Strong earthquakes off Mexico in September 2017

[StevieTNZ]

I see this as breaking news: https://www.stuff.co.nz/world/americas/96665395/strong-earthquake-hits-off-coast-of-mexico

An earthquake of magnitude 8 struck off the southern coast of Mexico, the US Geological Survey (USGS) said, shaking buildings in the capital city.

Everything is fluid at the moment, so updates and revisions will be forthcoming. A tsunami threat for NZ is being assessed.

 

[davenn]

I see this as breaking news: https://www.stuff.co.nz/world/americas/96665395/strong-earthquake-hits-off-coast-of-mexico
Everything is fluid at the moment, so updates and revisions will be forthcoming. A tsunami threat for NZ is being assessed.

ya just beat me to it

was about to post

M 8.0 - 96km SW of Pijijiapan, Mexico

Time: 2017-09-08 04:49:17 (UTC)
Location: 15.029°N 93.807°W
Depth: 35.0 km

tis still coming in on my seismo ...

http://www.sydneystormcity.com/seismograms.htm

 

[StevieTNZ]

Upgraded to 8.2 now. Also, there was something about a 6.1mag earthquake in the northern pacific island?

 

[davenn]

Upgraded to 8.2 now. Also, there was something about a 6.1mag earthquake in the northern pacific island?

where did you get the 8.2 from ?

USGS are saying 8.1

M 8.1 - 87km SW of Pijijiapan, MexicoI'm surprised that it is even a M8 considering how small the amplitude on my seismograph is
Dave

 

[StevieTNZ]

where did you get the 8.2 from ?

USGS are saying 8.1

M 8.1 - 87km SW of Pijijiapan, MexicoI'm surprised that it is even a M8 considering how small the amplitude on my seismograph is
Dave

From stuff.co.nz, but saw that USGS were giving it a mag. 8.1.

Here is a live blog feed: https://www.stuff.co.nz/world/americas/96666340/live-mexico-hit-by-powerful-earthquake

 

[davenn]

From stuff.co.nz, but saw that USGS were giving it a mag. 8.1.

Here is a live blog feed: https://www.stuff.co.nz/world/americas/96666340/live-mexico-hit-by-powerful-earthquake

ahhh OK ... always pays to go to the source
all media outlets are notoriously bad with their reporting

 

[Borg]

ahhh OK ... always pays to go to the source
all media outlets are notoriously bad with their reporting

Yahoo is determined to be the most inaccurate. One of their RSS feeds was saying that it was 8.4.

 

[davenn]

4 hours later and there is still low level signal coming in on my seismo

 

[StevieTNZ]

https://www.stuff.co.nz/world/americas/96665395/strong-earthquake-hits-off-coast-of-mexico

At least 58 dead already.

https://www.stuff.co.nz/national/96...ng-for-new-zealand-after-8m-mexico-earthquake

In the video on the 2nd link, does anyone know what causes the sky to light up as it did after the quake? Is that activity correlated with quakes?

 

[fresh_42]

To me it looks like an ordinary lightning storm in summer. More interesting is the tsunami warning. Could it really travel thus far?

 

[StevieTNZ]

More interesting is the tsunami warning. Could it really travel thus far?

In fact I've just seen this: "Tidal gauges are providing evidence of the first waves arriving at Chatham Islands and East Cape, consistent with GNS Science predictions."
But they are small waves, and no evacuation orders have been given.

 

[fresh_42]

In fact I've just seen this: "Tidal gauges are providing evidence of the first waves arriving at Chatham Islands and East Cape, consistent with GNS Science predictions."
But they are small waves, and no evacuation orders have been given.

Although there are no major barriers on the surface between Mexico and NZ, I would think that the Marianne trench would play a major role for deep sea waves, i.e. I'd expected them to dive there and get scattered. But I've never had a course on fluid dynamics, so this might be wrong. Could be an interesting thread.

 

[davenn]

In the video on the 2nd link, does anyone know what causes the sky to light up as it did after the quake? Is that activity correlated with quakes?

To me it looks like an ordinary lightning storm in summer.

if you look closely, you will see the flashes are originating on the ground and then lighting up the clouds above

Simple and easy explanation ... arcing of electrical systems and explosions of transformers etc in substations
as the power lines are swinging all over place and contacting each other

More interesting is the tsunami warning. Could it really travel thus far?

tsunamis regularly cross the Pacific Ocean with ease

Although there are no major barriers on the surface between Mexico and NZ, I would think that the Marianne trench would play a major role for deep sea waves,

I assume you mean the Mariana Trench

It won't affect how the tsunami arrives in NZDave

 

[davenn]

raw and processed seismograms from my recorder

Dave

 

[davenn]

A classic example of a unilateral rupture ( rupture on the fault starts in one place and goes in one direction only)

also been noting in the media that they are all saying that this is the largest Mexican quake in 100 years
They all seem to be forgetting about the M8.0/8.1 in 1985 that devastated Mexico City that killed more than 5000 people
and did horrific damage

many references on the www
https://www.bing.com/search?q=1985+...&src=IE-SearchBox&FORM=IENTTR&conversationid=Dave

 

[Sue Rich]

Great information, everyone.

 

[1oldman2]

Simple and easy explanation ... arcing of electrical systems and explosions of transformers etc in substations
as the power lines are swinging all over place and contacting each other

Dang... these guys made it sound so mysterious, but you're right, that does look like an electrical substation blowing its top.
https://www.newscientist.com/articl...n-the-sky-seen-after-mexicos-huge-earthquake/

 

[StevieTNZ]

Now we have the horrific quake that struck Mexico City. https://www.stuff.co.nz/world/americas/97025447/major-earthquake-shakes-mexico-city

I'll let Dave post any graphs his instruments have picked up, to start a new thread.

 

[davenn]

I'll let Dave post any graphs his instruments have picked up, to start a new thread.

we will keep it in here since the thread title accounts for it

M 7.1 - 5km ENE of Raboso, Mexico

Time: 2017-09-19 18:14:39 (UTC)
Location: 18.584°N 98.399°W
Depth: 51.0 km

a raw seismogram of the M7.1 from my recorder... I haven't had a chance to process it yet
note the much smaller amplitude compared to the M8.1 up the thread post#14

only 120km SSE of downtown Mexico City

Dave

 

[davenn]

interesting article relating to the M7.1 and the lack of significant aftershocks

http://earthquakes.berkeley.edu/blog/2017/09/20/a-shock-without-aftershocks.htmlDave

 

[davenn]

Updated aftershock zone for the M8.1

Events M4.5 and greater for the 8th Sept to 24th Sept

still clearly showing a unilateral rupture in the nor-westerly direction

cheers
Dave