Journal of Geophysical Research (Solid Earth), 2019
We use Coulomb stress change (CSC) analyses and seismicity data to model the physical and statist... more We use Coulomb stress change (CSC) analyses and seismicity data to model the physical and statistical behaviour of the multi-fault source of the 4th September 2010 Mw7.1 Darfield earthquake in New Zealand. Geodetic and seismologic data indicate this earthquake initiated on a severely-misoriented reverse fault and propagated across a structurally complex fault network including optimally-oriented faults. The observed rupture sequence is most successfully modelled if maximum CSC imposed by rupture of the hypocentral fault on to receiver faults exceeds theoretical threshold values of 1 to 5 MPa that are assigned based on fault slip tendency and stress drop analyses. CSC modelling using the same criteria but initiating the earthquake on other faults in the network results in a multi-fault rupture cascade for five of seven scenarios. Analysis of earthquake frequency-magnitude distributions indicate that a Gutenberg-Richter frequency-magnitude distribution for the near source region cannot be rejected in favour of a characteristic earthquake distribution. However, characteristic behaviour is more favoured probabilistically because ruptures initiating on individual source faults in the system are statistically more likely to cascade into multi-fault ruptures with larger amalgamated Mw (Mwmax = 7.1) than to remain confined to the hypocentral source fault (Mw = 6.3 to 6.8). Our favoured hypothesis is that system rupture behaviour is regulated by misoriented faults that occupy critical geometric positions within the network, as previously proposed for the 2010 El Mayor–Cucapah earthquake in Baja California. Other fault networks globally may exhibit similar physical and statistical behaviours.
Journal of Geophysical Research (Solid Earth), 2019
We use Coulomb stress change (CSC) analyses and seismicity data to model the physical and statist... more We use Coulomb stress change (CSC) analyses and seismicity data to model the physical and statistical behaviour of the multi-fault source of the 4th September 2010 Mw7.1 Darfield earthquake in New Zealand. Geodetic and seismologic data indicate this earthquake initiated on a severely-misoriented reverse fault and propagated across a structurally complex fault network including optimally-oriented faults. The observed rupture sequence is most successfully modelled if maximum CSC imposed by rupture of the hypocentral fault on to receiver faults exceeds theoretical threshold values of 1 to 5 MPa that are assigned based on fault slip tendency and stress drop analyses. CSC modelling using the same criteria but initiating the earthquake on other faults in the network results in a multi-fault rupture cascade for five of seven scenarios. Analysis of earthquake frequency-magnitude distributions indicate that a Gutenberg-Richter frequency-magnitude distribution for the near source region cannot be rejected in favour of a characteristic earthquake distribution. However, characteristic behaviour is more favoured probabilistically because ruptures initiating on individual source faults in the system are statistically more likely to cascade into multi-fault ruptures with larger amalgamated Mw (Mwmax = 7.1) than to remain confined to the hypocentral source fault (Mw = 6.3 to 6.8). Our favoured hypothesis is that system rupture behaviour is regulated by misoriented faults that occupy critical geometric positions within the network, as previously proposed for the 2010 El Mayor–Cucapah earthquake in Baja California. Other fault networks globally may exhibit similar physical and statistical behaviours.
Uploads
Papers by M. Quigley