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2011 Guerrero earthquake

Coordinates: 16°48′29″N 98°35′31″E / 16.808°N 98.592°E / 16.808; 98.592
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2011 Guerrero earthquake
2011 Guerrero earthquake is located in Mexico
2011 Guerrero earthquake
Mexico City
Mexico City
Map showing the epicenter of the earthquake
UTC time??
Duration~1 minute[1]
Magnitude5.7 Mw[2]
Depth24 km (14.9 mi)
Epicenter16°48′29″N 98°35′31″E / 16.808°N 98.592°E / 16.808; 98.592
TypeInterplate
Areas affected Mexico
Total damageMinimal
Max. intensityMM VI[3][4]
Aftershocks5 (≤4.1 ML)[5]
CasualtiesNone reported

The 2011 Guerrero earthquake was a shallow magnitude 5.7 Mw earthquake that struck southern Mexico at 08:24 local time (13:24 UTC) on Thursday, 5 May 2011. It was positioned west of Ometepec, Guerrero at a depth of 24 km (14.9 mi), and was lightly felt in many adjacent areas. Buildings swayed with the tremor in Mexico City, prompting evacuations and causing panic among many. There were no immediate reports of casualties, though two local police stations suffered slight damage. In total, at least five light aftershocks were reported, with the strongest measuring a magnitude of 4.1 (ML).

Geology

The magnitude 5.7 (Mw) earthquake occurred inland near the south coast of Mexico at a depth of 24 km (14.9 mi), with a duration of nearly one minute and an epicenter about 55 km (34 mi) west of Ometepec, Guerrero.[1][6][2] In the region, the Cocos, North American, and Caribbean Plates converge and create a tectonic zone of continuous seismic activity.[7] The quake struck near the eastern periphery of the Guerrero seismic gap, which extends from Acapulco to Ixtapa–Zihuatanejo and contains enough stored energy to generate an earthquake of up to magnitude 7.5. Seismologists confirmed that the magnitude 5.7 tremor did not cause the gap to rupture, however.[8] Initial estimates from the USGS placed its intensity at a magnitude of 5.8 (Mw),[9] though the quake was measured at magnitude 5.5 (ML) by the Mexican National Seismological Centre.[10]

USGS shake map

Owing to the magnitude of the quake, significant shaking was only felt in localized parts of Costa Chica, registering strongest at VI (strong) on the Mercalli scale in Azoyú and V (moderate) in populous areas near the epicenter.[3] Lighter ground motion (MM III) was perceived in many areas including Acapulco and Chilpancingo, with weak tremors (MM II) even reported in Mexico City, about 300 km (187 mi) from the epicenter.[11][4] According to geophysicists, the city rests on a former lakebed of largely unconsolidated sedimentary layers; therefore, earthquake shaking in its vicinity is generally amplified.[11]

Aftershocks

By 6 May, a total of five light aftershocks were reported near the epicenter. Of the five, the first occurred at a magnitude of 3.7 (ML) about 15 minutes after the main shock, and was succeeded by a magnitude 3.9 (ML) tremor at 10:09 local time. Two similar quakes of minor intensity struck the region the next day; however, the strongest and final aftershock registered a magnitude of 4.1 (ML), and occurred at 04:00 in the morning.[5]

Impact and response

Despite relatively strong ground motions, damage to the area was very limited; structures around the epicenter were reported to be a mix of fairly vulnerable and resistant to earthquake shaking.[4] Buildings swayed with the tremor in Mexico City, causing panic among many and prompting some to evacuate.[12] Several schools in Guerrero were evacuated as a safety precaution.[1] The earthquake and its aftershock sequence contributed to intermittent power outages in Acapulco; more than 40,000 residences in some 40 districts were without power the next day.[13] There were no reports of major losses or fatalities in the wake of the tremor, though two police stations located in Acapulco and Marquelia suffered light damage.[14][15][12]

Prior to the arrival of seismic waves in Mexico City, a "potentially significant quake" was detected by seven of twelve earthquake sensors near the coast of Guerrero. Alert systems were subsequently activated in the area, giving locals at least 50 seconds to secure themselves.[16] Shortly after impact, authorities dispatched five helicopters to ascertain any damage in the wake of the quake.[17] SSP officials patrolled the city streets along with over 3000 police officers as a safety measure.[18] In response to its occurrence, the Federal District announced the installation of 50,000 seismic alarms in local schools, hospitals, and offices. Reassessments of structural conditions — particularly in earthquake-prone parts of the state — were scheduled, while some 1,817,000 government workers partook in an earthquake simulation exercise the following day.[19]

Scientific reaction

Though the intensity of the quake was fairly significant, specialists report that earthquakes of such magnitude do not release nearly enough seismic energy to prevent a major earthquake from occurring in the region. Cumulatively, an estimated 900 earthquakes of similar intensity are required per year to total the energy unleashed by a magnitude 7.5 earthquake. Many locals perceived an apparent increase in recent earthquake occurrences, though seismologists registered normal levels of seismic activity in the area.[20] In 2009, a similar magnitude 5.8 Mw earthquake struck Guerrero near Acapulco at a depth of 35 km (22 mi), killing at least two people.[21][22]

See also

References

  1. ^ a b c Template:Es icon Staff Writer (5 May, 2011). "Sacude sismo de 5.5 grados en la escala de Richter Ciudad de México; Saldo Blanco". veracruzanos.info. Noticias Veracruz. Retrieved 2011-05-07. {{cite web}}: Check date values in: |date= (help)
  2. ^ a b "Magnitude 5.7 Guerrero, Mexico". neic.usgs.gov. NEIC, USGS. 5 May, 2011. Retrieved 2011-05-05. {{cite web}}: Check date values in: |date= (help)
  3. ^ a b "Pager Version 3 – M 5.7, Guerrero, Mexico" (PDF). earthquake.usgs.gov. USGS. 5 May, 2011. Retrieved 2011-05-05. {{cite web}}: Check date values in: |date= (help)
  4. ^ a b c "Pager - M 5.7 – Guerrero, Mexico". earthquake.usgs.gov. USGS. 5 May, 2011. Retrieved 2011-05-05. {{cite web}}: Check date values in: |date= (help)
  5. ^ a b Template:Es icon "Ultimos sismos registrados". ssn.unam.mx. SSN. 5 May, 2011. Retrieved 2011-05-05. {{cite web}}: Check date values in: |date= (help)
  6. ^ EFE (5 May, 2011). "Strong earthquake rocks southern Mexico". latino.foxnews.com. Fox News Network. Retrieved 2011-05-05. {{cite web}}: Check date values in: |date= (help)
  7. ^ Template:Es icon Staff Writer (5 May, 2011). "México registra un sismo de 5.5 grados con epicentro en Guerrero". mexico.cnn.com. CNN México. Retrieved 2011-05-05. {{cite web}}: Check date values in: |date= (help)
  8. ^ Template:Es icon amd (5 May, 2011). "Ciudadanos deben estar preparados ante sismos: SSN". radioformula.com.mx. Grupo Fórmula. Retrieved 2011-05-06. {{cite web}}: Check date values in: |date= (help)
  9. ^ "Magnitude 5.8 Guerrero, Mexico". earthquake.usgs.gov. USGS. 5 May, 2011. Retrieved 2011-05-06. {{cite web}}: Check date values in: |date= (help)
  10. ^ Template:Es icon "Localización del sismo seleccionado: Magnitud 5.5". ssn.unam.mx. SSN. 5 May, 2011. Retrieved 2011-05-06. {{cite web}}: Check date values in: |date= (help)
  11. ^ a b AFP (5 May, 2011). "Mexico City rocked by 5.8 earthquake". news.yahoo.com. AlertNet. Retrieved 2011-05-06. {{cite web}}: Check date values in: |date= (help)
  12. ^ a b Associated Press (5 May, 2011). "Earthquake shakes wide area of southern Mexico". google.com. Desert News. Retrieved 2011-05-07. {{cite web}}: Check date values in: |date= (help)
  13. ^ Template:Es icon Sandoval, Adriana Covarrubias (6 May, 2011). "Sismos afectan alumbrado público de Acapulco". eluniversal.com.mx. El Universal. Retrieved 2011-05-07. {{cite web}}: Check date values in: |date= (help)
  14. ^ Template:Es icon Covarrubias, Adriana (5 May, 2011). "Sismo daña cuartel de policía de Acapulco". eluniversal.com.mx. El Universal. Retrieved 2011-05-07. {{cite web}}: Check date values in: |date= (help)
  15. ^ Template:Es icon Notimex (5 May, 2011). "Causa sismo cuarteaduras en sede policial en Guerrero". radioformula.com.mxn. Grupo Fórmula. Retrieved 2011-05-08. {{cite web}}: Check date values in: |date= (help)
  16. ^ Template:Es icon Miselem, Sofía (5 May, 2011). "Alerta sísmica en Ciudad de México: 50 segundos para ponerse a salvo". google.com. AFP. Retrieved 2011-05-07. {{cite web}}: Check date values in: |date= (help)
  17. ^ Template:Es icon Pantoja, Sara (5 May, 2011). "GDF reporta saldo blanco tras sismo de 5.5 grados". eluniversal.com.mx. El Universal. Retrieved 2011-05-07. {{cite web}}: Check date values in: |date= (help)
  18. ^ Template:Es icon EFE (5 May, 2011). "Sismo de 5.5 grados Richter en DF; epicentro en Guerrero". terra.com.mx. Terra. Retrieved 2011-05-22. {{cite web}}: Check date values in: |date= (help)
  19. ^ Template:Es icon Castillejos, Jessica (7 May, 2011). "Protección civil en el DF fortalecerá alerta sísmica". excelsior.com.mx. Excélsior. Retrieved 2011-05-07. {{cite web}}: Check date values in: |date= (help)
  20. ^ Template:Es icon Montes, Rafael/Marisol (6 May, 2011). ""Evitan minisismos un terremoto mayor"". eluniversal.com.mx. El Universal. Retrieved 2011-05-07. {{cite web}}: Check date values in: |date= (help)
  21. ^ USGS (27 April, 2009). "M5.8 – Guerrero, Mexico". Retrieved 2011-05-17. {{cite web}}: Check date values in: |date= (help)
  22. ^ Associated Press (27 April, 2009). "Earthquake shakes buildings in Mexico". foxnews.com. Fox News Network. Retrieved 2011-05-17. {{cite web}}: Check date values in: |date= (help)