Spatiotemporal variations of characteristic repeating earthquake sequences along the Middle America Trench in Mexico

Abstract

Searching for repeating earthquakes allows the examination of spatiotemporal variation of slip budget in the subduction of the Cocos plate in the Guerrero‐Oaxaca region of Mexico. As different transient phenomena continuously load and unload stresses around asperities in an area where megathrust earthquakes nucleate, repeating earthquakes act as track markers for slip on the plate interface. We systematically examined 14 years of waveform records from 2001 through 2014 to identify repeating earthquakes along the subducting segment of the Cocos plate. An analysis of waveform similarity resulted in a significant number (224) of earthquake sequences with highly correlated waveforms (correlation coefficient cc ≥ 0.95 and spectral coherency coh ≥ 0.95). The reported set of correlated waveforms shows a well‐defined clustering in space and substantial temporal variability. We find a significant increase of repeating earthquake activity after the 20 March 2012 Ometepec (Mw 7.4) and 18 April 2014 Tecpan (Mw 7.2) earthquakes as a result of the postseismic relaxation. In contrast, the rupture zone of the 1985 (Mw 8.1) Michoacán earthquake is completely devoid of repeating sequences, suggesting a strongly coupled segment. Examining the temporal behavior of repeating earthquake activity provides a new tool to better understand how creeping of the subduction thrust controls stress release and postseismic relaxation.

Detection of repeating earthquakes and their application in characterizing slow fault slip

“…The scaling by Nadeau and Johnson (1998) suggests that T r ∝M 1=6 o , where T r represents the recurrence interval. This relationship is different from the generally accepted relationship T r ∝M 1=3 o which is derived from the standard assumption of constant stress drop (Nadeau and Johnson 1998) and discussed based on laboratory-derived friction laws (e.g., Chen and Lapusta 2009;Cattania and Segall 2018) and observations (Chen et al 2007;Yu 2013;Dominguez et al 2016). Chen et al (2007) showed that the T r −M o relationship holds not only in California but also in Taiwan and Japan when geodetically derived slip rates are adjusted.…”

Seismicity Controlled by a Frictional Afterslip During a Small‐Magnitude Seismic Sequence (ML < 5) on the Chihshang Fault, Taiwan

“…Therefore, some events may have escaped waveform detection or the recurrence interval of each sequence could be larger than the recurrence interval of the reported REs that ranges between 1 and 4 years (Chen et al, ). However, it has been shown that sequences of REs can also respond to nearby earthquakes with decreasing recurrence intervals (as burst‐type repeaters) that are gradually recovering to preseismic rate, consistent with their being controlled by afterslip (Dominguez et al, ; Lengline & Marsan, ; Schaff et al, ; Uchida et al, , ). This may suggest that the multiplets reported here, which occurred only during a few hours, have been activated by the afterslip (especially during stage A1) and therefore occurred exclusively during this sequence.…”

Emergence and disappearance of interplate repeating earthquakes following the 2011 M9.0 Tohoku‐oki earthquake: Slip behavior transition between seismic and aseismic depending on the loading rate

“…In the northeastern Japan subduction zone, some areas have been ruptured repeatedly by large interplate earthquakes, which can be interpreted as repeated ruptures of “asperities” or “seismic patches” on the plate boundary [e.g., Nagai et al , ; Yamanaka and Kikuchi , , ]. Besides large co‐located earthquakes, small repeating earthquake sequences (groups of earthquakes showing nearly identical waveforms) have been found in California [e.g., Ellsworth , ; Nadeau et al , ; Bürgmann et al , ; Peng et al , ], northeastern Japan [e.g., Matsuzawa et al , ; Igarashi et al , ; Matsubara et al , ; Kimura et al , ], Turkey [ Peng and Ben‐Zion , ; Schmittbuhl et al , ], Taiwan [ Rau et al , ; Chen et al , ], Tonga [ Yu , ], Mexico [ Dominguez et al , ] and so on. Such sequences can be interpreted as repeated ruptures of small isolated asperities surrounded by areas dominated by aseismic slip [e.g., Nadeau and Johnson , ; Sammis and Rice , ; Anooshehpoor and Brune , ; Beeler et al , ; Johnson and Nadeau , ].…”