The Log | School News

Ringside Seat on an Earthquake
Peter Malin's Team Monitored Parkfield's Magnitude 6 Temblor with Seven Seismometers

by Monte Basgall

For the past 20 years, Nicholas School geology professor Peter Malin had waited for a moderate earthquake along the San Andreas fault in the vicinity of Parkfield, Calif. This village bills itself as the “earthquake capitol of the world.” Through much effort, his seismology group had seven seismometers ready at a ringside seat about 3,000 feet underground when a magnitude 6 temblor finally hit Sept. 28, 2004.

The members of Malin’s laboratory had pre-positioned those recording instruments within the first leg of the ambitious San Andreas Fault Observatory at Depth (SAFOD) project near Parkfield. SAFOD’s goal is to drill an angled shaft into the notorious fault to create an unprecedented underground observation site for earthquakes.

As the Duke group’s seismographs began reacting to the quake, Malin’s senior graduate student Tom Taylor was on station in an instrument hut beside SAFOD’s initial pilot hole. Taylor jumped as he felt the first jolt, which was followed by a string of thumping aftershocks, some nearer and others farther away. What one of the Duke group’s instruments recorded later was converted into an audio record for Web browsers called “The Sounds of the Parkfield Earthquake” at www.cisn.org/ special/evt.04.09.28/sounds.html.

All of this was very good news, recalls Malin in an interview at his office in the Nicholas School’s Division of Earth and Ocean Sciences. But there was one bit of very bad luck, and several surprises too.

The biggest surprise was that the break in the fault line started from the opposite direction than scientists had expected. Experts thought that the fault would crack from the north of Parkfield, with the slip moving to the south. That was the pattern followed by predecessor magnitude 6 quakes in 1966, 1934 and 1922. Instead, this one began where those previous episodes ended, and then moved north from an underground locus about 20 kilometers to the south of Parkfield.

Geologists later pinpointed that kick-off point as near and below the place where actor James Dean died in 1955 in a sports car crash, noted California native Malin. In fact, the quake occurred just two days before the 49th anniversary of Dean’s death.

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