M 7.7 quake Mariana Isl .... NOW

  • Thread starter davenn
  • Start date
In summary, the P was is quite large on my seismo ... surface waves haven't arrived yet (0739 AEST 2139 UT). There is no tsunami warning or watch in effect at this time.
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  • #2
7.7 is a lot. Is there a tsunami expected? A link to a news page?
 
  • #3
fresh_42 said:
7.7 is a lot. Is there a tsunami expected? A link to a news page?

I linked to the USGS and to my page
news pages are unreliable and never give the correct info ... they probably don't even know the event has happened

there's no tsunami warning or watch in effect at this time
 
  • #4
I'm simply not bright enough to translate the figures into imagination. One map shows a settlement only a few hundred km away.
And the amount of water above 212 km sounds dangerous. At least as long as one doesn't know the direction of movement.
 
  • #5
fresh_42 said:
One map shows a settlement only a few hundred km away

which map ? link ?

fresh_42 said:
And the amount of water above 212 km sounds dangerous.

not sure what you mean by this ?
Dave
 
  • #7
fresh_42 said:
You're right. I misread the units. I thought it was closer to the surface. My fault.

the 212km is the depth below the surface that the focal point of the quake is ( doesn't include sea depth if event is at sea like this one)

initially it was listed at 188km deep. and knowing the location, it's easy to realize that it is a subduction event.
In that area, the Pacific Plate seafloor is diving down under the Philippine Plate

One thing that will probably be noticed over the next 24 hours is that there is unlikely to be many aftershocks.
This is common with deep events, even large ones. If it was a shallow (crustal event, 0 - 30km deep) then there would be 100's
to 1000's of aftershock recorded. I will be surprised if there is anything more than a few 10's of aftershocks recorded, if that.
Dave
 
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  • #8
OK here's the raw seismogram

160729   UT M7.7 nthern Marianas zhi.gif
 
  • #9
Just for background, "The Challenger Deep in the Mariana Trench is the deepest known point in Earth's oceans. In 2010 the United States Center for Coastal & Ocean Mapping measured the depth of the Challenger Deep at 10,994 meters (36,070 feet) below sea level with an estimated vertical accuracy of ± 40 meters," according to Geology.com. That's at most 11 km.
http://geology.com/records/deepest-part-of-the-ocean.shtml
http://www.deepseachallenge.com/the-expedition/mariana-trench/

The deeper the earthquake, the less likely a tsunami.

The 2011 earthquake off the Pacific coast of Tōhoku was a 9.0 magnitude (Mw) undersea megathrust earthquake occurred on 11 March 2011 at 14:46 JST (05:46 UTC) in the north-western Pacific Ocean at a relatively shallow depth of 32 km (19.9 mi), with its epicenter approximately 72 km (45 mi) east of the Oshika Peninsula of Tōhoku, Japan, lasting approximately six minutes.
https://en.wikipedia.org/wiki/2011_Tōhoku_earthquake_and_tsunami
http://earthquake.usgs.gov/earthquakes/eqarchives/poster/2011/20110311.php [Broken]
http://earthquake.usgs.gov/earthquakes/eqinthenews/2011/usc0001xgp/#details [Broken] (page may be discontinued in the future)
https://www.ngdc.noaa.gov/hazard/11mar2011.html

Much of the Pacific Ocean is about 5-6 km deep.
http://oceansjsu.com/105d/exped_mapping/13a.html
 
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  • #10
and a processed seismogram with data

160729.212010.zhi.gif.gif
 
  • #11
Thanks for sharing @davenn . Is there a layman explanation of how the data reduction from raw to processed works?
 
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  • #12
anorlunda said:
Thanks for sharing @davenn

you are welcome ... one of my loves in life :smile:

anorlunda said:
Is there a layman explanation of how the data reduction from raw to processed works?

ohhh ... where do I start ?

firstly, I didn't write the software or design the hardware for my system. Credit for that goes to Larry Cochrane from California
who was one of the original members of the PSN ( Public Seismic Network) in the USA.
http://psn.quake.net/

He designed 2 significant pieces of hardware a multi-channel preamp that goes between the sensors and the ADC data logger.
And the datalogger with its assoc software WinSDR (Windows Seismic Data Recorder)

preamp ... http://psn.quake.net/serialamp.html

ADC/Datalogger ... http://psn.quake.net/serialatod.html

WinSDR ... http://psn.quake.net/software.html#WinSDR

The raw seismogram you see in post #8 is a screenshot of the display on the WinSDR datalogging PC
currently I am using a Dell ( about 3 years old) and running Win7. This PC runs 24/7.

The analysis software that is on my main PC, for loading in and producing the final data file as seen in post #10
is called WinQuake ... http://psn.quake.net/software.html#WinQuake

WinQuake, along with the hardware and WinSDR have gone through many upgrades since its initial release in the early
- mid 1990's ( My station went digital in 1996)

have a read through some of the documentation in the links
hopefully it will answer most of your questions :smile:Regards
Dave
 
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  • #13
davenn said:
firstly, I didn't write the software or design the hardware for my system. Credit for that goes to Larry Cochrane from California
who was one of the original members of the PSN ( Public Seismic Network) in the USA.
http://psn.quake.net/
Very cool links and sites, thanks for posting them. I noticed when I used the link to your homepage that it came up blank, I know your site is up and running as I was looking at it yesterday, maybe the psn.quake site has a broken link to you ?o_O
 
  • #14
1oldman2 said:
I noticed when I used the link to your homepage that it came up blank, I know your site is up and running as I was looking at it yesterday, maybe the psn.quake site has a broken link to you ?

yeah, the link on Larry's home page for my site is long out of date, he hasn't got around to updating it

just bookmark my homepage

http://www.sydneystormcity.com/cheers
Dave
 
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1. What is a "M 7.7 quake"?

A "M 7.7 quake" refers to a magnitude 7.7 earthquake, which is a measurement of the energy released during an earthquake. It is calculated using the Richter scale, with each whole number increase representing a tenfold increase in magnitude.

2. Where are the Mariana Islands located?

The Mariana Islands are a group of islands located in the western Pacific Ocean, east of the Philippines and north of Guam. They are a part of the Mariana Arc, a volcanic chain of islands formed by the subduction of the Pacific Plate beneath the Philippine Sea Plate.

3. What caused the "M 7.7 quake" in the Mariana Islands?

The "M 7.7 quake" in the Mariana Islands was likely caused by the movement of tectonic plates. The Mariana Arc is an area of intense seismic activity due to the subduction of the Pacific Plate beneath the Philippine Sea Plate. This movement can result in earthquakes, volcanic eruptions, and tsunamis.

4. How does a "M 7.7 quake" impact the environment?

A "M 7.7 quake" can have devastating impacts on the environment. It can cause landslides, tsunamis, and changes in the topography of the affected area. It can also disrupt ecosystems and affect wildlife. Human activities can also be affected, such as infrastructure damage and displacement of communities.

5. Is there a way to predict when a "M 7.7 quake" will occur?

Currently, there is no way to accurately predict when a "M 7.7 quake" or any earthquake will occur. However, scientists use seismographs and other technology to monitor seismic activity and understand the patterns of earthquakes in a specific region. This can help to identify areas that are at a higher risk for earthquakes and inform preparedness and response efforts.

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