NZStrongMotion

The original NZ strong motion database can be downloaded from this page.

The ground motions are processed and compiled into separate files. Please download the archive first before using any recordings. Users may need 7-Zip to unpack the archive.

type	link
acceleration	download
velocity	download
displacement	download

The archive contains all 756 displacement, velocity and acceleration histories along three directions. That totals 6804 records.

The script used to process the original data is available here.

Syntax

amplitude NZStrongMotion (1) (2)
# (1) int, unique amplitude tag
# (2) string, record name

It must be noted that the amplitudes are normalized so that the maximum absolute magnitude is unity. Hence, to achieve a target PGA/PGV/PGD, it shall be assigned to the magnitude of the applied load.

Usage

For example, to load the accelerogram 20110221_235142_CSHS_N76W_A, which is one of the 2011 Christchurch earthquake recordings, user shall first extract the file 20110221_235142_CSHS_N76W_A from NZStrongMotion.7z and place it where the program can locate, for example, the current working folder.

To define such an amplitude, one can use

amplitude NZStrongMotion 1 20110221_235142_CSHS_N76W_A

Explanation of File Format

The format of original file can be seen here.

The processed archive first extract accelerogram name from the file, then read how many acceleration values shall be read and the interval between two records, then read all values and scale them by multiplying each by $1000$ and store them into an integer array. The array has the following layout.

index	value ($\times1000$)
0	time interval of the record in seconds
1	absolute maximum record value
2	value at first time point
3	value at second time point
4	value at third time point
5	...