGA/PGV values are the larger of the maximum values of NS and EW components.
※ Interplate earthquake (depth=34.8 km) is assumed for the estimation.
※ Estimated values beyond 100 km (dashed line) are shown as reference values.

Pseudo-velocity response (pSv: 1‒2 s, h=5%)*H008 (9th floor)

F045

W475
D001

F048
F049
W028
F068
F015
F051
W022

BRI

BRI

Acc. (cm/s²)

Acceleration

2500

NS(cm/s/s) (peak: -378.9 cm/s²)

Acceleration Response (h=5%)2500

Sa-Sd curve (h=5%)
0.5s

500
0EW(cm/s/s) (peak: -479.7 cm/s²)

0-500
500

UD(cm/s/s) (peak: -282.9 cm/s²)

2000

2000

1500

1500Sa (cm/s²)

-500
500

Sa (cm/s²)

Acc. (cm/s²)

Acc. (cm/s²)

Ground motion at D001

1000NS(cm/s/s)
EW(cm/s/s)
UD(cm/s/s)

500

00102030

40Time (s)0001/01/01 00:00:00 at : , Intensity: 5.9

50

60

70

80

1000

1.5s

NS(cm/s/s)2s
2.5s
EW(cm/s/s)
UD(cm/s/s)

5000-5001s

00123
Period (s)450102030
Sd (cm)

4050

BRI

Acc. (cm/s²)

1500

NS(cm/s/s) (peak: 354.9 cm/s²)

Acceleration Response (h=5%)

1500

Sa-Sd curve (h=5%)
1sAcceleration0.5s

5000-500500

1000
EW(cm/s/s) (peak: 479.0 cm/s²)

500.5s2NS(cm/s/s)
3s
EW(cm/s/s)
UD(cm/s/s)

NS(cm/s/s)
EW(cm/s/s)
UD(cm/s/s)

00-50010203040Time (s)0001/01/01 00:00:00 at : , Intensity: 5.8

50

60

702s

500

UD(cm/s/s) (peak: -215.2 cm/s²)0s
1.5

Sa (cm/s²)

0-500
500

1000

Sa (cm/s²)

Acc. (cm/s²)

Acc. (cm/s²)

Ground motion at W022

8000123Period (s)450102030
Sd (cm)

4050

BRI

Acc. (cm/s²)

1500

Sa-Sd curve (h=5%)s

NS(cm/s/s) (peak: -339.0 cm/s²)

Acceleration Response (h=5%)

1.5

1500

1s

Acceleration

0.5s

500
0-500
500

1000
EW(cm/s/s) (peak: -210.5 cm/s²)

-500
500

Sa (cm/s²)

0500

NS(cm/s/s)
EW(cm/s/s)
UD(cm/s/s)

0-500
2030

40
Time (s)0001/01/01 00:00:00 at : , Intensity: 5.9

50

60

703s

NS(cm/s/s)
EW(cm/s/s)
UD(cm/s/s)

0102.5s

500

UD(cm/s/s) (peak: -168.3 cm/s²)

02s

1000

Sa (cm/s²)

Acc. (cm/s²)

Acc. (cm/s²)

Ground motion at W028

80

00123Period (s)450204060
Sd (cm)

80100

BRI

Acc. (cm/s²)

1500

NS(cm/s/s) (peak: 267.0 cm/s²)

Acceleration Response (h=5%)

1500

Sa-Sd curve (h=5%)
1sAcceleration

0.5s

500
0-500
500

1000
EW(cm/s/s) (peak: -271.7 cm/s²)

500.5s2NS(cm/s/s)
3s
EW(cm/s/s)
UD(cm/s/s)

NS(cm/s/s)
EW(cm/s/s)
UD(cm/s/s)

00-50010203040Time (s)0001/01/01 00:00:00 at : , Intensity: 5.75060702s500UD(cm/s/s) (peak: -347.3 cm/s²)0s
1.5

Sa (cm/s²)

0-500
500

1000

Sa (cm/s²)

Acc. (cm/s²)

Acc. (cm/s²)

Ground motion at W475

80

00123Period (s)450102030
Sd (cm)4050

Response acceleration spectrum Sa and response periods
Colored Line: Taiwan Earthquake strong-motion(Equivalent damping factor＝5％)

BRI

BRI

Sa - Sd curve and response periods
Colored Line: Taiwan Earthquake strong-motion(Equivalent damping factor＝15％)

Base shear coefficient CB＊(＊effective mass conversion)

SummaryBRI•

Large ground motions were observed over a wide area in Taiwan (not only in the eastpart near the epicenter but also in the west part).

•Strong-motion records at least 10 sites in and near Hualien show responses slightly
above 165 cm/s in the period of 1-2 seconds.

•The response acceleration (Sa) of the East-West (EW) components of D001(Hualien) showed large values at around the period of 0.5 seconds. The North-South(NS) components of W028 and W022 (Hualien) showed large values at around 1.0
seconds.

•From the Sa-Sd curve assuming a 15% equivalent damping ratio, the observation data
for the Taiwan earthquake in 2024 were smaller than past typical earthquakes inJapan.
Acknowledgement:
We used strong motion data provided by P-Alert, TSMIP(CWA), NIED(K-NET, KiK-net), JMA, and, RTRI.
Sa-T and Sa-Sd were calculated using the View Wave by Kashima, BRI.