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geoff_morphini

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Posted: Apr 5, 2024 - 12:32pm

JrzyTmata wrote:

no alerts. just the low rumbles like a big truck was going by.
they're reporting this the biggest quake on record in Philly area. although the one in 2011 (centered in Virginia) shook us a lot more. I saw the frickin' wall and floor waving.

Iâm always a little leery that someoneâs posting a video from another earthquake but the accents give me confidence this is NJ. Note the little dog reacts to the bang and jolt. Thatâs the p-wave. Then the big shaking comes in, thatâs the shear wave (s-wave). There are other waves that follow. The second part of the video, shot down the hall is great as well, can really see the pop of the p-wave. Also, the duration of the earthquake, I count about 5-6 seconds is what we expect from that size event.
https://x.com/rawsalerts/statu...

geoff_morphini

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Posted: Apr 5, 2024 - 12:22pm
How similar sized earthquakes are felt differently on E and W coasts, itâs the rocks https://x.com/seismosue/status...

JrzyTmata

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Posted: Apr 5, 2024 - 10:54am

geoff_morphini wrote:

If you werenât already aware, there is an event page the USGS develops (usually within 5 min of the earthquake). It is here https://earthquake.usgs.gov/ea...

A couple of notable things 1) within that event page is a âDid you feel it?â Inquiry https://earthquake.usgs.gov/ea.... This provides incredible intensity information to develop site attenuation models and such - please consider putting your info in it. 2) there have been over 109, 000 responses thus far! That amazing for a M4.8 event however, 3 things factor in a) lots of people available to experience event, b) shallow (less than 4 km deep (most western eqâs are 10 -15 km or greater and c) your rocks are old, strong and unbroken (like a good bell. The responses are more than 100 miles from the epicenter, Iâll bet people will report it over 200 miles away. That doesnât happen in the west, our bell is not as strong. 3) Most New England earthquakes are caused by glacial rebound (not tectonics). You had kmâs of ice sitting on the crust about 20 - 12 thousand years ago. Thatâs lots of weight. It depressed the crust. The ice suddenly melted (over a few thousand years) and the crust is still âbouncing back.â If you put a significant weight on rocks for a long period of time they will flex (elastically), if you remove that weight quickly they may respond in a brittle way (hence earthquake). 4) one other thing to note - the USGS provides a forecast of potential aftershocks over the next week - in your case you have a 16% chance of having a M4+ and a 46% chance of an M3+ It is very unlikely, but not impossible, that you will feel another the same size or greater.https://earthquake.usgs.gov/ea...

There will be a lot of info to come.

I was at USGA site before they even posted. LOL
I'll post my info there when I get home.

JrzyTmata

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Posted: Apr 5, 2024 - 10:52am

geoff_morphini wrote:

Jrzy, did something alert you to the beginning of the shaking, like a banging sound, a pop or a jolt? The low rumble was likely the shear wave (accompanied by swaying motion). The sudden motion would be the primary (p wave). In smaller earthquakes most people donât realize thatâs what alerted them to the beginning of the event

steeler

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Posted: Apr 5, 2024 - 10:19am

geoff_morphini wrote:

Very interesting. Thanks!

rgio

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Posted: Apr 5, 2024 - 9:36am

geoff_morphini wrote:

Jrzy and I live pretty close to each other...and I heard it...a loud rumble...and then the platter of my turntable started banging into the "walls" of the deck behind me. Given the rain, and the fact that a tree came down in the woods by my house, I was worried that one of the larger trees had fallen on my house.

geoff_morphini

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Posted: Apr 5, 2024 - 9:08am
islander wrote: David Lee Roth running down the street singing "I'm your earthquake man, stop me when I'm passin' by"? HA!

islander

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Posted: Apr 5, 2024 - 9:06am

geoff_morphini wrote:

Jrzy, did something alert you to the beginning of the shaking, like a banging sound, a pop or a jolt? The low rumble was likely the shear wave (accompanied by swaying motion). The sudden motion would be the primary (p wave). In smaller earthquakes most people donât realize thatâs what alerted them to the beginning of the event

David Lee Roth running down the street singing "I'm your earthquake man, stop me when I'm passin' by"?

geoff_morphini

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Posted: Apr 5, 2024 - 9:00am

JrzyTmata wrote:

we just had a 4.7 in northern New Jersey.
we felt a low rumble here in South Jersey.

NeuroJoe

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Posted: Apr 5, 2024 - 8:47am

geoff_morphini wrote:

Super cool, thanks!

geoff_morphini

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Posted: Apr 5, 2024 - 8:37am

JrzyTmata wrote:

we just had a 4.7 in northern New Jersey.
we felt a low rumble here in South Jersey.

Bill_J

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Posted: Apr 5, 2024 - 7:44am
JrzyTmata wrote: we just had a 4.7 in northern New Jersey. we felt a low rumble here in South Jersey. Our house was shaking here just north of your border.

JrzyTmata

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Posted: Apr 5, 2024 - 7:41am
we just had a 4.7 in northern New Jersey. we felt a low rumble here in South Jersey.

NoEnzLefttoSplit

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Posted: Mar 23, 2023 - 1:13pm

geoff_morphini wrote:

Sort of my feeling about Bard's response. Could have asked the same for the US west coast.

Ignimbrite flare-up - I'd like to see that paper. The IFU the western US experienced (ca. 20-30 Ma) was due to the Farallon slab collapsing into the mantle and really hot asthenospheric material contacting continental crust...boom!

As to the question about future prospects of the diminishing Alpine fault, I don't know. I'll have to look for another example of opposed polarity subduction zones mating.

It is definitely geology on steroids in Aotearoa

I guess that is a band name

I'll try and find that paper for you. I think it was from this year.

geoff_morphini

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Posted: Mar 23, 2023 - 1:08pm

NoEnzLefttoSplit wrote:

ha, interesting what that punches out. Basically very bland.
The most recent paper I read is that NZ is currently in the middle or even beginnings of an ignimbrite flare-up so I wouldn't go with relative stability, unless you take some ridiculously short time-frame for geological processes. The rest is pretty mundane stuff that could apply just about anywhere on the Pacific rim.
The actually reality is that NZ geology is scary as all hell but equally fascinating.

Sort of my feeling about Bard's response. Could have asked the same for the US west coast.

Ignimbrite flare-up - I'd like to see that paper. The IFU the western US experienced (ca. 20-30 Ma) was due to the Farallon slab collapsing into the mantle and really hot asthenospheric material contacting continental crust...boom!

As to the question about future prospects of the diminishing Alpine fault, I don't know. I'll have to look for another example of opposed polarity subduction zones mating.

It is definitely geology on steroids in Aotearoa

NoEnzLefttoSplit

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Posted: Mar 23, 2023 - 12:18pm

miamizsun wrote:

thank you bard!

New Zealand is located in the Pacific Ring of Fire, a region of intense volcanic and seismic activity. The country is currently experiencing a period of relative stability, but this is expected to change in the future.

Over the next million years, New Zealand is expected to experience a number of tectonic events, including:

Earthquakes: New Zealand is currently experiencing a number of earthquakes each year, and this number is expected to increase in the future. The largest earthquakes in New Zealand are capable of causing significant damage and loss of life.
Volcanic eruptions: New Zealand is also home to a number of volcanoes, and these volcanoes are expected to erupt in the future. Volcanic eruptions can cause significant damage and loss of life, as well as release harmful gases into the atmosphere.
Tsunamis: New Zealand is also located in an area that is prone to tsunamis. Tsunami waves can cause significant damage and loss of life, as well as inundate coastal areas.

These tectonic events are a natural part of the Earth's evolution, but they can also pose a significant threat to the people and infrastructure of New Zealand. It is important to be aware of the risks associated with these events and to take steps to mitigate them.

There are a number of things that can be done to mitigate the risks associated with tectonic events in New Zealand. These include:

Building codes: Building codes in New Zealand are designed to withstand earthquakes and other tectonic events. These codes can help to reduce the damage caused by these events.
Emergency plans: New Zealand has a number of emergency plans in place to deal with the aftermath of tectonic events. These plans can help to reduce the loss of life and property.
Education: It is important to educate the people of New Zealand about the risks associated with tectonic events and how to stay safe. This education can help to reduce the impact of these events.

miamizsun

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Posted: Mar 23, 2023 - 12:00pm

NoEnzLefttoSplit wrote:

not really a triple junction is it? what is going to happen here over the next million years or so do you think? You basically have two slabs subducting in opposite directions racing towards each other obliquely on strike-slip fault (albeit with a bit of horizontal movement tossed in). The bit in the middle is obviously going to be deformed every which way to Sunday, (it already is) but sooner or later those subducting slabs are going to meet each other at depth. What happens then? Do they stick? Will some kind of transform fault form and one of the plates start subducting somewhere else? Are there any precedents for this kind of thing? sorry, lots of questions, I know., but it is hard to envisage.

thank you bard!

Over the next million years, New Zealand is expected to experience a number of tectonic events, including:

Earthquakes: New Zealand is currently experiencing a number of earthquakes each year, and this number is expected to increase in the future. The largest earthquakes in New Zealand are capable of causing significant damage and loss of life.
Volcanic eruptions: New Zealand is also home to a number of volcanoes, and these volcanoes are expected to erupt in the future. Volcanic eruptions can cause significant damage and loss of life, as well as release harmful gases into the atmosphere.
Tsunamis: New Zealand is also located in an area that is prone to tsunamis. Tsunami waves can cause significant damage and loss of life, as well as inundate coastal areas.

There are a number of things that can be done to mitigate the risks associated with tectonic events in New Zealand. These include:

Building codes: Building codes in New Zealand are designed to withstand earthquakes and other tectonic events. These codes can help to reduce the damage caused by these events.
Emergency plans: New Zealand has a number of emergency plans in place to deal with the aftermath of tectonic events. These plans can help to reduce the loss of life and property.
Education: It is important to educate the people of New Zealand about the risks associated with tectonic events and how to stay safe. This education can help to reduce the impact of these events.

NoEnzLefttoSplit

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Posted: Mar 23, 2023 - 11:51am

geoff_morphini wrote:

That is a top notch crew of authors, know many of them really well. It is certainly not a simple plate boundary.

geoff_morphini

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Posted: Mar 23, 2023 - 9:34am
NoEnzLefttoSplit wrote: what a train wreck 3d map of NZ's fault systems That is a top notch crew of authors, know many of them really well. It is certainly not a simple plate boundary.

NoEnzLefttoSplit

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Posted: Mar 23, 2023 - 3:50am
what a train wreck 3d map of NZ's fault systems

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