In a United States Geological Survey (USGS) study, preliminary rupture models of the earthquake indicated displacement of up to 9 meters along a fault approximately 240 km long by 20 km deep. The earthquake generated deformations of the surface greater than 3 meters and increased the stress (and probability of occurrence of future events) at the northeastern and southwestern ends of the fault. On May 20, USGS seismologist <answer>Tom Parsons</answer> warned that there is "high risk" of a major M>7 aftershock over the next weeks or months.
Who warned of possible seismic activity in the area beforehand?
Tom Parsons