数据说明

ndk文件每5行存储一个地震事件，有用信息记录如下

第一行

1. reference catalog: PDE for USGS, ISC for ISC catalog
2. date
3. time
4. latitude
5. longitude
6. depth
7. mag 两种震级格式的大小 Mb Ms

第二行，

1. event name: 14-characters
2. data used in the inversion: B,Long-period body waves S,intermediate-period surface waves M,long-period mantle waves
3. type of source CMT: 0 ,general moment tensor CMT: 1 ,moment tensor with constrain of zero trace(standard) CMT: 2 ,double-couple source
4. type and duration of moment-rate function notice that the value given is half the duration

第三行

1. centroid parameters in the inversion
2. type of depth FREE: a result of the inversion FIX: indicates that the depth is fixed and not inverted for BDY: based on model of broad-band P waveforms
3. timestamp it is useful to distinguish Quick CMTs and standard CMTs Q- :Quick CMTs S- :standard CMTs

第四行

1. exponent 指定矩张量指数级的大小 例如，exponent=24,表明后面所有矩张量的值都要乘 10**24
2. six moment-tensor elements Mrr,Mtt,Mpp,Mrt,Mrp,Mtp r: up t: south p: east notice that each moment-tensor element is followed by its standard error

第五行

1. version code useless
2. moment-tensor expressed in its principal-axis system:eigenvalue,plunge and azimuth of the three eigenvectors. eigenvalue, should be multiplied by 10**(exponent) plunge azimuth the order is: t-eigen,t-plu,t-azi,b-eigen,b-plu,b-azi,p-eigen,p-plu,p-azi
3. scalar moment , to be multiplied by 10**(exponent)
4. strike,dip,rake