The press might have a long history of offering the public some pretty screwy analyses of recent earthquake activity, blowing things out of proportion and generally misunderstanding the fundamentals but today’s “Morning Edition of NPR: Can A Big Earthquake Trigger Another One?” knocks the ball out of the park!:
In this piece some tough, thought-provoking questions are asked with class:
1. If an earthquake hits nearby, do chances of another big earthquake occurring go up? Are Santiago and Tokyo now in more danger because big earthquakes “exported stress” to their area?
2. Can seismologists predict significant earthquakes more readily following a mainshock-aftershock sequence than before?
3. How closely tied together are fault systems? Will the fault completely unzip or will only a button pop off?
Back when I worked in Ecuador at the Tungurahua Volcano Observatory (OVT, IGEPN), I used to field a lot of questions from reporters about the current levels of earthquake and volcanic unrest. For the next time, I will have to remember the vivid language used by reporter Christopher Joyce for communicating tough concepts to the public. Aftershocks are “Quake death spasms” and earthquakes are sometimes like “one button on a shirt popping” when other times they “unzip”.
P.S. If you are keen to learn more about earthquakes triggered by other earthquakes, I recommend reading:
Hill, D.P. et al. (1993) Seismicity remotely triggered by the magnitude 7.3 Lander, California, Earthquake. Science 260: 1617-1623
King, G.C.P., Stein, R.S., Lin, J. (1994) Static Stress Changes and the Triggering of Earthquakes. Bull. Seis. Soc. Am. 84: 935-953
McNutt, S.R. (2005) Volcanic Seismology. Annu. Rev. Earth Planet. Sci. 32:480-481
Toda, S., Lin, J., Meghraoui, M., Stein, R.S. (2008) 12 May 2008 M = 7.9 Wenchuan, China, earthquake calculated to increase failure stress and seismicity rate on three major fault systems. Geophysical Research Letters 35: doi:10.1029/2008GL034903
West, M., Sánchez, J.J. and McNutt, S.R. (2010) Periodically triggered seismicity at Mount Wrangell, Alaska, after the Sumatra Earthquake. Science 308:1144-1146