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General Comments

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Data Set

Directory Name in the CD : USGS_MENLO_USA

DATA PARTICULARS

1. The number of records provided in this group are considerably less than the number of recorded events. False and faulty triggers have been sieved out. The tables reflect those records with signals that the researcher will have to further look into before using them.

2. The original data files are in binary format.

3. The file names follow GEOS format and indicate the date of the event, UTC time and the component. {e.g. 257K17C1.FOC stands for Julian Day 257, ....., Station FOC] . Each record is identified by computer filename, a unique 13-character string constructed from the start-of-record time (UTC), component, and station name: characters 1-3 = day of year (001-366), characters 4-5 = hour (00-23), characters 6-7 = minute (00-59), character 8 = second code (A-T, where A = 0.000-2.999, B = 3.000-5.999, ..., T = 57.000-59.999), character 9 = component code (1 for vertical-component acceleration, 2 and 3 for horizontal-component acceleration, 4 for vertical-component velocity, 5 and 6 for horizontal-component velocity), character 10 = '.', and characters 11-13 = station name. [See also http://nsmp.wr.usgs.gov/geos/LPE/OFR_90-503/Loma_Prieta.html#Sensor Orientations].

4. The records contained in the data base are arranged so that each record-file represents one event for one component of motion at one station. These are tabulated in the excel files specific to USGS-Menlo.

5. Each new ASCII record-file, identified by its name, has a short header that indicates (a) the component orientation, (b) total length of record (number of data points), (c) sampling interval, and (d) the unit of motion (cm/s or cm/s/s). For example, sampling interval for all USGS-Menlo data is 0.005 s.

6. No corrections of data signals have been made. Spectral values are not computed or provided.

7. For each source of data, a specific file describes the station identity, coordinates, and event time if available.

8. Detailed geotechnical description of the stations are not available. However, all deployments related to USGS-Menlo data set are on alluvial ground. The depth and particular log information on any site is not known.