Earthquake data treatment

All fundamental original data have download from database of Japan Meteorological Agency (JMA). I use only felt earthquakes in Japan as possible data size.

Original data is a set of data as below,

• Date and time of occurrence
• Location Name of epicenter
• latitude longitude of epicenter
  
• Depth of epicenter ([km])
  
• Magnitude (M0.0-M9.9)
• Japanese earthquake scale（10steps） 

I give some arrangements for these basic data as below,

• Date and time of occurrence => Some data are treated as the total value per day
• Location Name of epicenter (Original ones are amorphous, for example, separated land area from sea area) => New rectangle area defined including all original area
• latitude longitude of epicenter => Sometimes used as rounding off to the first decimal place for classification
• Depth of epicenter ([km]) => Sometimes used as rounding off for classification like as 0km/10km/20km/etc. Sometime 1km is used instead of 0km for usage of logarithm scale or product value
  
• Magnitude (M0.0-M9.9) => as is numerical value　
• Japanese earthquake scale（10steps）  => only reference because of secondary parameter

"Details Unknown" with unknown depth as Location Name of epicenter are included in JMA database. The quantity is about 90 thousands against about 220 thousands of all data. "Details Unknown" with no magnitude data is regarded as 0[km] or 1[km].

 

Database of Japan Meteorological Agency (JMA) is sometimes updated.Some data have been added lucking data, and some of them have been deleted.