Magnitude 1.6, Wed Oct 21 2020 2:34 AM


Download Event Information


Origin


PublicID 2020p793420
UTC Time 2020-10-20T13:34:36Z
Latitude -38.89 (± 12.8 km)
Longitude 176.12 (± 20.8 km)
Depth 145 km (± 13 km)
Depth Type free
Earth Model iasp91
Used Phase Count 13
Used Station Count 9
Standard Error 0.56 (s)
Azimuthal Gap 169.24 (degrees)
Minimum Distance 0.24 (degrees)

Magnitudes


Type Magnitude Station Count
Preferred (M) 1.6  
MLv 1.6 (± 0.9) 2
M 1.6 2

GeoNet combines magnitudes into a summary magnitude, M, which consists of a weighted average of the individual magnitudes and attempts to be a best possible compromise between all magnitudes for a range of earthquake sizes. Summary magnitude for GeoNet is then defined as:

M = (2 * MLv + (0.4 * number_of stations(Mw(mB)) - 1) * Mw(mB)) / (2 + (0.4 * number_of_stations(Mw(mB)) - 1))

Where MLv is local magnitude calculated on the vertical component and Mw(mB) is a Mw estimation based of mB by Bormann and Saul (2008).

Origin Map


Map of New Zealand.

Map showing stations with picks used to locate the earthquake. Stations with picks that have a zero weight in the solution are shown as small grey circles. Those with a higher weight are shown as larger circles. The quake is shown by the largest circle.

Pick Residuals


-2.0-1.00.01.02.0residual (s)012Distance (degrees)Pick Residuals

Station Magnitudes (MLv)


0.01.02.03.0Magnitude12Distance (degrees)Station Magnitudes (MLv)

Magnitude Residuals (MLv)


-2.0-1.00.01.02.0Residual12Distance (degrees)Magnitude Residuals (MLv)