Research
Asthenospheric and Lithospheric Broadband Architecture from the California Offshore Region Experiment (ALBACORE)
Objectives
The objective of the ALBACORE project is to understand the tectonic interaction at the Pacific-North America plate boundary by identifying the physical properties and deformation styles of the Pacific plate and nearshore microplates. The results will be used to distinguish among contrasting upper mantle geodynamic scenarios that predict large-scale mantle flow patterns beneath western North America. This will be accomplished through seismic studies using ocean bottom seismometer (OBS) array data.
The results will characterize the driving plate motion consequences of collision between the rift system, a fragmented subducted plate, the lengthening of the San Andreas transform fault system, and block rotations. The boundaries for the seismic array overlap the region of complex breakup and fracture of the Pacific plate near shore where several microplates are observed, and extend far to the west to provide comparison with oceanic lithosphere that is not fractured and has formed at a uniform rate. The results will aid in understanding the boundary forces due to relative plate motions, the driving forces and characteristics of oceanic and continental scale deformation, and how the continental margin accretionary process is influenced by offshore tectonics.
Experiment Design
- 12-month passive seismic experiment: August, 2010-September, 2011.
- 24 broadband OBSs (with differential pressure gauges) & 10 short-period OBSs (with high-frequency hydrophones) across southwestern half of Pacific-North America plate boundary.
- Collection of continuous, 50 sps, three-component waveform data.
- Concurrent collection of multibeam bathymetry, gravity, magnetic field, and sedimentary echosounder data
Analysis Projects
- Surface-wave dispersion and azimuthal anisotropy
- Teleseismic travel-time tomography
- SKS splitting measurements
- Ambient noise cross-correlation measurements.
- Local earthquake travel-time tomography and receiver functions
- Offshore seismicity patterns, relationship with faults, hypocenters and focal mechanisms
- Offshore-onshore model for tectonic evolution and lithosphere-asthenosphere seismic structure
- Modeling of 2011 Tohoku tsunami recorded on differential pressure gauges.
People
Monica Kohler, Department of Mechanical and Civil Engineering, Caltech
Dayanthie Weeraratne, Department of Geological Sciences, CSU Northridge
Related Links
U.S. National Ocean Bottom Seismograph Instrument Pool (OBSIP)
University-National Oceanographic Laboratory System (UNOLS)
Scripps Institute of Oceanography Ship Operations (SIO Ship Operations) and R/V Melville.
National Geophysical Data Center: Marine Geology and Geophysics (NGDC-MGG)
UTEP PACES Gravity and Magnetic Data Repository (UTEP DB)
USGS Woods Hole bathymetry/backscatter database (USGS Woods Hole bathym/backscatter)
CSU Monterey Bay multibeam database (CSUMB multibeam)
USGS S.P. Lee cruise grav and mag database ( S.P. Lee DB)
USGS National Archive of Marine Seismic Surveys database (USGS NAMSS)
GMT Supplemental Man pages (GMT Supplemental)
GMT Main Reference, Tuturial, and Manual Pages (GMT: select "DOCS" link)
MB-System manual (MB-System) (List of programs)
Southern California Earthquake Center (SCEC)
Southern California Earthquake Data Center (SCEDC)
Center for Engineering Strong Motion Data (CESMD)
Unix Tutorial (Unix)
Java Tutorial (Java)
Java Tutorial for kids (Java for tutorial for kids)
SAC Tutorial (SAC)
PQL II Tutorial (PQL II)
Funded by the National Science Foundation, Division of Ocean Sciences in the Geosciences Directorate
