<?xml version="1.0" encoding="ISO-8859-1"?><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<front>
<journal-meta>
<journal-id>0016-7169</journal-id>
<journal-title><![CDATA[Geofísica internacional]]></journal-title>
<abbrev-journal-title><![CDATA[Geofís. Intl]]></abbrev-journal-title>
<issn>0016-7169</issn>
<publisher>
<publisher-name><![CDATA[Universidad Nacional Autónoma de México, Instituto de Geofísica]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S0016-71692025000201509</article-id>
<article-id pub-id-type="doi">10.22201/igeof.2954436xe.2025.64.2.1817</article-id>
<title-group>
<article-title xml:lang="en"><![CDATA[Strong Ground Motion during the 8 September 2021 (Mw 7.0) Acapulco Earthquake: Rupture Directivity and its Effect on Simulated Motions in Mexico City from Postulated Mw 7.5 &#8211; 8.0 Earthquakes]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Arroyo]]></surname>
<given-names><![CDATA[Danny]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Singh]]></surname>
<given-names><![CDATA[Shri K]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Ordaz]]></surname>
<given-names><![CDATA[Mario]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Iglesias]]></surname>
<given-names><![CDATA[Arturo]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,Universidad Autónoma Metropolitana Departamento de Materiales ]]></institution>
<addr-line><![CDATA[Mexico City ]]></addr-line>
<country>Mexico</country>
</aff>
<aff id="Af2">
<institution><![CDATA[,Universidad Nacional Autónoma de México Instituto de Geofísica ]]></institution>
<addr-line><![CDATA[Mexico City ]]></addr-line>
<country>Mexico</country>
</aff>
<aff id="Af3">
<institution><![CDATA[,Universidad Nacional Autónoma de México Instituto de Ingeniería ]]></institution>
<addr-line><![CDATA[Mexico City ]]></addr-line>
<country>Mexico</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>06</month>
<year>2025</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>06</month>
<year>2025</year>
</pub-date>
<volume>64</volume>
<numero>2</numero>
<fpage>1509</fpage>
<lpage>1520</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S0016-71692025000201509&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S0016-71692025000201509&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S0016-71692025000201509&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="en"><p><![CDATA[Abstract The 8 September 2021, M7.0, earthquake occurred in the SE Guerrero seismic gap along the Mexican subduction zone, just below Acapulco. The earthquake was strongly felt in Acapulco with peak ground acceleration (PGA) exceeding 0.6 g at some sites. An analysis of seismograms and accelerograms reveals a strong azimuthal variation of the seismic intensities. Unusually large intensities are observed in the NE direction with respect to the regional ground motion prediction equation (GMPE). This is consistent with the reported rupture directivity towards NE inferred from the slip distribution on the fault obtained from the inversion of local strong motion data. Using recordings of the 2021 earthquake and five other Guerrero thrust events (5.8 &#8804; M &#8804;7.3) at CU as empirical Green's functions (EGFs), we simulate ground motions for postulated M 7.5, 7.7, and 8.0 earthquakes in the Guerrero seismic gap. The simulated motions strongly depend on the source directivity of the EGF. The largest and smallest synthesized motions occur when the 8 May and 10 May 2014 events are used as the EGFs, respectively. Directivity towards and away from CU during the 8 May and 10 May earthquakes. respectively, is well-documented in a previous study. Three of the six EGFs yield synthesized motions from a postulated M 8.0 earthquake that exceed, two EGFs produce motions which are smaller, and one EGF gives similar motions to those observed at CU during the devastating 1985 Michoacan earthquake. Under adverse directivity conditions, as observed during the 8 May 2014 earthquake, even an M 7.5 event in Guerrero seismic gap may produce motions similar to that recorded in 1985. This may have been the case during the 28 July 1957 (M.7.5) Guerrero earthquake, the third most damaging event in the history of Mexico City.]]></p></abstract>
<abstract abstract-type="short" xml:lang="es"><p><![CDATA[Resumen El 8 de septiembre de 2021 un sismo de magnitud M 7.0 ocurrió en la región SE del GAP de Guerrero en la zona de subducción de México justo bajo la Ciudad de Acapulco. El sismo se sintió fuertemente en Acapulco con una aceleración máxima del suelo mayor a 0.6 g en algunos sitios. El análisis detallado de los sismogramas y acelerogramas muestra una fuerte variación de la intensidad sísmica con respecto al azimut. Intensidades excepcionalmente altas, con respecto al modelo de atenuación regional, fueron observadas en dirección NE del epicentro, lo cual es consistente con la directividad en la ruptura hacia la dirección NE inferida de la distribución del deslizamiento en la falla calculada a partir de la inversión de los registros locales. Usando los registros del evento de 2021 y 5 eventos mas en Guerrero con M entre 5.8 y 7.3 medidos en la estación Ciudad Universitaria en la CDMX como funciones empíricas de Green (EFG) se simularon registros para eventos con magnitudes postuladas de 7.5, 7.7 y 8. La intensidad de los registros simulados depende fuertemente de la directividad en la ruptura de la EGF. Las mayores intensidades en las simulaciones se observaron en el caso de directividad en dirección de la CDMX (EGF del 8 de mayo de 2014) y las menores intensidades se observaron para directividad en dirección contraria a la CDMX (EGF 10 de mayo de 2014). Los análisis revelan que bajo condiciones adversas de directividad inclusive un sismo con M 7.5 en el Gap de Guerrero puede producir intensidades en la CDMX similares a las registradas durante el sismo del 19 de septiembre de 1985. Esto pudo ser lo que ocurrió durante el sismo del 28 de Julio de 1957 (M7.5) el cual ha sido el tercer sismo más destructivo en la historia de la CDMX.]]></p></abstract>
<kwd-group>
<kwd lng="en"><![CDATA[rupture directivity]]></kwd>
<kwd lng="en"><![CDATA[Mexico seismic gap]]></kwd>
<kwd lng="en"><![CDATA[strong ground motion records]]></kwd>
<kwd lng="en"><![CDATA[variability of seismic intensities]]></kwd>
<kwd lng="es"><![CDATA[efectos de directividad]]></kwd>
<kwd lng="es"><![CDATA[brecha sísmica de México]]></kwd>
<kwd lng="es"><![CDATA[registros de movimiento fuerte]]></kwd>
<kwd lng="es"><![CDATA[variabilidad de intensidades sísmicas]]></kwd>
</kwd-group>
</article-meta>
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