Li Zhao
Institute of Earth Sciences, Academia Sinica.

Outline• A brief review of the development of 3D models
for the Taiwan region• Recent advancement with improved datasets• Applications of ground-truth first-arrival times
from TAIGER project• Contribution from surface wave data
• Future directionTectonic Setting of Taiwan
Eurasia

TaiwanPhilippineSea• Oblique convergent boundary
between Eurasia and thePhilippine Sea plates• Active subductions: northward
in the northeast and eastward inthe south• Arc-continent collision betweentwo subductions• Continental margin in the westand accretion in the east
Chang et al. (2001)

Taiwan in Regional Studies
Eurasia

TaiwanLi et al. (2006)

PhilippineSea

Development of 3D Models of Taiwan
First generation: limited travel time data at a small numberof stations (< 100) from numerous local earthquakes
Roecker et al. (1987); Shin & Chen (1988); Rau & Wu (1995);
Ma et al. (1996).

Second generation: more extensive travel time data at morestations from numerous local (and teleseismic) events
Kim et al. (2005); Wang et al. (2006); Wu et al. (2007).

Third generation: travel time data at numerous stations(TAIGER project) from local, teleseismic and active sources
Kuo-Chen et al. (2012).

Third Generation: the TAIGER Project
TAiwan Integrated GEodynamics Research Project1.

Passive: land and marine
broadband deployments.

2.

Active:Land explosions• 10 explosions (twotransects)• 1400 recording sites
 Marine seismic surveys• Six transects
3.

Other geophysical means.

Kuo-Chen (2011)

Comparison of 2nd and 3rd Generation Models
KC12 Kuo-Chen et al. (2012)

Kuo-Chen (2011)

K05 Kim et al. (2005)

W07 Wu et al. (2007)

Comparison along a Central E-W Transect
KC12K05

W07
Kuo-Chen (2011)

Comparison along a Central N-S Transect
KC12K05

W07
Kuo-Chen (2011)

Model Evaluation Using Ground-Truth Data
Ground-truth data comes from:
10 Explosions by the TAIGER project
Total number of land receiver sites: ~1000
Hand-picked first-arrival times (error < 0.1s)
Total number of reliable picks: ~ 6000
Shot Size
Date (GMT)CWB Longitude Latitude Elev.
Point (kg) dd/mm/yyyy hh:mm:ss.sss ML(GS84)(m)
S1 1000
S2750
S3500
S3P 1500
S4750

02/27/2008 17:01:49.486 3.02 120.238026 23.508864 602/27/2008 17:30:57.350 2.62 120.421259 23.423385 2002/26/2008 18:02:45.860 1.89 120.714736 23.280129 650
02/26/2008 17:32:43.290 1.78 120.626749 23.136994 335
02/28/2008 17:02:08.560 2.30 121.141722 23.132877 390

N1750
N2750
N3750
N3P 3000
N4 1000

03/06/2008 17:03:23.068 2.56 121.045868 24.793562 55
03/06/2008 17:34:56.364 1.55 121.235817 24.675632 590
03/04/2008 18:01:17.988 2.10 121.487867 24.576938 405
03/04/2008 17:01:17.824 2.67 121.487867 24.576938 405
03/05/2008 17:03:40.008 2.43 121.811684 24.446901 6

Travel Time Residuals of Models K05 and W07
OBS-K05

OBS-K05

OBS-W07

N3P

OBS-W07

N3P

S3-2-101

S32

Traveltime residual (sec)
Lin et al. (2011)

Statistics of Travel Time Residuals
Picks from Coastal Plain

All picks

Model
K05

RMS (s)0.75

Mean (s)-0.27ModelK05

RMS (s)0.37

Mean (s)
0.01

W07

0.66

-0.03

W07

0.49

0.24
Lin et al. (2011)

Constraining Structure by Ground-Truth DataFirst-arrival times from four longprofiles and dense receivers innorthern Taiwan
10 Explosions
First-arrival picks: ~ 3400 (out of ~ 6000)

Shot Size
Date (GMT)CWB Longitude Latitude Elev.
Point (kg) dd/mm/yyyy hh:mm:ss.sss ML(GS84)(m)
S1 1000
S2750
S3500
S3P 1500
S4750

02/27/2008 17:01:49.486 3.02 120.238026 23.508864 602/27/2008 17:30:57.350 2.62 120.421259 23.423385 2002/26/2008 18:02:45.860 1.89 120.714736 23.280129 650
02/26/2008 17:32:43.290 1.78 120.626749 23.136994 335
02/28/2008 17:02:08.560 2.30 121.141722 23.132877 390

N1750
N2750
N3750
N3P 3000
N4 1000

03/06/2008 17:03:23.068 2.56 121.045868 24.793562 55
03/06/2008 17:34:56.364 1.55 121.235817 24.675632 590
03/04/2008 18:01:17.988 2.10 121.487867 24.576938 405
03/04/2008 17:01:17.824 2.67 121.487867 24.576938 405
03/05/2008 17:03:40.008 2.43 121.811684 24.446901 6

Near-Surface Wave Speed Estimation
Surface site classification from Lee & Tsai (2008)

Lin et al. (2011)

Geological Zonation of Taiwan

Pseudo-2D (P2D)
ModelCPWF

WCRLV&ECR CoR

Compilation of P2D Models

westComparison with
Tomography Models
ModelRMS(s)Perturbation (%)

P2D

0.13-61 ~ 42

K05

0.37

-10 ~ 10W07

0.41-10 ~ 10

KC120.56-15 ~ 25

CPeastWF

CRCoR

Comparison with
Tomography Models

southnorthQuantitative Comparison (4 Longer Profiles)
Models slower
than real EarthModels fasterthan real Earth

Mean (s)RMS (s)Variance (s2)P2D

-0.007

0.12

0.02

K05

-0.25

0.45

0.15

W07

0.02

0.45

0.20

KC120.34

0.47

0.11

Comparison in Northern Taiwan

Quantitative Comparison (Northern Taiwan)
Models slower
than real EarthModels fasterthan real Earth

Mean (s)RMS (s)Variance (s2)P2D

-0.007

0.10

0.01

K05

-0.15

0.43

0.16

W07

0.09

0.46

0.20

KC120.28

0.36

0.06

Partition Modelling Tomography in Northern Taiwan

1. The study region is partitioned by horizontal Voronoi cells.
2. The Voronoi cells are determined by randomly-generated control points (blackdots) with density based on distribution of P2D profiles.
3. The velocity in each cell is assumed homogeneous, with value determined bythe average of all the P2D profiles passing through the cell (red lines).

Stability Test
Depth= 0 km

RMS of ensemble average models
between 2 consecutive realizations

emble Average Model of Northern Taiwan

urface Wave Phase Velocity Tomography

SL01
SL06
SL14
SL21SL25

Model from Surface Wave Tomography
Surface Wave Tomography

SL01
SL06
SL14KC12 (Traveltime)
SL21
SL25

ure Direction: Finite-Frequency Approach
Numerical modeling of wavefield in 3D
structure with irregular geometry
Full-wave sensitivity kernels
Multi-scale, iterative inversions
Account for anelasticity effectsThank you!