# Site-Specific Spectra for the City of Mexicali, Mexico, Obtained from April 2010 Earthquake Records
## 3 Conclusions and Recommendations  
A spectral analysis was carried out using the seismic records of April 2010, Mw = 7.2, obtained in the region of Mexicali, B.C. Records from the nearest stations to the epicenter were considered for this study. In addition, information from a geotechnical profile obtained in the urban center of the city of Mexicali, B.C., was used. Due to the uniformity of the existing soil in this city, such geotechnical information can be considered representative of the area under study. With the main idea of reviewing the design spectrum currently used in the region [18], an equivalent linear method was used to propagate the site-corrected SH waves through the aforementioned geotechnical profile. Using the synthetic records obtained for the surface, the elastic response spectra at 5% damping were calculated for each station and compared with the local design spectrum [18].  
Figure 9: The 5% response spectra (colored lines) for each recording station and design spectrum (MOC-CFE).  
Based on our analysis, we suggest that the design spectrum of the CFE regulation can be considered a representative spectrum for the city of Mexicali for periods greater than 1.3 s (flexible structures) but probably not for short periods. The current design spectrum can be considered non-conservative for structures with vibration periods of 0.3 to 1.3 s.  
The design of new structures with a natural vibration period within this window must consider that the amplitudes established in the CFE regulation are not the maximum amplitudes that can occur. The design spectra have a smoother shape because they are obtained by considering aspects of regional tectonics, seismology, and seismic hazard rather than site-specific considerations.  
In this sense, it is essential to emphasize that the results obtained in this study were obtained from real data for this specific site.  
More site effect studies are needed in Mexicali. Dynamic amplification functions and soil mechanic studies should be performed all over the city to create a proper database, which is essential for any reliable building regulations.  
It is advisable to continuously update the MOC-CFE [18] with local data and contribute to increasing data collection, but more importantly, to creating official building regulations for the country's main cities.  
Conceptualization H.E.R.L., T.D.R. and A.A.-M.; methodology H.E.R.L., T.D.R., A.A.-M., M.E.T.S., A.G.-E. and J.H.-C.; validation M.E.T.S. and A.G.-E.; data curation, H.E.R.L. and J.H.-C.; writing--original draft preparation, H.E.R.L., T.D.R. and A.A.-M.; writing--review and editing, M.E.T.S., A.G.-E. and J.H.-C. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
We used public and private data. The main private data presented in this study are available on request from the corresponding author.  
The authors thank the CONAHCYT (Consejo Nacional de Humanidades, Ciencias y Tecnologias) for supporting the members of the SNII (Sistema Nacional de Investigadores e Investigadoras). They also thank their universities.  
The authors declare no conflicts of interest.