# Shallow Shocks (M >= 6.0) in OFF Tohoku Area for 1885-1980

### Description

Earthquakes data used by Yosihiko Ogata in his 1988 JASA paper.

### Usage

1 |

### Format

A `data.frame`

with the following variables:

year: | year of occurrence. |

month: | month of occurrence. |

day: | day of occurrence. |

hour: | hour of occurrence. |

minute: | minute of occurrence. |

magnitude: | magnitude on Richter's scale. |

type: | type of earthquake: `main` (shock), `foreshock` ,
`aftershock` ; according to Utsu. |

Date: | date in days starting from January 1st 1885. |

energy.sqrt: | square root of the energy expressed in erg. |

### Details

Quakes 213 and 214 were given exactly the same dates in Ogata (1988). Quake 214 has here been delayed by 1 minute.

### Source

Ogata (1988) Table 1, pp 14-15.

### References

Ogata, Yosihiko (1988) Statistical Models for Earthquake Occurrences and Residual
Analysis for Point Processes. *Journal of the American
Statistical Association* **83**: 9-27.

### Examples

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 | ```
data(ShallowShocks)
## Reproduce Fig. 2 of Ogata 1988
layout(matrix(1:3, nrow = 3))
plot(ShallowShocks$Date,
cumsum(ShallowShocks$energy.sqrt) / 10^13,
type ="l",
xlab = "",
ylab = "",
main = "Cumulative square root of energy")
plot(ShallowShocks$Date,
cumsum(1+numeric(dim(ShallowShocks)[1])),
type ="l",
xlab = "",
ylab = "",
main = "Cumulative number of shocks")
plot(ShallowShocks$Date,
ShallowShocks$magnitude,
type = "h",
ylim = c(5,9),
xlab = "Time (days)",
ylab = "",
main = "Magnitude vs Occurrence time")
``` |

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