Bulletin of the Seismological Society of America
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Bulletin of the Seismological Society of America; February 2006; v. 96; no. 1; p. 176-187; DOI: 10.1785/0120050001
© 2006 Seismological Society of America
This Article
Right arrow Abstract Freely available
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via ISI Web of Science (1)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Singh, S. K.
Right arrow Articles by Iglesias, A.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation

An Estimate of Shear-Wave Q of the Mantle Wedge in Mexico

S. K. Singh1, J. F. Pacheco1, D. García2 and A. Iglesias3

1 Instituto de Geofisica
Universidad Nacional Autónoma de México
Del. Coyoacán, C.P. 04510
Mexico, D.F.
 (S.K.S., J.F.P.)

2 Departmento Geofisica y Meteorología
Facultad de Ciencias Físicas
Universidad Complutense de Madrid
Av. Ciudad Universitaria
28040 Madrid, Spain
 (D.G.)

3 Instituto de Ingeniería
Universidad Nacional Autonóma de México
Del. Coyoacán, C.P. 04510
Mexico, D.F.
 (A.I.)


Figure 001
View larger version (65K):
[in this window]
[in a new window]

  		Figure 1. Map showing locations and focal mechanisms of the earthquakes analyzed in this study. Gray zone delineates Mexican Volcanic Belt. Isodepth contours of the Benioff zone (modified from Singh and Mortera, 1991; Pardo and Suarez, 1995) are marked (dashed where inferred). LVIG and PNIG are seismic stations at Laguna Verde nuclear power plant and Pinotepa Nacional, respectively. Seismograms from TUIG, located on a noisy site, are not used in the analysis. SCIG recorded only three of the events listed in Table 1. A to D refer to the four groups into which the events have been divided. Straight dashed lines, denoted A to D, from the trench to LVIG indicate the locations of the vertical sections on which the events are projected in Figure 4.

 

Figure 002
View larger version (28K):
[in this window]
[in a new window]

  		Figure 2. The distance coverage of the data available for events of groups A to D. For each event the source spectra retrieved from LVIG and, if available, from PNIG (marked by filled circles and triangles, respectively) are compared with the median spectrum obtained from all other stations of Mexican seismological and accelerometric stations (shown by open circles). Group A and C events provide an estimate of Q of the mantle wedge. Station SCIG is marked by filled rectangles in the figure.

 

Figure 003
View larger version (96K):
[in this window]
[in a new window]

  		Figure 3. (Top) Paths of inslab events used by García et al. (2004) to estimate Q and source spectra. Only 5 of the 268 records used in the study were from LVIG. Dots, earthquakes; triangles, stations. (Bottom) Paths of events included in the present study but not in García et al. (2004). The median spectra of these events were computed excluding data from LVIG and SCIG and are not appreciably affected by paths through the wedge.

 

Figure 004
View larger version (41K):
[in this window]
[in a new window]

  		Figure 4. Projection of the events of each group on a vertical plane extending from the trench to the station LVIG (see Fig. 1). All events are located either in the subducted slab or on the plate interface. For some events the plots do not show this. This is because the events are projected on sections that are not normal to the trench and the isodepth contours of the Benioff zone. Open circles, normal fault; filled circles, reverse fault.

 

Figure 005
Figure 005
View larger version (83K):
[in this window]
[in a new window]

  		Figure 5. The source spectrum obtained from the LVIG recording alone (continuous curve), and the median and ±one standard deviation source spectra (dashed curves) for the three events of group A. Dotted curves show source spectra retrieved from station PNIG. Left frames, all data corrected with Q(f) = 251f0.58; right frames, recordings at LVIG corrected with different Q(f) (given in the frames), for all other stations Q(f) = 251f0.58.

 

Figure 006
View larger version (35K):
[in this window]
[in a new window]

  		Figure 6. The source spectrum obtained from the LVIG recording alone (continuous curve), and the median and ±one standard deviation source spectra (dashed curves) for the events of group B. Dotted curves show source spectra retrieved from station PNIG. Note that a PNIG recording is not available for all events. Q(f) = 273f0.66 for the interplate B5 event; for all others events Q(f)=251f0.58.

 

Figure 007
View larger version (44K):
[in this window]
[in a new window]

  		Figure 7. Same as Figure 5 but for group C events.

 

Figure 008
View larger version (45K):
[in this window]
[in a new window]

  		Figure 8. Same as Figure 6 but for group D events. Here Q(f) = 273f0.66 for event D3, which is an interplate earthquake. For all other events Q(f) = 251f0.58.

 

Figure 009
View larger version (34K):
[in this window]
[in a new window]

  		Figure 9. Residual Amax as a function of the hypocentral distance for events of the four groups. Stations LVIG and PNIG are marked by filled circles and triangles, respectively.

 

Figure 010
View larger version (17K):
[in this window]
[in a new window]

  		Figure 10. Horizontal-to-vertical spectral ratio of S-wave group at LVIG, PNIG, and SCIG as function of frequency. Median and ± one standard deviation curves are shown.

 




HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2006 by the Seismological Society of America.