There were two severe earthquakes off the coast of Gisborne in March and May 1947, each generating large tsunamis in the surrounding area.
| PublicID | 1543047 |
| UTC Time | 1947-05-17T07:06:23Z |
| Latitude | -38.42 (± 0.0 km) |
| Longitude | 178.87 (± 0.0 km) |
| Depth | 12 km (± 0 km) |
| Depth Type | operator assigned |
| Earth Model | nz1dr |
| Used Phase Count | 5 |
| Used Station Count | 4 |
| Standard Error | 0.17 (s) |
| Azimuthal Gap | 309.00 (degrees) |
| Minimum Distance | 1.40 (degrees) |
| Type | Magnitude | Station Count |
| Preferred (Mw) | 6.9 | |
| ML | 5.6 (± 0.1) | 4 |
| Mw | 6.9 | 0 |
| MS | 7.2 | 0 |
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.