This earthquake followed two earlier shakes of magnitude 5.7 and 5.8 in the previous two days. It caused damage to buildings on both sides of Cook Strait.
| PublicID | 2013p543824 |
| UTC Time | 2013-07-21T05:09:30Z |
| Latitude | -41.60 (± 0.8 km) |
| Longitude | 174.32 (± 0.8 km) |
| Depth | 16 km (± 2 km) |
| Depth Type | free |
| Earth Model | nz3drx |
| Used Phase Count | 52 |
| Used Station Count | 45 |
| Standard Error | 0.36 (s) |
| Azimuthal Gap | 120.97 (degrees) |
| Minimum Distance | 0.17 (degrees) |
| Type | Magnitude | Station Count |
| Preferred (M) | 6.5 | |
| MLv | 6.5 (± 0.3) | 24 |
| ML | 6.8 (± 0.2) | 18 |
| M | 6.5 | 24 |
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).
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.