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MHC - Lick Observatory, Mt. Hamiliton, CA, USA
- Location:
-
Site is located at the
Lick Observatory atop
Mount Hamilton, and is under the auspices of UC
Santa Cruz. The site was first established in 1887 with the installation
of the first seismic sensors in North America, and has been occupied continuously
since then. Wood-Anderson seismographs were deployed at this site in 1928
and operated until 1993. The first digital broadband instrumentation
was deployed in 1987.
- Geology:
-
Jurassic-Cretaceous Franciscan greywacke and greenstone
- Vault/Borehole conditions:
-
The vault is located in a room in the east wing of the Lick Observatory.
The piers are reinforced concrete which are isolated from the building.
The seismometer room is isolated from the hallway via two
doors and the datalogger and supporting equipment are in
an adjacent room. The seismometers are thermally insulated
with 4" of polyurethane foam.
- Instrumentation:
-
| Sensor | Datalogger | Start Date | End Date | SEED Channels | Location |
| Battery Voltage | Q935 | 2001/06/01 | Present | UE?,LE? | |
| Internal Temperature | Q935 | 2001/06/01 | Present | UK? | |
| Kinemetrics FBA ES-T Accel. (2 g max 10 v/g) | Q935 | 2005/04/08 | Present | LL?,BL?,HL? | |
| Kinemetrics FBA-23 Accel. (2 g max 1.25 v/g) | Q935 | 1992/04/29 | 2005/04/08 | LL?,HL?,BL? | |
| Motorola MPX201 Pressure | Q935 | 1996/04/09 | Present | LD? | |
| Streckeisen STS-1 VBB Feedback Seismometer | Q935 | 1986/09/10 | Present | LH?,SH?,BH? | |
| Streckeisen STS-1 VBB Feedback Seismometer | Q935 | 1992/04/29 | Present | VH?,HH?,UH? | |
| Streckeisen STS-1 VBB Feedback Seismometer | Q935 | 2001/06/01 | Present | UM? | |
| YSI 44031 Thermistor | Q935 | 1996/04/09 | Present | LK? | |
The MHC site also is home to a continuously operating
GPS receiver (MHCB) as part of the BARD
network.
- Network:
-
BK (Berkeley Digital Seismic Network)
- Operation Notes: (may not be current)
- This section summarizes major changes in equipment or in instrumentation at MHC.
- 06/15/2004: Changed BH channels sampling rate to 40 Hz.
- 12/16/1999: Q980 software upgraded to MSHEAR.
- 04/22/1999: Replaced GOES with GPS clock. Upgraded Q980 with 4 GB disk. Installed ethernet card.
- 12/16/1997: Q980 software upgraded to newest version of USHEAR.
- 06/14/1996: Installed GPS receiver on roof of neighboring building.
- 02/23/1996: Barometer and thermometer package installed.
- 11/21/1995: Telemetry moved to frame-relay.
- 06/12/1995: Software upgraded to USHEAR.
- 02/02/1993: Replaced Streckeisen STS-1/UVBB seismometers replaced with a set of STS-1/VBB. The VBB instruments have a 10 Hz high-frequency corner while the UVBB have a 5 Hz corner.
- 10/22/1992: The polarity of the NS channel of the STS-1 seismometer was corrected. From 04/29/92-10/22/92, the polarity of this channel was reversed and the sign of the Sd coefficient reflects this reversal.
- 05/05/1992: Changed line-driver gain on the STS-1.
- 04/29/1992: Replaced the 16-bit PC-based datalogger with the 24-bit Quanterra Q980 system.
- 10/27/1987: The Streckeisen STS-1/UVBB seismometers were installed with a PC-based datalogging system.
- Noise Characteristics:
-
The figures below are cumulative plots of power spectral density (psd)
determined from the broadband channels. In each figure, the vertical
component psd is plotted with blue diamonds, the north component
psd with red squares, and the east component psd with green circles.
The results are presented in the 5 different frequency bands, and
the USGS/Albuquerque low noise model is plotted as a dashed line in each.
The PSD units are in dB (decibel) relative to 1 (m/s**2)**2/Hz. The current
annual plot is updated weekly.
| Cumulative PSD results |
| 1999 |
2000 |
2001 |
2002 |
2003 |
2004 |
2005 |
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- Data Availability:
- BDSN waveforms and associated metadata are available at the
Northern California Earthquake Data Center (NCEDC).
Several tools provide access to SEED format data at the
NCEDC, both in terms of querying the archives and
allowing data requests.
- Querying the archives
- Requesting data
Help on using these
tools is available.
Copyright 1995-2005, The Regents of the University of California.
Last modified: Wed Jun 25 13:34:08 PDT 2008
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