OHLN - Ohlone Park, Hercules, CA, USA
We operate broadband and borehole stations under the network code BK. The Berkeley Digital Seismic Network (BDSN) is a regional network of very broadband and strong motion seismic stations designed to monitor regional seismic activity as well as provide high quality data. The Berkeley borehole stations have borehole geophones or other seismic sensors and may have other geophysical instrumentation.
BARD is our GPS network for monitoring crustal deformation across the Pacific-North America plate boundary and in the San Francisco Bay Area for earthquake hazard reduction studies and rapid earthquake emergency response assessment
|Station Name||OHLN (OHLN)|
|In Operation||2001/10/05 00:00:00 - Present|
LocationOHLN is one of five sites installed as a pilot test for the Plate Boundary Observatory, known informally as the Mini-PBO project. This site is known as SFOHL in the USGS Low Frequency Network and is located in Ohlone Park, in Hercules, CA.
NetworkMini Plate Boundary Observatory Network (BK)
Bay Area Regional Deformation Network Network (BARD)
USGS Low Frequency Network (UL)
Sandstone, shale, siltstone, conglomerate, and breccia
Borehole ConditionsThe OHLN borehole was the first of the MiniPBO sites to be drilled and was installed on 7/16/2001. The strainmeter is emplaced at a depth of 670.5 ft and the seismometer is at a depth of 645.5 ft. This figure shows the location of equipment in the borehole.
GPS Monument Description1.25" pipe bolted into borehole casing
Seismic Station Pictures
Installation of strainmeter at OHLN
Completed OHLN site, with GPS monument
GPS Station Timeseries
- Time series processing at the BSL *
Last year Clean Clean & detrended Raw Raw & detrended Lifetime Clean Clean & detrended Raw Raw & detrended Text file (final results only) Clean Raw
GPS Station Pictures
Table of Seismic Instrumentation
|Geophone||Mark Products L-22 Horizontal Geophone||Q330-GFE||EP?,LP?,SP?||40|
|Mark Products L-22 Vertical Geophone||Q330-GFE||EP?,LP?,SP?||40|
|Paroscientific 8WD Digital Pressure Meter||Q330-GFE||LD?||40|
|Sacks 3-component Tensor Strainmeter||Q330-GFE||BS?,HS?,LS?||40|
|Setra Systems Model 270 Barometer||QEP||LD?||EP|
|GPS||Septentrio PolaRx5||Ashtech Choke-Ring||SCIGN Tall||-|
Waveforms and associated metadata, and GPS data, are available at the Northern California Earthquake Data Center (NCEDC).
- BK Information Directory, including
- List of station locations
- List of available channels
- Instrument Response
- Querying the archives
- Download waveform data
- Site log: ohln.log
Data Type From To Low-rate raw 11/21/2001 10/6/2003 Low-rate rinex 11/21/2001 present High-rate raw 10/6/2003 present High-rate rinex 5/1/2010 present
GPS Data Quality
Data completeness is defined both as "Completeness of observations" and "Cycle slips per observation". "Completeness of Obs." is the number of epochs in the final RINEX file normalized to the expected number. This percentage will go down if time is missing from the RINEX file. "Cycle slips per Obs." is the total number of detected cycle slip normalized to the total number of observations in the RINEX file. This number will increase as the receiver loses lock on satellites more frequently.
The effects of multipath on the data are estimated by parameters for L1 and L2 (MP1 and MP2 respectively); see Estey and Meertens (GPS Solutions, 1999) for derivation. The daily value is the RMS of MP1 and MP2 throughout the day and for all satellites. Higher values indicate a greater prevalence and/or strength of multipathing, i.e. objects on the ground are providing multiple reflection pathways from the satellite to antenna.
The Signal-to-Noise ratios are the mean values above the QC elevation mask for L1 and L2 respectively.