Selection of La Habra Ground Motion Observations
The La Habra Earthquake was a well recored earthquake. We have selected a set of ground motion data for use in validation of our ground motion simulation results.
Contents
La Habra Data Sets
We have identified five possible sources of observational data for the La Habra Event. Current site list is based on the first two data sets. Additional data from the other data source may be added latter:
We are assuming the two data sets above include a high percentage of the available, high quality observations for this event. If additional observational data is need, places to check include:
StrongMotion.Org (SMO) Observations
As of 28 March, the strong motion.org site has collection of strong motion data in Cosmos format for the La Habra Mw5.1 earthquake. They also have data for an aftershock.
The [strongmotion.org] site gives a list of years, select 2014, and they give you a list of earthquakes. Pick the lower caps, lahabra event, and you get to a selection page, giving list of station, information about the records, and information about whether there are structure recordings.
When a station is selected, the users selects processed, or unprocessed. We select processed. When we get a Zip file, it typically contains two file V2 and V3. The V2 file contains a header indicating the instrument type. For all SCSN, we see HN data (example. SCSN Station WLT: HN data, SCSN Station: , indicating strong motion accelerometer data. The V2 files seem to contain the time series. However, parsing is complicated because the files may contain structure response information time series as well.
After processing the event data table:
- Total of SMO stations: 347
- Total within the simulation region: 309
Based on contents of .V2 files, these StrongMotion.Org data are accelerometer data, channel type HN, so we will assume any CI STAT HN data is a duplicate of what we have from strong motion.org. This is an assumption of what we get from SMO. Once we retrieval all the seismograms, we do not know if this is a good assumption. If not, then some strong motion data are not HN, so we may want to include HN from SCECDC. For now, drop an SCECDC HN as duplicate of SMO data, if network, station match.
SCEC Data Center (SCECDC) Observations
We found another collection of La Habra data in the SCEC Data Center. This is data for EEW and Seismological Algorithm Testing. These station lists are broken out by network, station, instrument, component. We will do two passes to identify that channels this adds to the set.
Based the directory manifest file, this file has a header then list of network, channel, instrument. The channel naming used by SCECDC distinguishes between FBA channels (m/sec2) [HN] and velocity sensor (m/sec) [HH] by the first two characters. For the first pass, we will select only FBA channels for Caltech.
- All Channel List
- Total SCECDC [HN] stations: 267
- Total SCECDC [HN] stations in simulation region: 103
Merged (SMO + SCECDC) Observation Lists
Before reviewing each seismogram, we assume all stations have signal within the simulation region. Then, merging the SMO and SCECDC La Habra Event Data Set, using only acceleration instruments within the simulation region:
- Total SMO and SCECDC [HN] Stations in simulation region : 356
The sites were we have overlapping data, where we can get seismograms from both sources, gives us a way to cross check our ground motion processing is consistent. The overlapping stations are:
- Total Overlapping SMO and SCECDC [HN] Stations in simulation region : 56
Comparing Ground Motion Data
In these merged data sets, we will manage the observational data separately until we have confirmed the processes of each data set. The SMO data will be in the processed V2 cosmos format.
The SCEDC data will be in Counts that will need to be converted to acceleration using a gain factor in the metadata file.
We will consider all the SMO as consistently processed Observational Sites. We need to confirm our processing of the SCEDC event data, and compare our signal processing between data sets for some of the overlapping data sites where we have both SMO data and SCEDC data.
Earlier La Habra Station Lists
Previously contributed station lists from earlier work. We've reviewed this lists to be sure all stations mentioned in these site lists are included in our merged list above:
- En-Jui Station List w/ Simulation Region (KML Format)
- En-Jui Station List (Text Format)
- NK Strong Motion Station List for La Habra (txt)
An earlier site list, that provides station and location information.
Seismological Software Links
- MCEER Data Processing
- IRIS Software
- Orfeus Software
- GeoNet Software
- IRIS Contributed Software
- USGS Data Processing
- Seismsoft (Commercial)
