Delayed Dynamic Triggered Seismicity in Northern Baja California, México Caused by Large and Remote Earthquakes

Abstract

We analyze the seismicity in northern Baja California, Mexico, that

Nucleation speed limit on remote fluid-induced earthquakes

“…Their rates rise sharply and then decay over time like aftershocks, although they occur without a local mainshock. These examples demonstrate a globally observed tendency (5,(18)(19)(20)(21)(22) for remotely triggered sequences to be deficient in higher-magnitude earthquakes during the first 24 hours (or longer) as compared with local aftershocks (Fig. 1), which may be a result of comparatively smaller numbers of remotely triggered events or because of a physical process.…”

“…We are primarily interested in learning more about the largest remotely triggered earthquakes because they are the most dangerous. Indications from past studies suggest that these largest events happen but that they are often delayed relative to the arrival of surface waves (18)(19)(20)(21)(22). We begin by carefully examining the earliest observed events in the population of remotely triggered earthquakes as a function of their magnitudes to establish if there are any consistent patterns.…”

“…Intuitively, we would anticipate triggering to occur during this transient period, and many times, this is what happens (3). However, observations show that many dynamically triggered earthquakes do not initiate immediately but are instead delayed by hours or days following the passage of surface waves, an effect that is easiest to see among the largest remotely triggered earthquakes (18)(19)(20)(21)(22) because background rates of small earthquakes are the highest. Delayed remote earthquake triggering may be caused by surface waves that circle the globe more than once (23), by waves that jostle and change frictional properties in a fault zone (24) that causes delayed nucleation (25), or by a process where waves shake open (26) a fluid pressure valve (27) that unlocks a fault.…”

Observations of remotely triggered seismicity in Salton Sea and Coso geothermal regions, Southern California, USA, after big (MW>7.8) teleseismic earthquakes

“…They observed that the largest earthquake triggered (M L 3.5) occurred during the passage of the Love-wave peak amplitude. The Chile M w 8.8 earthquake also triggered seismicity in the El Mayor-Cucapah fault, Baja California region, Mexico, where the seismicity increased 10-20 days after this earthquake (Castro et al, 2015).…”