M7.3, 117km east of East Cape - 05/03/21

[Awhituobs]

we were staying by the water in hawkes bay
we headed for the hills!

[Cyclone Tracy]

Loud and clear here. I registered a M7.3, 10km depth on my private network which is much shallower than Geonet's 90 km . USGS was also much shallower as well at 20km.....

[tgsnoopy]

Something woke me about 2.20am, I wonder if that is what it was.

[David]

Tend to believe the geonet depth assessment, apparently some in Dunedin felt it which supports that theory better then a shallow one.

Not sure if it shook here, but I'm a light sleeper and was not woken by it. The last time I felt one was the local 2013 one under Motutapu island.

[tgsnoopy]

Magnitude 7.1, Fri Mar 5 2021 2:27 AM
105 km east of Te Araroa Depth 90 km.

https://www.geonet.org.nz/earthquake/2021p169083

[Orion]

we were staying by the water in hawkes bay
we headed for the hills!

Very wise!

[Awhituobs]

kermadec island tsunami gauges offline after 8 quake!

[Nev]

Geonet has revised yesterday's early morning major quake from M7.1 to M7.2, and its depth from 90 km to just 12 km, which is more in line with the USGS's M7.3 at 21 km deep. However, Geonet's distance from East Cape also increases from about 93 km to about 117 km, compared to 81 km from USGS.

To date, Geonet have reported 8 nearby aftershocks of M5.0 or more, the highest being an M5.4. Coincidently, one of those, an M5.0, occurred just 2.5 minutes before the M8.1 (USGS) Kermadec great quake.

[Nev]

Another M6.1 aftershock at 1:16pm today (plus an M5.0 at 1.51pm)...

https://www.geonet.org.nz/earthquake/2021p173004

[Cyclone Tracy]

Another 2 quakes around M6 in the last half an hour around the Kermadecs.

I got today's one fairly crisp again. My private network registered it as a M6.3, at around 10km. USGS also had it as a M6.3 at 9km. I saw online a GeoNet seismologist admitting they were having trouble with depth errors on both the Hikurangi zone and Kermadec trench quakes relating to the GeoNet estimates.

[Cyclone Tracy]

I've been scratching my head in the last 24 hours about my private network registering 2 quakes on this event. The first quake registered at 6.9 with the 2nd quake 3 seconds later coming in at 7.3. All public agencies only registered 1 quake.

Overnight, a world leading seismologist has found there was indeed 2 events. This would also explain the depth differences between agencies. GeoNet today are looking at his analysis.

[David]

I've been scratching my head in the last 24 hours about my private network registering 2 quakes on this event

What is this private network you speak of, interested

[Cyclone Tracy]

I've been scratching my head in the last 24 hours about my private network registering 2 quakes on this event

What is this private network you speak of, interested

Raspberry shake - https://shakenet.raspberryshake.org/

[tgsnoopy]

What is this private network you speak of, interested

Raspberry shake - https://shakenet.raspberryshake.org/

More expensive than I anticipated. Under consideration all the same.

https://raspberryshake.org/products/

[Awhituobs]

I have a raspberry pi
which shake model do you have cyclone tracy?

[David]

This looks really cool, kinda keen on the 4D one now

[Cyclone Tracy]

I have a raspberry pi
which shake model do you have cyclone tracy?

You have the option to build your own as they offer parts separately, if you already have the raspberry pi. I bought the 4D a couple of years ago from Raspberry shake. The 4D model also has a 3 dimensional accelerometer for lateral motion in case the big one hits close by. The 1D is all good though.

The RS private network is brilliant and has recent new phone apps that has made it even better. As well as normal citizens, many seismologists have these shake devices at home now and they are increasingly used by science agencies globally.

[ricky]

I've got a kit for one of those here somewhere. I think it has 3 geophones.. Been meaning to put it together one day!

Interesting they use mems sensors in the 4D, I do a lot of work with LSM6DSL devices and they are very sensitive at high gain!

[Cyclone Tracy]

Tend to believe the geonet depth assessment, apparently some in Dunedin felt it which supports that theory better then a shallow one.

FYI - GeoNet have now adjusted the M7.2 main shock from 90km to 12km depth.


https://www.geonet.org.nz/earthquake/hi ... 021p169083

[David]

Tend to believe the geonet depth assessment, apparently some in Dunedin felt it which supports that theory better then a shallow one.

FYI - GeoNet have now adjusted the M7.2 main shock from 90km to 12km depth.


https://www.geonet.org.nz/earthquake/hi ... 021p169083

Yes I saw that, was a bit surprised some felt it so far away in the South Island given its shallower depth

[Awhituobs]

quakes on fault lines tend to get felt along way away on a connected fault lines it seems?

[Cyclone Tracy]

A quake that large certainly has downstream referral affects even at shallow levels, as seen in the Kermadecs not long afterwards. Sort of related to your point, I find it interesting the location of this quake is very near the M7.1 on the Hikurangi subduction zone on 2nd Sept 2016. Kaikaoura M7.8 was 73 days later.

[Nev]

Geonet has revised yesterday's early morning major quake from M7.1 to M7.2, and its depth from 90 km to just 12 km, which is more in line with the USGS's M7.3 at 21 km deep. However, Geonet's distance from East Cape also increases from about 93 km to about 117 km, compared to 81 km from USGS.

GeoNet upgraded Friday's main quake from M7.2 to M7.3 this morning.
The depth and location remain the same.

[Awhituobs]

7.3 explains why it why the shaking lasted a good minute, yes?

[Nev]

7.3 explains why it why the shaking lasted a good minute, yes?

There's a few other variables, but yes, I think an M7.3 releases almost twice as much energy than an M7.1.

Cool video below shows the exponential energy release between magnitudes: