Magnitude 4.6 Earthquake of Annaka, Japan 2015-04-12

2015-04-12 06:25:15 (UTC) :NorthWest of Annaka, Japan

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Magnitude : 4.6

Event Time: Time and Date Starting of Earthquake Rupture 

• 2015-04-12 06:25:15 (UTC)

Earthquake data:

Location : Position of Epicenter 

36.411°N 138.819°E

Depth : Depth of starting Rupture 

147.3 km

Region : Annaka, Japan

Directions and Distances :Directions and Distances from Geographical Reference in Close Proximity Which can be effected by Location Uncertainty

a) 12km (7mi) NW of Annaka, Japan

b) 16km (10mi) W of Kaneko, Japan

c) 18km (11mi) WSW of Shibukawa, Japan

d) 19km (12mi) NNW of Tomioka, Japan

e) 112km (70mi) NW of Tokyo, Japan

Location Uncertainty: 

Parameter	Value	Uncertainty
Magnitude	4.6 mb	± 0.1
Location	36.411°N 138.819°E	± 5.6 km
Depth	147.3 km	± 5.1
Number of Phase Applied1	126
Minimum Distance2	57.11 km (0.51°)
Travel Time Residual3	0.79 sec
Azimuthal Gap4	53°

¹Number of phase Applied: 

In determining location of hypocenter, applied number of observations on P waves and S waves. The greater the more accurate prediction of EQ.

²Minimum Distance:

 Horizontal distance of nearest Station measured in Km from epicenter. The smaller the more accuracy in prediction of depth of EQ.

³Travel Time Residual:

 A way of measurement of fit of arrival time observed to arrival time predicted for particular location. The smaller the better fit of data.

⁴Azimuthal Gap: 

Expressed in degree; the smaller the smaller the error in horizontal positioning of EQ. Large uncertainty is considered when exceeds 180° (both depth and location)