Magnitude 3.7 Earthquake of Medford, Oklahoma 2015-04-20

2015-04-20 12:08:31 (UTC) :West of Medford, Oklahoma

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Magnitude : 3.7

Event Time: Time and Date Starting of Earthquake Rupture 

• 2015-04-20 12:08:31 (UTC)

Earthquake data:

Location : Position of Epicenter 

36.822°N 97.861°W

Depth : Depth of starting Rupture 

2.4 km

Region : Medford, Oklahoma

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

a) 11km (7mi) W of Medford, Oklahoma

b) 47km (29mi) N of Enid, Oklahoma

c) 70km (43mi) W of Ponca City, Oklahoma

d) 77km (48mi) WSW of Arkansas City, Kansas

e) 153km (95mi) NNW of Oklahoma City, Oklahoma

Location Uncertainty: 

Parameter	Value	Uncertainty
Magnitude	3.7 mb_lg	± 0.1
Location	36.822°N 97.861°W	± 1.5 km
Depth	2.4 km	± 7.8
Number of Phase Applied1	73
Minimum Distance2	3.23 km (0.03°)
Travel Time Residual3	0.65 sec
Azimuthal Gap4	36°

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)