What Caused the Recent Earthquakes in the SW Pacific Region?

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In summary: KHz.In summary, 3 large quakes (6.5, 6.9, 6.3) have occurred in the SW Pacific area in the past 24 hours. A sixth (6.9) magnitude quake occurred near L'Esperance Rock in New Zealand.
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davenn
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Hi guys

the last 24 hours has seen 3 large quakes in the SW Pacific area

6.5 central Solomon Isl. not far from Kirakira
M 6.5 - 65km NW of Kirakira, Solomon Islands

6.9 southern Kermadec Isl. area
M 6.9 - 61km SW of L'Esperance Rock, New Zealand

6.3 Loyalty Isl area E of New Caledonia
M 6.3 - 202km WNW of Ile Hunter, New Caledonia

the recording from my seismo system
http://www.sydneystormcity.com/seismograms.htm

180909-10  UT M 6.5 Solomons, 6.9 Kermadecs, 6.3 Loyalty Isl zhi.gif
cheers
Dave
 

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@davenn Just a point of clarification for us ignorant types, please. Suppose two unrelated seismic events are concurrent, i.e., overlapping in time. Using the seismic graph, how can you differentiate them?
 
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jim mcnamara said:
Suppose two unrelated seismic events are concurrent, i.e., overlapping in time. Using the seismic graph, how can you differentiate them?

OK this does happen from time to time, actually reasonably regularly.
Mainly with a large event with one or more aftershocks buried in the larger events' signal. I personally haven't been able to see,
say a, M5.5 aftershock that is buried in the M7.2 mainshock if they have occurred within a minute of each other.

here's a recent example ….
Main shock
M 8.2 - 286km NNE of Ndoi Island, Fiji
2018-08-19 00:19:40 (UTC)

Aftershock
M 6.3 - 268km NNE of Ndoi Island, Fiji
2018-08-19 00:23:06 (UTC)

On my recording, I couldn't tell that there were 2 events separated by ~ 4 minutes. But the experts could :smile:

upload_2018-9-12_13-18-4.png
How they do it, I am not sure. Maybe I need to send some emails and see if they will tell me. :biggrin:

Now for the same or closely times events that are separated by some distance, then it becomes easy to differentiate the events using a seismograph network.
as there will always be one or more sensors in the network that are closer to one of those 2 events that what the other sensors are.
It then just becomes a matter of the timing of the P wave arrivals at the various network sensors from which they can then produce locations for the events.hope that helps

Dave
 

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OK with a bit of playing around with filtering. Mainly doing high pass filtering so I could cut out a large portion of the
lower frequency signals. This helps the P wave arrivals from both events to stand out clearer.
I did a 6 pole hi-pass filtered from 1Hz

P arrivals.JPG
 

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Related to What Caused the Recent Earthquakes in the SW Pacific Region?

1. What is seismology?

Seismology is the scientific study of earthquakes and the propagation of elastic waves through the Earth or through other planet-like bodies.

2. How does seismology contribute to our understanding of earthquakes?

Seismology helps us learn about the characteristics of earthquakes, such as their location, magnitude, and frequency. It also provides valuable information about the Earth's interior and the processes that cause earthquakes.

3. What tools and techniques are used in seismology?

Some common tools and techniques used in seismology include seismometers, which measure ground motion, and seismographs, which record ground motion. Other techniques include seismic reflection, refraction, and tomography, which use seismic waves to image the Earth's interior.

4. How do seismologists monitor and track earthquakes?

Seismologists use a network of seismometers to monitor and track earthquakes. These instruments record ground motion and send data to a central location for analysis. Advanced technology, such as GPS and satellite imagery, also help seismologists track earthquakes.

5. How does seismology help with earthquake prediction and mitigation?

While seismology cannot predict earthquakes with certainty, it can provide valuable information for earthquake hazard assessment and risk reduction. By understanding the behavior of earthquakes and the Earth's structure, seismologists can help communities prepare for and mitigate the impact of future earthquakes.

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