***UPDATE: CASCADIA RESTRICTION AND DATA RELOAD*** (see below)
The Cascadia Intitiative is an onshore/offshore seismic and geodetic experiment deployed in the Pacific Northwest to study questions ranging from megathrust earthquakes to volcanic arc structure to the formation, deformation and hydration of the Juan De Fuca and Gorda plates.
As part of the 2009 Stimulus or ARRA (American Recovery and Reinvestment Act) spending, NSF’s Ocean Sciences (OCE) division funded the construction of an amphibious array of 60 Ocean Bottom Seismometers by the three IIC’s for OBSIP.
Twenty of the Lamont OBSs will be installed in trawl-resis- tant enclosures and will be available for deployments in water depths extending from the shelf down to 1,000 m. These 20 OBSs will be deployed via the ship’s wire and recovered using a Remotely-Operated Vehicle.
The OBSs will be utilized in four one-year deployments. These experiments will provide an offshore extension of the Earth- Scope Transportable Array (~70 km spacing) as well as 3 dense experiments focused on either imaging various properties of the thrust interface and forearc or recording local seismicity.
Cascadia Cruises are led by the Cascadia Initiative Epedition Team (CIET), comprised of the following team of scientists:
During 2014, OBSIP will support the following Cascadia cruises:
During 2013, OBSIP supported the following Cascadia cruises:
During 2012, OBSIP supported the following Cascadia cruises:
The OBSIP Management Office (OMO) has restricted access to the Cascadia Initiative dataset (network ID 7D) at the IRIS Data Management Center (DMC) in order to resolve a channel naming error that results in a large number of stations having an incorrect relative orientation.
The channel-naming errors affected LDEO OBS data in Year 1 and Year 2 and the SIO OBS data for Year 2. As a result of this change, OBSIP will make all of the Cascadia Initiative data consistent in relative orientation.
The relative orientation of the horizontal components for the Cascadia Stations were incorrectly defined. There are two options for the relative orientation of the horizontal channels.
Because OBSIP instruments are built and operated by three different IIC's, the usage of default relative horizontal orientation of channels varied in Year 1. In Year 2, all of the data was intended to be uploaded in the GSN convention (BH2 90° CW of BH1). The Cascadia data is now being corrected from both Year 1 and Year 2 so that all data follows the GSN convention (BH2 90° CW of BH1).
UPDATED CONVENTIONS (after restriction)
PREVIOUS CONVENTIONS (prior to restriction)
If you have any questions, please contact Jessica Lodewyk at jessica.lodewyk (at) iris.edu
The OBSIP Management Office has generated horizontal orientations for the first year of Cascadia OBS deployments.
The current version is: 2.0
This report can still be used with the caveat that the LDEO stations have the correct reported values for mean true orientations, but the channel convention was not defined correctly. The mean true orientations would be for HH2 (assuming North = 0 and positive measured clockwise). The HH1 component orientation is 90 degrees counterclockwise from BH2. This is different from what is published in the report where the mean true orientations would be for HH1 and the HH2 component is 90 degrees clockwise from HH1.
The report and its appendicies can be downloaded with the following links: