Magnitude 4.4 Earthquake of Atka, Alaska USA 2013 August 20

2013-08-20 06:30:34 UTC : Atka, Alaska USA EARTHQUAKE

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Magnitude: 4.4

Event Time: Time and Date Starting of Earthquake Rupture 

1. 2013-08-20 06:30:34 UTC

1. 2013-08-19 18:30:34 UTC-12:00 at epicenter

Earthquake data:

Location : Position of Epicenter 

52.658°N 174.465°W

Depth : Depth of starting Rupture 

205.2km (127.5mi)

Region : Atka, Alaska

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

a) 54km (34mi) NNW of Atka, Alaska

b) 1422km (884mi) SSE of Anadyr', Russia

c) 1757km (1092mi) WSW of Anchorage, Alaska

d) 1784km (1109mi) WSW of Knik-Fairview, Alaska

e) 2530km (1572mi) W of Whitehorse, Canada

Location Uncertainty: 

Parameter	Value	Uncertainty
Magnitude	4.4 mb	± 0.05
Location	52.658°N, 174.466°W	± 20.8 km
Depth	205.2 km	± 6.3 km
Number of Phase Applied1	76
Minimum Distance2	54.5 km (0.49°)
Travel Time Residual3	1.24 sec
Azimuthal Gap4	71°

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)