Magnitude 4.3, Wed Nov 24 2021 6:47 AM


Download Event Information


Origin


PublicID 2021p883091
UTC Time 2021-11-23T17:47:50Z
Latitude -20.68 (± 12.3 km)
Longitude -177.51 (± 64.4 km)
Depth 388 km (± 23 km)
Depth Type free
Earth Model iasp91
Used Phase Count 10
Used Station Count 8
Standard Error 0.65 (s)
Azimuthal Gap 335.88 (degrees)
Minimum Distance 8.56 (degrees)

Magnitudes


Type Magnitude Station Count
Preferred (mB) 4.3 (± 0.1)  
mB 4.3 (± 0.1) 7

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


-6.0-4.0-2.00.02.04.06.0residual (s)02468101214161820Distance (degrees)Pick Residuals

Station Magnitudes (mB)


0.01.02.03.04.05.0Magnitude1820Distance (degrees)Station Magnitudes (mB)

Magnitude Residuals (mB)


-1.00.01.0Residual1820Distance (degrees)Magnitude Residuals (mB)