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. Last Updated: 07/27/2016

Seismologically, 1999 Was Slow Year for Big Quakes




If there has been a certain apocalyptic feeling to the spate of recent earthquake activity worldwide, rest assured, it sometimes feels that way to the earth sciences community as well. While earth scientists don't see recent worldwide activity as a biblical harbinger, they are reeling from having to deal with the scientific and media response to five significant earthquakes - in Taiwan, Mexico, California and two in Turkey - in such close succession.


But the world is not coming to an end. The Earth has been around for a few billion years and doesn't care that, according to a modern calendar, we're about to click over to a nice, round number. In fact, globally speaking, 1999 is shaping up to be a slow year for earthquakes. While in an average year the planet experiences 15 to 20 events of magnitude 7.0 or greater, we have seen only eight so far in 1999. (Besides the places already mentioned, there were three M7-plus events in remote regions of the South Pacific.)


Recent activity is somewhat unusual in that so many of the 7.0-plus earthquakes have struck near populated areas, but we know this is only a matter of statistics. And as the global population surpasses 6 billion, the odds can only continue to worsen against us. Along the Pacific Rim, the so-called "ring of fire," virtually all major cities are vulnerable to earthquakes of 7.0 or more. That includes Los Angeles, Seattle and Anchorage, Alaska, in the United States as well as cities in all of Japan and the west coast of South America.


In California, the San Andreas fault has been considered "10 months pregnant" for a long time, and earth scientists have been monitoring a series of small earthquakes near the southern end that seem to have been triggered by the Oct. 16 earthquake in the desert near Barstow, known as the Hector Mine quake. The chance of a subsequent large earthquake still is considered low, but, at the same time, you don't have to be a seismologist to know that one can't stay 10 months pregnant forever.


Fortunately, where earthquakes and earthquake hazard are concerned, the new millennium is heralding tremendous opportunities as well as tremendous challenges. The 7.1 Hector Mine earthquake has been dubbed the first "cyberquake" because it is the first substantial earthquake to have struck southern California since the installation of the new, state-of-the-art "Trinet" seismic network. A collaborative effort among the U.S. Geological Survey, the California Institute of Technology and the California Divisions of Mines and Geology, Trinet provides more, better and faster seismic data than ever before.


A second important new instrumental initiative in southern California - by the Southern California Earthquake Center, the National Aeronautics and Space Administration and the USGS - involves installation of stations to record data from global positioning satellites tracking the slow, steady motion of the Earth's tectonic plates.


Yet earthquake hazard is, of course, by no means restricted to southern California. If the next big earthquake strikes too soon in northern California or elsewhere, scientists there will have far fewer integrated scientific/cyber-tools at their disposal.


Earthquakes aren't happening because a new millennium is nigh, but, much as we might wish otherwise, they won't stop happening, either.