# Guadalajara Earthquake



## TundraGreen (Jul 15, 2010)

We had a modest earthquake in Guadalajara a few minutes ago. It was only a Magnitude 4.5 but it was pretty close, so I could really feel it.

M4.5 - Jalisco, Mexico

2016-05-11 22:35:20 (UTC)
2016-05-11 17:35:20 (UTC-05:00) in your timezone

Nearby Places
6.0 km (3.7 mi) NNE of San Esteban (San Miguel Tateposco), Mexico
13.0 km (8.1 mi) ENE of Tesistán, Mexico
13.7 km (8.5 mi) NE of Nuevo México, Mexico
14.4 km (8.9 mi) NNE of Zapopan, Mexico
20.7 km (12.9 mi) N of Guadalajara, Mexico

20.851°N 103.358°W depth=10.0 km (6.2 mi)


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## AlanMexicali (Jun 1, 2011)

Being 6.2 miles deep is why you felt it strongly. Ones much deeper at 4.5 might not be felt as strongly that close by.


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## TundraGreen (Jul 15, 2010)

AlanMexicali said:


> Being 6.2 miles deep is why you felt it strongly. Ones much deeper at 4.5 might not be felt as strongly that close by.


The UNAM seismic network lists it at 15 km depth and puts it a little to the Northwest. The US site gave it a depth of 10 km = 6.2 mi. I suspect that both are constraining the depth. There probably aren't enough near stations to get a good depth. But either way, you are correct that it is shallow.


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## Isla Verde (Oct 19, 2011)

Glad that you're OK, Will. Did any dishes fall off the shelves?


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## sunnyvmx (Mar 14, 2010)

I was sitting in my recliner in Ajijic. The chair started shifting from side to side and I thought it was very strange. The pup was sitting up in her bed looking bewildered and ChuChu the wondrous parrot was squawking when he should have been asleep so I knew we all felt an earthquake.


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## chuck846 (Jan 15, 2016)

At 6:20AM today I am watching the news and the story is 'hace unos momentos' volcan popocatepetl had an explosion. That stuff just has to all be related...


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## TundraGreen (Jul 15, 2010)

chuck846 said:


> At 6:20AM today I am watching the news and the story is 'hace unos momentos' volcan popocatepetl had an explosion. That stuff just has to all be related...


Just a coincidence. They are too far apart. Popo has been erupting frequently. Volcanic eruptions and earthquakes can be related. It was an earthquake that started the 1980 eruption of Mount St Helens. But in this case, the distance and size of the Gdl earthquake makes any direct connection very unlikely.

They are related in the sense that both are a consequence of the Cocos plate subducting under Mexico. Wikipedia has a good, short article on the Cocos plate and its effects.


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## Isla Verde (Oct 19, 2011)

TundraGreen said:


> Just a coincidence. They are too far apart. Popo has been erupting frequently. Volcanic eruptions and earthquakes can be related. It was an earthquake that started the 1980 eruption of Mount St Helens. But in this case, the distance and size of the Gdl earthquake makes any direct connection very unlikely.
> 
> They are related in the sense that both are a consequence of the Cocos plate subducting under Mexico. Wikipedia has a good, short article on the Cocos plate and its effects.


Thanks for sharing your professional point-of-view, Will!


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## TundraGreen (Jul 15, 2010)

Isla Verde said:


> Thanks for sharing your professional point-of-view, Will!


GIve me too much encouragement and you will get more than you asked for or want.

Case in point: The Mount St Helens eruption was an interesting case. An earthquake caused a landslide which caused a volcanic eruption. Mt St Helens is a volcano in the Cascade range in southwestern Washington State, in the US. In the months before the eruption, magma was forcing its way into the mountain and it caused one side of the mountain to bulge kind of like blowing up a balloon. It was bulging more each day, meters per day. The bulging caused the side of the mountain to be steeper than it could support. On May 18th, 1980, there was a minor earthquake, maybe M 5 or 6, I don't remember exactly. The earthquake caused all that bulging material to slide off the mountain. When the landslide occurred it relieved pressure that had built up within the volcano. It was like uncorking a Champagne bottle. When the landslide occurred the volcano erupted. In addition to throwing stuff up in the air, there was a huge lateral blast out the side where the landslide had occurred. The lateral blast knocked down millions of trees and the hot ash burned all the leaves and bark. It was an impressive scene after the eruption, all black and grey with millions of trees all lying down pointing down hill.


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## Isla Verde (Oct 19, 2011)

TundraGreen said:


> GIve me too much encouragement and you will get more than you asked for or want.
> 
> Case in point: The Mount St Helens eruption was an interesting case. An earthquake caused a landslide which caused a volcanic eruption. Mt St Helens is a volcano in the Cascade range in southwestern Washington State, in the US. In the months before the eruption, magma was forcing its way into the mountain and it caused one side of the mountain to bulge kind of like blowing up a balloon. It was bulging more each day, meters per day. The bulging caused the side of the mountain to be steeper than it could support. On May 18th, 1980, there was a minor earthquake, maybe M 5 or 6, I don't remember exactly. The earthquake caused all that bulging material to slide off the mountain. When the landslide occurred it relieved pressure that had built up within the volcano. It was like uncorking a Champagne bottle. When the landslide occurred the volcano erupted. In addition to throwing stuff up in the air, there was a huge lateral blast out the side where the landslide had occurred. The lateral blast knocked down millions of trees and the hot ash burned all the leaves and bark. It was an impressive scene after the eruption, all black and grey with millions of trees all lying down pointing down hill.


Have you ever had the chance to visit the aftermath of this tectonic super-event?


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## TundraGreen (Jul 15, 2010)

Isla Verde said:


> Have you ever had the chance to visit the aftermath of this tectonic super-event?


I was there about two weeks before it erupted. By coincidence, there was a meeting of the Seismological Society of America just before the eruption. There was a field trip to the side of the volcano. At that time the bulging was very obvious. Then I flew around it in a helicopter doing field work after the eruption. They evacuated most of the people in danger before the eruption. It was obvious something was going to happen. There was one old man, Harry Randall Truman, 84 years old, who refused to leave. He ran a lodge at Spirit Lake. After the eruption the lodge was buried in 150 feet of debris. One volcanologist, David Johnston, was 6 miles from the summit observing the volcano the morning it erupted. He also died from the blast. Neither of their bodies were ever found.


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## tbh (Apr 11, 2015)

TundraGreen said:


> GIve me too much encouragement and you will get more than you asked for or want.
> 
> Case in point: The Mount St Helens eruption was an interesting case. An earthquake caused a landslide which caused a volcanic eruption. Mt St Helens is a volcano in the Cascade range in southwestern Washington State, in the US. ... ... ... When the landslide occurred the volcano erupted. In addition to throwing stuff up in the air, there was a huge lateral blast out the side where the landslide had occurred. The lateral blast knocked down millions of trees and the hot ash burned all the leaves and bark. It was an impressive scene after the eruption, all black and grey with millions of trees all lying down pointing down hill.


I was living downwind in Northern Idaho at the time, ~250+ miles away, and by about midday this inky black sky had completely engulfed us and it was almost dark as night. Then the ash started coming down, about 1/2 to 5/8 inch on everything. People were afraid to go out and breath it, and afraid to drive their cars for fear of destroying their engines. A real mess. (Sorry, a little off topic)


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## Isla Verde (Oct 19, 2011)

TundraGreen said:


> I was there about two weeks before it erupted. By coincidence, there was a meeting of the Seismological Society of America just before the eruption. There was a field trip to the side of the volcano. At that time the bulging was very obvious. Then I flew around it in a helicopter doing field work after the eruption. They evacuated most of the people in danger before the eruption. It was obvious something was going to happen. There was one old man, Harry Randall Truman, 84 years old, who refused to leave. He ran a lodge at Spirit Lake. After the eruption the lodge was buried in 150 feet of debris. One volcanologist, David Johnston, was 6 miles from the summit observing the volcano the morning it erupted. He also died from the blast. Neither of their bodies were ever found.


Wow, what an experience that must have been for you, both before and after the eruption. Do you have any photos you can share with us?


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## sparks (Jun 17, 2007)

Fault lines in the middle of Mexico ??? Usually they are just offshore


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## TundraGreen (Jul 15, 2010)

sparks said:


> Fault lines in the middle of Mexico ??? Usually they are just offshore


The boundary between the Cocos plate and the North American plate is offshore, but there are lots of minor faults on land.


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## Isla Verde (Oct 19, 2011)

TundraGreen said:


> The boundary between the Cocos plate and the North American plate is offshore, but there are lots of minor faults on land.


Living in Mexico, it's great to have an expert in geology as a member of the forum.


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## chuck846 (Jan 15, 2016)

TundraGreen said:


> The boundary between the Cocos plate and the North American plate is offshore, but there are lots of minor faults on land.


We dove someplace - I think Puerto Escondido - where we went in off the beach and perhaps a couple/ few hundred yards offshore there were these big-to large slabs of rock all broken up (the way ice looks when an ice-breaker goes through). I think that was some sort of tectonic plate action. There was very little sea-life - just rocks.


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## chuck846 (Jan 15, 2016)

chuck846 said:


> We dove someplace - I think Puerto Escondido - where we went in off the beach and perhaps a couple/ few hundred yards offshore there were these big-to large slabs of rock all broken up (the way ice looks when an ice-breaker goes through). I think that was some sort of tectonic plate action. There was very little sea-life - just rocks.


Google really is useful 

From a diver's blog on Puerto Escondido : 'Beneath the surface, the American, the Caribbean, and the Cocos tectonic plates collide (in very slow motion, of course!) at a place called Punto de Presión (Pressure Point), a truly unique dive site.'


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