Observations of changes in waveform character induced by the 1999 M w7.6 Chi-Chi earthquake

Kate Huihsuan Chen, Takashi Furumura, Justin Rubinstein, Ruey-Juin Rau

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

We observe changes in the waveforms of repeating earthquakes in eastern Taiwan following the 1999 Mw7.6 Chi-Chi earthquake, while their recurrence intervals appear to be unaffected. There is a clear reduction in waveform similarity and velocity changes indicated by delayed phases at the time of the Chi-Chi event. These changes are limited to stations in and paths that cross the 70 × 100 km region surrounding the Chi-Chi source area, the area where seismic intensity and co-seismic surface displacements were largest. This suggests that damage at the near-surface is responsible for the observed waveform changes. Delays are largest in the late S-wave coda, reaching approximately 120 ms. This corresponds to a path averaged S wave velocity reduction of approximately 1%. There is also evidence that damage in the fault-zone caused changes in waveform character at sites in the footwall, where source-receiver paths propagate either along or across the rupture. The reduction in waveform similarity persists through the most recent repeating event in our study (November 15, 2007), indicating that the subsurface damage induced by the Chi-Chi earthquake did not fully heal within the first 8 years following the Chi-Chi earthquake.

Original languageEnglish
Article numberL23302
JournalGeophysical Research Letters
Volume38
Issue number23
DOIs
Publication statusPublished - 2011 Dec 1

Fingerprint

waveforms
earthquakes
earthquake
damage
S-wave
Chi-Chi earthquake 1999
coda
recurrence interval
S waves
footwall
wave velocity
rupture
fault zone
Taiwan
receivers
stations
intervals
station

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Earth and Planetary Sciences(all)

Cite this

Chen, Kate Huihsuan ; Furumura, Takashi ; Rubinstein, Justin ; Rau, Ruey-Juin. / Observations of changes in waveform character induced by the 1999 M w7.6 Chi-Chi earthquake. In: Geophysical Research Letters. 2011 ; Vol. 38, No. 23.
@article{681805371df74567b375d85e538d93f6,
title = "Observations of changes in waveform character induced by the 1999 M w7.6 Chi-Chi earthquake",
abstract = "We observe changes in the waveforms of repeating earthquakes in eastern Taiwan following the 1999 Mw7.6 Chi-Chi earthquake, while their recurrence intervals appear to be unaffected. There is a clear reduction in waveform similarity and velocity changes indicated by delayed phases at the time of the Chi-Chi event. These changes are limited to stations in and paths that cross the 70 × 100 km region surrounding the Chi-Chi source area, the area where seismic intensity and co-seismic surface displacements were largest. This suggests that damage at the near-surface is responsible for the observed waveform changes. Delays are largest in the late S-wave coda, reaching approximately 120 ms. This corresponds to a path averaged S wave velocity reduction of approximately 1{\%}. There is also evidence that damage in the fault-zone caused changes in waveform character at sites in the footwall, where source-receiver paths propagate either along or across the rupture. The reduction in waveform similarity persists through the most recent repeating event in our study (November 15, 2007), indicating that the subsurface damage induced by the Chi-Chi earthquake did not fully heal within the first 8 years following the Chi-Chi earthquake.",
author = "Chen, {Kate Huihsuan} and Takashi Furumura and Justin Rubinstein and Ruey-Juin Rau",
year = "2011",
month = "12",
day = "1",
doi = "10.1029/2011GL049841",
language = "English",
volume = "38",
journal = "Geophysical Research Letters",
issn = "0094-8276",
publisher = "American Geophysical Union",
number = "23",

}

Observations of changes in waveform character induced by the 1999 M w7.6 Chi-Chi earthquake. / Chen, Kate Huihsuan; Furumura, Takashi; Rubinstein, Justin; Rau, Ruey-Juin.

In: Geophysical Research Letters, Vol. 38, No. 23, L23302, 01.12.2011.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Observations of changes in waveform character induced by the 1999 M w7.6 Chi-Chi earthquake

AU - Chen, Kate Huihsuan

AU - Furumura, Takashi

AU - Rubinstein, Justin

AU - Rau, Ruey-Juin

PY - 2011/12/1

Y1 - 2011/12/1

N2 - We observe changes in the waveforms of repeating earthquakes in eastern Taiwan following the 1999 Mw7.6 Chi-Chi earthquake, while their recurrence intervals appear to be unaffected. There is a clear reduction in waveform similarity and velocity changes indicated by delayed phases at the time of the Chi-Chi event. These changes are limited to stations in and paths that cross the 70 × 100 km region surrounding the Chi-Chi source area, the area where seismic intensity and co-seismic surface displacements were largest. This suggests that damage at the near-surface is responsible for the observed waveform changes. Delays are largest in the late S-wave coda, reaching approximately 120 ms. This corresponds to a path averaged S wave velocity reduction of approximately 1%. There is also evidence that damage in the fault-zone caused changes in waveform character at sites in the footwall, where source-receiver paths propagate either along or across the rupture. The reduction in waveform similarity persists through the most recent repeating event in our study (November 15, 2007), indicating that the subsurface damage induced by the Chi-Chi earthquake did not fully heal within the first 8 years following the Chi-Chi earthquake.

AB - We observe changes in the waveforms of repeating earthquakes in eastern Taiwan following the 1999 Mw7.6 Chi-Chi earthquake, while their recurrence intervals appear to be unaffected. There is a clear reduction in waveform similarity and velocity changes indicated by delayed phases at the time of the Chi-Chi event. These changes are limited to stations in and paths that cross the 70 × 100 km region surrounding the Chi-Chi source area, the area where seismic intensity and co-seismic surface displacements were largest. This suggests that damage at the near-surface is responsible for the observed waveform changes. Delays are largest in the late S-wave coda, reaching approximately 120 ms. This corresponds to a path averaged S wave velocity reduction of approximately 1%. There is also evidence that damage in the fault-zone caused changes in waveform character at sites in the footwall, where source-receiver paths propagate either along or across the rupture. The reduction in waveform similarity persists through the most recent repeating event in our study (November 15, 2007), indicating that the subsurface damage induced by the Chi-Chi earthquake did not fully heal within the first 8 years following the Chi-Chi earthquake.

UR - http://www.scopus.com/inward/record.url?scp=82955189791&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=82955189791&partnerID=8YFLogxK

U2 - 10.1029/2011GL049841

DO - 10.1029/2011GL049841

M3 - Article

AN - SCOPUS:82955189791

VL - 38

JO - Geophysical Research Letters

JF - Geophysical Research Letters

SN - 0094-8276

IS - 23

M1 - L23302

ER -