Seafloor Seismographs Rapidly Deployed Following Major Earthquake Offshore Northern California
Within just 11 days of the earthquake—the fastest response in our program’s history—9 ocean bottom seismographs were deployed off the coast of Cape Medocino, California. These instruments complement about 115 nodes and 18 real-time aftershock stations deployed on land by the USGS Earthquake Hazards Program. Since the mainshock and most of the aftershocks are up to 43 miles (70 kilometers) offshore, combining ocean bottom seismograph data with the data collected on land should significantly improve fault zone imaging, as well as our understanding of aftershock locations and the velocity structure near the rupture zone. The team will return in 45
Rapid Response Seafloor Seismology
The new ocean-bottom seismographs record shaking with an accelerometer. Similar to the computer chips that measure motion in smartphones, this finger-nail-sized sensor can measure shaking in any orientation, removing the need for the large, complex, and power-consuming leveling systems used by traditional seafloor instruments. Combining the accelerometer with low-power recording electronics means the new instruments need less battery power, further reducing the size and weight of the instruments. The fleet currently has 10 instruments that measure 24 by 24 inches and weigh about 50 pounds. The instruments can be deployed for about 50 days in water up to ~4 miles