Dear Colleagues:

Reports on the Chi-Chi (Taiwan) earthquake of Sept. 21, 1999 (local time) are being prepared by W. H. K. Lee and associates on a temporary basis. Reports (and the associated data files available for download) posted on the Web site with the CWB logo had been approved for release by the Central Weather Bureau (CWB). We request that users of these CWB data acknowledge the data source as Seismology Center, Central Weather Bureau, Taipei, Taiwan, and reference the appropriate Report number.

These reports are very preliminary as thorough review and analysis of the data can not be performed within such a short time. However, the need for scientific study of this tragic earthquake calls for rapid release of relevant scientific data, especially given that this earthquake occurred shortly after an extensive seismic instrumentation program in Taiwan was completed in 1996. More than 1,000 modern digital accelerographs were installed by CWB at the free-field sites, in buildings, and on bridges.

CWB is the official agency for monitoring earthquakes in the Taiwan region. Seismic monitoring is being carried out by the staff of about 30 dedicated members of its Seismology Center, under the direction of Dr. K. W. Kuo, supervised by Dr. T. C. Shin, Deputy Director-General, and Mr. S. L. Hsieh, Director-General.

I am very grateful to CWB for supplying me some examples of their seismic data for review, and for allowing me to post some examples on the Web. I made arrangements with the Incorporated Research Institutions for Seismology (IRIS) and the United States Geological Survey (USGS) so that relevant information are available at: http://www.iris.washington.edu/news/events/taiwan/taiwan99.htm under the CWB/USGS item of the "Taiwan Sites", and at: http://caldera.wr.usgs.gov

So far, the two examples of waveform data posted on the Web site represents a tiny fraction of the recorded data. These arrangements were taken by me as a temporary measure to help CWB until they return to normal operations. CWB is now in the process of establishing a procedure for data release. I hope that a satisfactory solution will be found soon, so that these temporary reports will no longer be necessary. At this point, we will inform you where to go to obtain additional data.

List of Reports Released:

Report #1: 2 pages of general information; released, 6 a.m., Sept. 22, 1999.

Report #2: 8 pages of information on the mainshock and early aftershocks, and plots of two near source accelerograms; released, 12 p.m., Sept. 22, 1999.

Report #3: 2 pages on the two examples of near-source accelerograms with their uncorrected waveform data (as ASCII digital files) available for download; released, 9 a.m., Sept. 27, 1999.

Acknowledgements:
I wish to thank Dr. K. W. Kuo and his staff for supplying some examples of their seismic data for review and release. I would also like to thank Debbie Barnes and Mike Diggles, webmaster of the IRIS and of the USGS site, respectively.