Earthquake Preparedness Should Not Fluctuate on a Daily or Weekly Basis

Abstract

Operational earthquake forecasting (OEF) is the practice of continual updating and dissemination of physics‐based short‐term (days) probabilities for the occurrence of damaging earthquakes. Although fully appreciating the noble intention of OEF and the scientific merits of the seismicity analyses it employs, we are concerned that its wide promotion may lead the public to believe that earthquake preparedness can fluctuate at timescales of days or weeks. Scientists who support OEF do recognize the importance of long‐term (decades and centuries) forecast. Jordan (2013) points out that long‐term forecasting can “guide earthquake safety provisions of building codes, performance‐based seismic design, and other risk‐reducing engineering practices, such as retrofitting to correct design flaws in older buildings.” However, they also believe that “properly done, short‐term forecasting complements long‐term seismic‐hazard analysis in promoting earthquake preparedness” and that “the age of OEF has arrived” (Jordan, 2013). Although to some extent short‐term forecasting is a worthwhile research subject, we question the claim that it should and can be made operational. A typical OEF warning would announce that the probability of an earthquake of certain magnitude happening in a given region over the next few days has increased from negligibly small values (such as 0.001%) to a larger value (such as 5%; Jordan and Jones, 2010). The probability gain of several orders of magnitude is thought to be useful for communicating risk to the public and enhancing preparedness. We have two concerns over this type of warning. First, warnings of this type send and reinforce a wrong message, that is, if scientifically estimated probability is very low, such as 0.001%, the public can afford to be less prepared for damaging earthquakes. OEF is based largely on analyses of earthquake clustering, or potential foreshock sequences, but the majority of damaging earthquakes are not preceded by …