Gravity Lab: a research group within IGPP at the University of California, San Diego.
IGPP (the Institute of Geophysics and Planetary Physics) is a Research Division at SIO (Scripps Institution of Oceanography). SIO is a Department at UCSD (the University of California, San Diego). Our labs are situated in both the Revelle and Munk buildings of IGPP overlooking the Pacific Ocean.
Our research group develops geophysical instruments. Our name stems from our original focus as established 25 years ago, which was to study Earth's changing gravity field through absolute and relative measurements on land and on the seafloor. Gravity measurement remains an important component of our activities. A second research focus, on precision optical measurement of Earth phenomena, has resulted in new technologies with additional geophysical applications. These include sensors for detection of seismic, infrasonic, and crustal deformation signals. The Gravity Lab is headed by Dr. Mark Zumberge, who has been a Research Geophysicist and Lecturer at IGPP since 1982. He and two other research scientists, Drs. Glenn Sasagawa and Kris Walker, lead the lab and formulate our research priorities.
One method that we use to measure crustal deformation along the seafloor (where GPS surveys are difficult) is to monitor changes in the ambient seawater pressure, whose value is governed primarily by depth (pressure ~= rho*g*h, where rho is the seawater density, g is local gravity, and h is depth). Modern pressure gauges based on quartz technology (e.g., Paroscientific Digiquartz gauges) can detect the pressure shift associated with volcanic uplift of the seafloor of as little as 1 cm at the bottom of the deep ocean. However, all gauges undergo a slow drift, which can mimic the signal of a slowly inflating volcano and produce misleading data. To circumvent this problem, we have developed a system that periodically calibrates the pressure gauges in place on the seafloor. Details are on the Research page under "Self Calibrating Pressure Recorder." Click here for details. Revised: January 2012