Quakefinder Blog

Remembering the 1989 World Series Earthquake

On the 17th of October this year, the 23rd anniversary of the Loma Prieta earthquake passed. It was a major earthquake with a magnitude of 6.9 that was nationally televised during a World Series game between the two Bay Area teams, the Oakland Athletics and the San Francisco Giants. I wonder what must have been going through Tony La Russa’s mind this past week? He was in Candlestick Park when the temblor hit, on the field as the manager of the A’s. He retired in May, and this past October 17th, he was surely with the St Louis Cardinals, at least in sprit. Would his team be required again to set foot into earthquake country again? That depended on the games, and the answer is yes. They came back out here, and had to stay through the seventh game. With the San Francisco Giants again headed to the World Series, we all recall this nationally televised seismic event. What many of us also remember is that there was a sensor up in the Loma Prieta Mountains that recorded magnetic signal anomalies in the month preceding the earthquake. It was an induction coil magnetometer, and produced four different types of signal anomalies. The first began on September 12th, 1989. It has been characterized as warbling tone that was seen to vary in frequency between 0.05 and 0.2 Hertz. It increased in amplitude to a peak of about approximate 1.5 nano-Teslas and persisted until October 5th, when it disappeared and the second anomaly occurred, which was an increase in noise on the whole spectrum (0.001-15 Hertz). This increase was about 30x over the normal noise level and declined gradually up until the third signal anomaly started about three hours before the earthquake. This was very curious, a distinctive drop and recovery in the noise background happened in the 0.2 to 5.0 Hertz frequencies. The fourth anomaly was confined to 0.01 to 0.5 Hz, and was an exceptionally strong signal that built up until the moment the earthquake occurred. Unfortunately the recording device was destroyed by the earthquake, so here the signal ends. But the controversy was just getting started. Papers were published by the project’s lead researcher Dr. Tony Fraser-Smith and a number of others, and these have been argued over ever since. Some believe that electromagnetic emissions are a red herring, but fortunately not all. Celeste Ford and Tom Bleier founded QuakeFinder in 1999, and began deploying induction coil magnetometers at key seismic locations throughout California. In 2007 international deployments began, and QuakeFinder now operates a network of 115 sensors that collect and process this magnetic field data. This has been done by partnering with businesses (Stellar Solutions, PG&E, Telephonica Peru, Vodafone Chilie), government (NASA) and Foundations (Musk Foundation). So when we remember the World Series earthquake of October 17, 1989, we might someday look back on this as a watershed event. If the means of forecasting earthquakes becomes available on a worldwide basis, then lives can be saved even in Detroit!

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