ruaumoko: 1992 Rotoaira/Rotopounamu quakes

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1992 Rotoaira/Rotopounamu quakes

In 1992 there were 25 earthquakes in the Rotoaira/Rotopounamu area.
The first significant earthquake swarm ever recorded in the area started on 29th April and carried on through to the 5th May, with 21 events from 1.129 to 2.971. The spread of the swarm was from north west of Mangatipua Stream in an arc up towards the base of Mt. Tihia and across the Te Ponanga Saddle to Lake Rotopounamu. During the swarm there was one isolated quake at the southern base of Mt. Pihnga, a 2.865 ML which was also the deepest quake in 1992 at a depth of 162km (marked on the map as a magenta coloured orb).
The largest quake in 1992 was not part of the swarm, a 3.062 on the 7th January at 05:15:48.8 UTC, located midway along the Wairehu Canal between Lake Rotoaira and Lake Otamangakau. (marked on the map as a grey coloured orb)

total 25 quakes Rotoaira/Rotopounamu area 1992

total 25 quakes Rotoaira/Rotopounamu area 1992

REF, LAT, LONG, TIME, DEPTH, MAG
299805, -39.0236, 175.66611, 1992/02/07 05:15:48.8, 5, 3.062
324234, -39.01902, 175.72978, 1992/04/26 03:47:30.9, 11, 2.342
327418, -39.02513, 175.6915, 1992/04/29 04:44:28.8, 5, 2.22
328291, -39.03015, 175.67206, 1992/04/29 04:48:46.2, 5, 1.761
328294, -39.03432, 175.6624, 1992/04/29 04:53:47.8, 5, 1.699
328295, -39.03815, 175.677, 1992/04/29 04:59:27.9, 5, 1.129
328300, -39.03363, 175.67418, 1992/04/29 05:48:29.2, 5, 2.971
328312, -39.0216, 175.68364, 1992/04/29 07:07:55.9, 5, 1.532
330940, -39.02167, 175.69261, 1992/04/29 07:14:19.9, 5, 2.404
328315, -39.01883, 175.68108, 1992/04/29 07:18:05.6, 5, 1.538
330943, -39.02275, 175.68829, 1992/04/29 08:31:43.4, 5, 2.374
328341, -39.02221, 175.68088, 1992/04/29 12:03:04.9, 5, 1.781
328352, -39.01917, 175.6862, 1992/04/29 16:02:56.5, 5, 1.78
331280, -39.01621, 175.67789, 1992/04/29 17:02:32.5, 5, 1.239
328386, -39.0214, 175.70891, 1992/04/30 09:18:02.7, 5, 1.582
326565, -39.03775, 175.66115, 1992/04/30 10:27:43.0, 5, 2.128
328388, -39.01502, 175.71938, 1992/04/30 10:44:42.5, 5, 1.559
332030, -39.0568, 175.76836, 1992/05/01 10:07:58.9, 162, 2.865
328419, -39.01594, 175.70006, 1992/05/01 18:46:08.7, 5, 1.811
332034, -39.03352, 175.6924, 1992/05/02 02:26:09.5, 5, 2.601
328037, -39.04249, 175.66858, 1992/05/05 15:43:15.2, 12, 2.426
330356, -39.02277, 175.73714, 1992/05/05 15:46:12.5, 23, 2.262
330357, -39.01891, 175.69135, 1992/05/05 15:47:54.8, 13, 1.729
372103, -39.01703, 175.68542, 1992/09/24 17:40:13.7, 12, 1.345
377829, -39.04677, 175.66429, 1992/10/15 16:23:55.8, 5, 1.682

data by geonet. map by google maps. plots by highace using GPS Visualizer

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Earthquake Swarms

Earthquake swarms are events where a local area experiences sequences of many earthquakes striking in a relatively short period of time. The length of time used to define the swarm itself varies, but the United States Geological Survey points out that an event may be on the order of days, weeks, or months. They are differentiated from earthquakes succeeded by a series of aftershocks by the observation that no single earthquake in the sequence is obviously the main shock. Earthquake swarms are one of the events typically preceding eruptions of volcanoes

Earthquake Aftershocks

An aftershock is an earthquake that occurs after a previous earthquake (the main shock). An aftershock is in the same region of the main shock but is always of smaller magnitude strength. If an aftershock is larger than the main shock, the aftershock is redesignated as the main shock and the original main shock is redesignated as a foreshock. Aftershocks are smaller earthquakes formed as the crust around the displaced fault plane adjusts to the effects of the main shock

Aftershocks are dangerous because they are usually unpredictable, can be of a large magnitude, and can collapse buildings that are damaged from the mainshock. Bigger earthquakes have more and larger aftershocks and the sequences can last for years or even longer especially when a large event occurs in a seismically quiet area; see, for example, the New Madrid Seismic Zone, where events still follow Omori's law from the mainshocks of 1811–1812. An aftershock sequence is deemed to have ended when the rate of seismicity drops back to a background level; i.e., no further decay in the number of events with time can be detected.