Reassessing the 2006 Guerrero slow-slip event, Mexico: Implications for large earthquakes in the Guerrero Gap

• Published in: Journal of geophysical research. Solid earth 2015-02, Vol.120 (2), p.1357-1375
• Main Authors: Bekaert, D. P. S., Hooper, A., Wright, T. J.
• Format: Article
• Language: English
• Subjects: Correlation; Earthquakes; Equivalence; Geological hazards; Geophysics; Global navigation satellite system; GPS; Guerrero; hazard; InSAR; Interferometric synthetic aperture radar; Interferometry; Navigation; Navigation satellites; Navigation systems; Radar; Rupture; Rupturing; SAR (radar); Satellites; Seismic activity; Seismic hazard; Seismic phenomena; Slip; slip deficit; slow slip; Spatial discrimination; Spatial resolution; Stresses; Synthetic aperture radar; Velocity
• ISSN: 2169-9313; 2169-9356
• DOI: 10.1002/2014JB011557

In Guerrero, Mexico, slow‐slip events have been observed in a seismic gap, where no earthquakes have occurred since 1911. A rupture of the entire gap today could result in a Mw 8.2–8.4 earthquake. However, it remains unclear how slow‐slip events change the stress field in the Guerrero seismic region and what their implications are for devastating earthquakes. Most earlier studies have relied on a sparse network of Global Navigation Satellite Systems measurements. Here we show that interferometric synthetic aperture radar can be used to improve the spatial resolution. We find that slip due to the 2006 slow‐slip event enters the seismogenic zone and the Guerrero Gap, with ∼5 cm slip reaching depths as shallow as 12 km. We show that slow slip is correlated with a highly coupled region and estimate that slow‐slip events have decreased the total accumulated moment since the end of the 2001/2002 slow‐slip event (4.7 years) by ∼50%. Nevertheless, even accounting for slow slip, the moment deficit in the Guerrero Gap increases each year by Mw∼6.8. The Guerrero Gap therefore still has the potential for a large earthquake, with a slip deficit equivalent to Mw∼8.15 accumulated over the last century. Correlation between the slow‐slip region and nonvolcanic tremor, and between slow slip and an ultraslow velocity layer, supports the hypothesis of a common source potentially related to high pore pressures. Key Points Slow slip entered the Guerrero seismic gap in 2006 The Guerrero Gap accumulated a Mw 8 equivalent slip deficit since 1911 The 2014 Guerrero earthquakes did not decrease the seismic hazard for Mexico City