Bulletin of the Seismological Society of America, 91, 5, pp. 1383, October 2001

Data Files from “The Importance of the Dynamic Source Effects on Strong
Ground Motion during the 1999 Chi-Chi, Taiwan, Earthquake: Brief
Interpretation of the Damage Distribution on Buildings”
by Luis A. Dalguer, K. Irikura, J. D. Riera, and H. C. Chiu

Introduction
We studied the effects of the dynamic rupture process
on ground motion of the 1999 Chi-Chi (Taiwan) earthquake.
For this purpose, the causative fault of the earthquake wasdivided in two vertical cross sections. These sections werechosen to represent the epicentral area (southern model) andthe northern part (northern model) of the fault. Each section
was modeled independently by using a 2D discrete element
model (DEM). In order to study the effects of the faulting
when the rupture does not break the surface, the southernmodel was used forcing the rupture process to stop 3 km
before reach the surface.
The output of the program for these three models isstored in ASCII format. The data consist of the distributionof the slip and slip velocity along the fault and the displacements and velocities along the free surface. These data wereused to plot all the figures in our article in this issue. Theobserved records used for comparison were provided by theSeismology Center, Central Weather Bureau (CWB), Taipei,Taiwan, distributed on CD-ROM in December 1999.
The archived data files are given on the attached CDROM, under the directory of \DalguerLA. In addition to areadme.txt file (this short note) and Figure1.pdf, there arethree sets of six compressed ASCII data files with filenamein the form: (1) velsurf.xxx: velocity distribution on the freesurface; (2) dissurf.xxx: displacement distribution on thefree surface; (3) sliphang.xxx: slip along the fault on thehanging-wall side; (4) slipfoot.xxx: slip along the fault on
the footwall side; (5) slvehang.xxx: slip velocity along thefault on the hanging-wall side; and (6) slvefoot.xxx: slip
velocity along the fault on the footwall side. “xxx” is “nor”
for the Northern model, “xxx” is “sou” for the Southernmodel, and “xxx” is “so1” for the model that does not breakthe free surface.

Explanation of the Data Files
The data in the files are in columns separated by acomma. The first column is the time (200 samples per sec).
The other columns correspond to displacement (m) or ve-locity (m/sec), depending on the file, of each point on thefault or free surface.
The slip and slip velocity are recorded in columns (afterthe time column) starting from the deepest part of the fault
and spaced every 0.25 km (161 columns plus the time column), except the files of the northern zone in which thecolumns are distributed every 0.5 km (81 columns plus thetime column), so the last column corresponds to the intersection with the free-surface (see Figure1.pdf on the attachedCD-ROM)
Displacements and velocities on the free surface are recorded in columns (after the time column) starting frompoint 1 on the hanging wall, 23.4 km from the trace of thefault (see Figure1.pdf on the attached CD-ROM). Each point
has two columns corresponding to the X and Y components,
respectively (X, perpendicular to the fault; Y, parallel to thefault). The points are spaced every 0.9 km from 1 to 27
corresponding to the hanging wall and from 28 to 54 corresponding to the footwall (108 columns plus the time column). Therefore, if we want to calculate the vertical andhorizontal components for each point, we need to do thecorresponding transformation of coordinates, as follows:
Horizontal ⳱ X sin(dip) ⳮ Y cos(dip),
Vertical ⳱ X cos(dip) Ⳮ Y sin(dip),
where dip is the dip angle of the fault assumed 33⬚ and 41
min.
Disaster Prevention Research InstituteKyoto University
Gokasho, Uji, Kyoto 611–0011, Japan(L.A.D., K.I.)
Federal University of Rio Grande do Sul
CPGEC
Porto Alegre, RS, Brazil(J.D.R.)
Institute of Earth Science
Academia Sinica
Nankang, Taipei, Taiwan(H.C.C.)1383