OHLN - Ohlone Park

Location

OHLN 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.

Network

Mini Plate Boundary Observatory Network (BK)
Bay Area Regional Deformation Network Network (BARD)
USGS Low Frequency Network (UL)

Geology

Sandstone, shale, siltstone, conglomerate, and breccia

Borehole Conditions

The 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 Description

1.25" pipe bolted into borehole casing

Seismic Station Pictures

Installation of strainmeter at OHLN Courtesy of the USGS

Completed OHLN site, with GPS monument

GPS Station Daily Timeseries

• USGS Timeseries (GIPSY)
• UNR Timeseries (GIPSY)

GPS Station Pictures

OHLN GPS monument

OHLN

Table of Seismic Instrumentation

	Sensor	Datalogger	SEED Channels	Location
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
	Sensor	Datalogger	SEED Channels	Location
Auxiliary	AntennaCurrent	Q330-GFE	VE?	40
	ClockPhase	Q330-GFE	LC?,VC?	40
	ClockQuality	Q330-GFE	LC?,VC?	40
	InputVoltage	Q330-GFE	VE?	40
	Paroscientific 8WD Digital Pressure Meter	Q330-GFE	LD?	40
	Sacks 3-component Tensor Strainmeter	Q330-GFE	BS?,HS?,LS?	40
	SystemCurrent	Q330-GFE	VE?	40
	SystemTemperature	Q330-GFE	VK?	40
	VCOValue	Q330-GFE	VC?	40
	CalibrationInput	QEP	LC?	EP
	Humidity	QEP	LI?	EP
	Pinnacle5000	QEP	BA?,LA?	EP
	Pressure	QEP	LD?	EP
	Setra Systems Model 270 Barometer	QEP	LD?	EP
	Temperature	QEP	LK?	EP

GPS Instrumentation

	Receiver	Antenna	Radome	-
GPS	SEPTENTRIO POLARX5	SEPTENTRIO SEPCHOKE_B3E6	SPKE	-

Waveforms and associated metadata, and GPS data, are available at the Northern California Earthquake Data Center (NCEDC).

Waveform Data

• BK Information Directory, including
  • List of station locations
  • List of available channels
    • Year/month/day format
    • Year,doy format
  • Instrument Response
    • SEED format
    • Simplified Responses

• Querying the archives
  • SeismiQuery at the NCEDC
• Download waveform data

GPS 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

Noise Analysis

View more noise plots

GPS Data Quality

Completeness

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.

Previous Year

Lifetime

Multipath

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.

Previous Year

Lifetime

Signal-to-Noise Ratio

The Signal-to-Noise ratios are the mean values above the QC elevation mask for L1 and L2 respectively.

Previous Year

Lifetime