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properties and investigate soil-structure interactions. These
vibrators also have been used in collaborative geophysical
investigations as sources for studies of deep basin structure.
Over the last few years, several experiments have been conducted
combining the NEES vibrators and sensors from the
PASSCAL pool. In these experiments the PIs make the initial
arrangements for the experiment while PASSCAL and NEES
staff coordinate scheduling and technical arrangements.
Figure 34. NEES vibrator deployed with PASSCAL multichannel
systems in Garner Valley, California (Photo c/o Jamie Steidl, UCSB)
Ocean Bottom Seismograph Instrument Pool (OBSIP)
OBSIP is analogous to PASSCAL in that it is a multi-user
pool of seismological instruments made available to the
research community. In the case of OBSIP, instruments are
funded through the NSF Division of Ocean Sciences and are
designed to operate autonomously on the ocean floor. Some
OBSIP experiments are carried out in remote ocean basins
and rely solely on ocean bottom instruments. Experiments
involving interactions with PASSCAL, include active-source,
onshore-offshore experiments (often coupled with air guns
and hydrophone streamers), and long-term deployments for
earthquake and structure studies at continental margins and
oceanic islands.
Because of complex logistics and the high cost of ship time,
the PASSCAL and OBSIP groups work closely together to
schedule joint experiments. One of the OBSIP PIs (John
Collins) was recently a member of the PASSCAL Standing
Committee. Although no longer a voting member, Dr. Collins
continues to attend meetings and otherwise advise PASSCAL.
The PASSCAL Program Manager is a member of the OBSIP
Oversight Committee and regularly communicates with
OBSIP operations. The PASSCAL Instrument Request Form
flags experiments proposing use of equipment from both the
PASSCAL and OBSIP facility. This additional alert ensures
that schedulers become aware of the need to coordinate at
the earliest opportunity. In addition to interactions with IRIS
related to PASSCAL instrumentation, OBSIP facilities also
arrange for all OBSIP data to be archived at the IRIS DMC.
University-National Oceanographic
Laboratory System (UNOLS)
UNOLS is responsible for coordinating activities of the
academic research fleet used in most NSF experiments in
ocean sciences. UNOLS also sets schedules for vessels used
in marine geophysical studies, including those involving
PASSCAL instruments. Staff from OBSIP and PASSCAL staff
attend scheduling meetings for the UNOLS ships and work
to identify and resolve potential problems associated with
coordinating instrument and ship schedules.
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