Earthquakes around the world

[Pierre]

Yes, for a same magnitude a shallow quake will be more destructive than a deep one, also the Richter scale only measures intensity. The total power of a quake is equal to its magnitude multiplied by its duration, so for a same magnitude a short quake will be less destructive than a long one.

Those 'moderate' quakes leading to substantial destruction are probably shallow and long lasting.

According to article bellow: "how long an earthquake lasts is a decent proxy for its magnitude"

One single parameter (wave amplitude measured by sismographs during the first seconds) reflects part of a very complex seismic phenomenon. It is a decent proxy but does it tell the whole story? Does it tell the true story? Shoji et al. have actually tested the correlation between quakes magnitude, power and duration. Here are two of their result charts:

As you can see in the left chart, for a same magnitude, say M5.0, duration ranges between 5 and 30 seconds. More impressive is the right chart where for a same magnitude, say M5.0, the power ranges between 5 and 600!

Several factors explain those 'deviations' among which rupture length, generated frequencies and type of soil. Richter was aware of those factors (at least some of them) and his original scale held only for California earthquakes occurring within 600 km of a particular type of seismograph.

Another factor that contributes to 'deviations' relates to the way amplitudes are measured:

Problems with Magnitude Scales

There are several problems associated with using magnitude to quantify earthquakes, and all are a direct consequence of trying to summarize a process as complex as an earthquake in a single number. First, since the distance corrections depend on geology each region must have a slightly different definition of local magnitude. Also, since at different distances we rely on different waves to measure the magnitude, the estimates of earthquake size don't always precisely agree. Also, deep earthquakes do not generate surface waves as well as shallow earthquakes and magnitude estimates based on surface waves are biased low for deep earthquakes.

Also, measures of earthquake size based on the maximum ground shaking do not account for another important characteristic of large earthquakes - they shake the ground longer. Consider the example shown in the diagram below. The two seismograms are the P-waves generated by magnitude 6.1 and 7.7 earthquakes from Kamchatka. The body-wave magnitude for these two earthquakes is much closer because the rule for estimating body-wave magnitude is to use the maximum amplitude in the first five seconds of shaking. As you can see, the difference in early shaking between the two earthquakes is much less than the shaking a little bit later which indicates the larger difference in size.
Short-Period Saturation

Teleseismic (distant) P-waves generated by two earthquakes in Kamchatka and recorded at station CCM, Cathedral Caves, MO, US. The signals that would be recorded on a on a short-period seismometer are shown using the same scale. The time is referenced to the onset of rupture for each earthquake.

Even after 5 seconds the amplitude ratio of these P waves does not accurately represent the difference in size of these two earthquakes. The magnitude 6.1 event probably ruptured for only a few seconds, the magnitude 7.7 ruptured for closer to a minute.

Source.

So for a same magnitude a quake that is shallow, in conducting/resonating ground, grows stronger after the first few seconds, lasts longer than average and involves a longer rupture line will be substantially more powerful.

 

[Laura]

I was wondering if that impact on Jupiter recently could have had some EM effects on Earth and thereby contributing to EQ activity?

 

[Human]

Thank you Pierre for elaborate reply, I can see now that relationship between tremor duration and it's magnitude is much more complex that simple proportionality.

What I wanted to point out is that duration and magnitude are not really independent variables to be used to calculate total power as their product, and I don't see that relationship
total power (P) = duration (D) x magnitude (M)
is denoted anywhere in the quoted paper [Shoji et al.].

In addition, in that paper, it seems to me that P and D are used as independent, non-correlated parameters in describing earthquakes. Although the duration is by definition time interval in which earthquake released from 5% to 95% of it's total (cumulative) power.
In abstract we read:

[...]
For the total power and rms amplitude, the difference at each site exceeds the variability at each event, and strong site-dependency was found. The variability for the total power, rms amplitude and peak ground acceleration (PGA) indicated essentially the same trends. On the other hand, it is quantitatively revealed that the event-dependency for the duration is greater than the site-dependency.
[...]

Unfortunately, among the plots in the article, there is no P vs. D one, but you said it yourself:

As you can see in the left chart, for a same magnitude, say M5.0, duration ranges between 5 and 30 seconds. More impressive is the right chart where for a same magnitude, say M5.0, the power ranges between 5 and 600!

The differences in range/spread of points and shape shown on those two plots do not suggest simple P=DxM, which is even more strongly pronounced when comparing Fig. 14 and Fig. 15.
I mean, just check the highest D points for given M quakes on Fig. 5 and 6 -> on P vs M plot those points (triangles) appear way down at the bottom of the column, suggesting that for same M longest duration quakes released lowest total power P, conclusion which is in obvious contradiction to P=DxM relationship.

 

[Pierre]

What I wanted to point out is that duration and magnitude are not really independent variables to be used to calculate total power as their product, and I don't see that relationship
total power (P) = duration (D) x magnitude (M)
is denoted anywhere in the quoted paper [Shoji et al.]

.

You're right. The P=D X M relation was a way to convey that, independently from the magnitude of a quake and although magnitude and duration are partly related, its duration has an influence on the total energy released.

You also have to specify a duration of shaking over a given level. We can actually detect the shaking from the very largest earthquakes for weeks after they occur but no one would say that they felt it for that long.
Source

In this sense you can have two earthquakes of the same magnitude while one of them exhibits a lot of activity below a given level, its official duration might be therefore the same but its actual duration is longer, thus it generates more energy (more destructive)

the damage to a given structure will depend both on the amplitude of the shaking and its duration. How to best combine these quantities into an estimate of the amount of damage is ongoing research.

Source

The exact equation combining duration and magnitude is indeed ongoing research.

 

[Mr.Cyan]

I guess if 4D STS or the Information Field wanted to really smack down the human race for being so greedy and bloodthirsty, that would sure be one way to do it. As to whether it is in the power of any human beings to do that... who might actually consider doing it.... I don't know.

Thanks Laura for the interesting information. Giving it some thought, I think like the Sott editors comment in the excellent Sott article linked below (by J. Hagopian), the earthquake and volcanic activity is more likely cosmic related. However, when considering all the info related to "earthquake inducing weaponry" I wouldn't be surprised, if the 4D STS'ers try to "slip in " their version of earthquakes in the times to come, for nothing other than to cause more chaos...sort of an enhanced negative emotions feeding frenzy for them....sigh!

http://www.sott.net/article/316605-Multiple-recent-powerful-earthquakes-reflect-a-planet-in-deep-transition

 

[thorbiorn]

What I wanted to point out is that duration and magnitude are not really independent variables to be used to calculate total power as their product, and I don't see that relationship
total power (P) = duration (D) x magnitude (M)
is denoted anywhere in the quoted paper [Shoji et al.]

.

You're right. The P=D X M relation was a way to convey that, independently from the magnitude of a quake and although magnitude and duration are partly related, its duration has an influence on the total energy released.

You also have to specify a duration of shaking over a given level. We can actually detect the shaking from the very largest earthquakes for weeks after they occur but no one would say that they felt it for that long.
Source

In this sense you can have two earthquakes of the same magnitude while one of them exhibits a lot of activity below a given level, its official duration might be therefore the same but its actual duration is longer, thus it generates more energy (more destructive)

[...]

Below are examples of two differnt kinds of earthquakes, fast and slow: Slow earthquake

Seismologists characterized it as a slow earthquake due to disproportionately large tsunami waves, rupture duration near 125 seconds, shallow near-trench slip, and deficiencies in energy.

Every five years a year-long quake of this type occurs beneath the New Zealand capital, Wellington. It was first measured in 2003, and has reappeared in 2008 and 2013.[11] It lasts for around a year each time, releasing as much energy as a magnitude 7 quake.

Lasting for a year the damage is overall less. But there are also some that have fast waves:

A supershear earthquake is an earthquake in which the propagation of the rupture along the fault surface occurs at speeds in excess of the seismic shear wave (S-wave) velocity. This causes an effect analogous to a sonic boom.[1]
[...]
Rupture propagation velocity

During seismic events along a fault surface the displacement initiates at the focus and then propagates outwards. Typically the focus lies towards one end of the slip surface and much of the propagation is unidirectional (e.g. the 2008 Sichuan and 2004 Indian Ocean earthquakes). Theoretical studies have in the past suggested that the upper bound for propagation velocity is that of Rayleigh waves, approximately 0.92 of the shear wave velocity.[2] However, evidence of propagation at velocities between S-wave and compressional wave (P-wave) values have been reported for several earthquakes[3][4] in agreement with theoretical and laboratory studies that support the possibility of rupture propagation in this velocity range.[5][6]

The velocity of the Rayleigh wave? There is this:

Rayleigh waves have a speed slightly less than shear waves by a factor dependent on the elastic constants of the material.[1] The typical speed of Rayleigh waves in metals is of the order of 2–5 km/s, the typical Rayleigh speed in the ground is of the order of 50–300 m/s. Since Rayleigh waves are confined near the surface, their in-plane amplitude when generated by a point source decays only as {1}/{\sqrt{r}}, where r is the radial distance. Surface waves therefore decay more slowly with distance than do bulk waves, which spread out in three dimensions from a point source.
[...]

On SOTT there have been a couple of articles about fast waves: http://www.sott.net/article/262535-Earthquakes-that-break-seismic-sound-barrier-confirmed-in-lab-experiments and

The shaking provided the first sign that this was a strange quake. Earthquakes of similar size, such as the 1994 Northridge quake in Los Angeles, shimmy for seven to eight seconds. But this magnitude-6.7 temblor lasted for just two seconds.

After dredging up all the available seismic recordings, Zhan and his co-authors realized the earthquake was extremely short because it was extremely fast.

An earthquake occurs when two sides of a fault rip apart, opening up like a zipper. Faults can slide side-by-side or up-and-down, or a combination of both directions. The event unleashes waves of seismic energy. Certain types of waves called shear waves usually travel faster than the rupture unzips, but in supershear earthquakes, the rupture catches the shear waves.

When the rupturing fault moves faster than the shear waves, the waves of energy pile up like the Mach cone surrounding a jet flying faster than the speed of sound, creating a phenomenon akin to a seismic sonic boom.

The Okhotsk quake's rupture speed clocked in at a zippy 5 miles per second (8 km/s), said Zhan, a seismologist at the Scripps Institution of Oceanography in La Jolla, California. Regular earthquakes, at shallower depths, break loose at about 2.2 miles per second (3.5 km/s), he said.

In a supershear earthquake, however, the shear waves are created very quickly when a long fault, like the San Andreas, breaks loose faster than the speed shear waves normally travel. When this happens the shear waves mach cone is created that can reach the same speed as the pressure waves, explained the paper's lead author, François Passelègue of the Geology Laboratory at École Normale Supérieure in Paris, France.

"The main additional hazard due to supershear earthquakes is that there are two big wave arrivals," Passelègue told Discovery News. To someone riding out such a quake, the first thing to arrive would be the sharp pressure wave, but instead of the rolling shear waves following it, the powerful supershear mach cone would arrive and shake the ground in a direction parallel to the fault zone that created it. Then, soon after, a second shear wave would hit with ground motions at right angles to the fault zone. "This sudden change in the direction of the dominant ground motions is dramatic for buildings."

There are sveral sites about earthquakes fx.

http://web.ics.purdue.edu/~braile/edumod/waves/WaveDemo.htm has a simulation for different wave types.
http://sunshine.chpc.utah.edu/Labs/SeismicWaves/seismic.swf shows how waves travel through and over the planet.
Regarding the relation between quake size and damage the following notes:

Surface waves are very similar to ocean waves as they only occur at the surface of the earth and do not penetrate into the interior deeply. There are two types of surface waves: Love waves and Rayleigh waves. Typically, it the surface waves that do the most damage during an earthquake, especially at distances far from the epicenter. Most of the damage in the 1985 Mexico City earthquake was from surface waves that had traveled over 200 kilometers from the epicenter located near the west coast of Mexico. The velocity of surface waves varies with their wavelength but always travel slower than P and S waves.
[...]
Soft sediment and sand tends to amplify seismic waves and create more shaking (and consequently damage).

The above page has annimations that show how different waves move and how they combine in an earthquake.

On http://sunshine.chpc.utah.edu/Labs/SeismicWaves/ there is also one simulation where one can adjust the density of the medium and find out, how this affects the movement of the material. Solid rock has a higher density than wet packed sand or clay and would behave differently. One can also see from movies of landslides how the soil moves more like a thick liquid than like a solid.

 

[Gawan]

There happened a minor quake in Bulgaria today on the scale of 4.2 (USGS 4.5), so far no damages or injuries are reported.

An earthquake was registered on April 18 near the town of Nova Zagora in southern Bulgaria. Initial preliminary reports on the magnitude of the quaked ranged from 4.2 on the Richter scale from the Bulgarian Academy of Sciences, as quoted by Focus News agency, to 4.4 from the European-Mediterranean Seismological Centre (EMSC) and 4.5 from the US Geological Survey (USGS).

The quake occurred at 9.46am local time, or 6.46am UTC, with the epicentre reported at seven km south-east of Nova Zagora by EMSC and three km north-east of Nova Zagora by USGS. The two reports also differed on the depth of the quake, which EMSC put at two km and USGS at 16.5km.

Local media said that residents there were no immediate reports of injuries or damage. Private broadcaster Darik quoted the mayor of Nova Zagora, Nikolai Grozev, as saying that the quake was felt strongly, but was a brief one.

http://sofiaglobe.com/2016/04/18/earthquake-of-at-least-4-2-on-richter-scale-near-bulgarias-nova-zagora/

Also interesting to note is the following article imo (in relation to what Windmill knight already stated):

Are we paying attention? 3 volcanoes erupt simultaneously on April 16, 2016: Villarrica (Chile), Mt. Cleveland (USA), Colima (Mexico)

 

[Lilou]

http://jordantimes.com/news/local/39-magnitude-earthquake-recorded-dead-sea-area

AMMAN — An earthquake with a magnitude of 3.9 on the Richter scale hit Lisan in the Dead Sea area on Friday, according to the Jordan Seismological Observatory (JSO).

JSO Director Mahmoud Qariouti said an earthquake hit the Lisan area at 7:15am on Friday, at a depth of 8km, preceded by another quake that hit the same area at around 9:35pm on Thursday, which measured 3.1 degrees on the Richter scale.

No damages or casualties were recorded, the Jordan News Agency, Petra, reported.

During the last few months, southern regions have witnessed several earthquakes.

In February, an earthquake hit Wadi Araba area and measured 4 degrees on the Richter scale.

Jordan lies along the seismically active Dead Sea Transform Fault, with estimates predicting a major earthquake every 100 years.
- See more at: http://jordantimes.com/news/local/39-magnitude-earthquake-recorded-dead-sea-area#sthash.2YF5s0Ch.dpuf

 

[Chad]

There happened a minor quake in Bulgaria today on the scale of 4.2 (USGS 4.5), so far no damages or injuries are reported.
[...]

Also interesting to note is the following article imo (in relation to what Windmill knight already stated):
[...]

Also of note: yesterday there was an earthquake in Greenland yesterday - apparently the last near this magnitude was 4 months ago

Magnitude : 4.5

Aasiaat, [Western] Greenland

Local Time (conversion only below land) : 2016-04-17 14:17:18

GMT/UTC Time : 2016-04-17 16:17:18

Depth (Hypocenter) : 15.03 km

Depth and Magnitude updates in the list below.

I saw it on the USGS but it's dropped off now:

SRC Location UTC Date/time M D INFO
USGS Aasiaat, Greenland Apr 17 16:17 4.5 15 MAP I Felt It INFO
EMSC Western Greenland Apr 17 16:17 4.5 2 MAP I Felt It INFO
GEOFON Western Greenland Apr 17 16:17 4.5 10 MAP I Felt It INFO

And a selected few from today and one from yesterday:

4.7 144km NNW of Bamboo Flat, India 2016-04-18 15:29:55 UTC 38.4 km

5.1 38km NNE of Bahia de Caraquez, Ecuador 2016-04-18 13:25:44 UTC 10.0 km

5.9 19km WNW of Isangel, Vanuatu 2016-04-18 13:06:09 UTC 65.8 km

5.1 131km NNE of Bristol Island, South Sandwich Islands 2016-04-17 19:33:46 UTC 59.4 km

 

[casper]

"Unusual quake cluster worries Japan",link:
http://asia.nikkei.com/Features/Kyushu-earthquakes/Unusual-quake-cluster-worries-Japan


"Seismic activity stretched 100 kilometers",link:
http://newsonjapan.com/html/newsdesk/article/116001.php
"According to a calculation by Masashi Omata of the Japanese Society for Active Fault Studies, the ground here moved about 20 centimeters vertically, and about two meters horizontally. This measurement was taken in a northeastern section of the Futagawa fault zone, which extends for at least about 64 kilometers. "Part of the Futagawa fault zone shifted and caused the magnitude-7.3 temblor," Omata said. "


"GPS data indicates shifting land surface",link.
http://newsonjapan.com/html/newsdesk/article/115991.php



F-E Region: South Sandwich Islands Region
Mw Beach Ball
Time: 2016-04-19 05:25:41.1 UTC
Magnitude: 6.2 (Mw)
Epicenter: 27.36°W 55.72°S
Depth: 10 km
Status: C - confirmed
http://geofon.gfz-potsdam.de/eqinfo/event.php?from=rss&id=gfz2016hroo

 

[casper]

M5.1 - 3km WNW of Yatsushiro, Japan
http://earthquake.usgs.gov/earthquakes/eventpage/us20005jr8#general

 

[Laura]

I don't know where else to put this very curious thing. It MAY have something to do with earthquakes or weather or whatever.

Curious: A Total Solar Irradiance nosedive seen in SORCE data
Anthony Watts / 2 hours ago April 19, 2016
https://wattsupwiththat.com/2016/04/19/curious-a-total-solar-irradiance-nosedive-seen-in-sorce-data/

I don’t know if this is a real measurement, and that the Total Solar Irradiance (TSI) measured by the SORCE project is real, or if we are seeing another sensor failure situation like what happened with NSIDC and the sea-ice measurements done by DMSP F17 satellite.

Yesterday this graph of TSI plotted by SORCE was brought to my attention by WUWT reader Stephen Shochat:

The value on April 11th was about 1360.45 watts/m² by far the lowest in three months

I emailed our resident solar physicist, Dr. Leif Svalgaard, but got no reply, he may be traveling or may have thought it not noteworthy. Today I checked the graph again, thinking perhaps a correction might have been made if there was a calibration or instrument error, there was none, and the TSI value decreased further, to about 1360.25 watts/m²

A look at the sun itself suggests it may simply be due to a very, very, large sunspot rotating through the Earth-View. My guess is we’ll see a rebound in TSI once it crosses the horizon. Occam’s Razor.

If nothing else, this demonstrates that sunspots can have quite a large, if only temporary, forcing on TSI and Earth’s received energy budget.

 

[Mikey]

I don't know where else to put this very curious thing. It MAY have something to do with earthquakes or weather or whatever.

It's pretty low (1360.2 W/m² right now, lower than during solar minimum), but spikes like that have apparently happened before. Here's the graph over the last 18 Years, from http://lasp.colorado.edu/home/sorce/data/tsi-data/

 

[Chad]

M 5.0 Earthquake
14km ENE of Santa Maria, Philippines
An earthquake with magnitude 5.0 occurred near Hinatuan, Mindanao, Philippines at 17:17:36.80 UTC on Apr 19, 2016 ...

1 hour ago · Sources: U.S. Geological Survey, ready.gov

 

[mkrnhr]

I don't know where else to put this very curious thing. It MAY have something to do with earthquakes or weather or whatever.

It's pretty low (1360.2 W/m² right now, lower than during solar minimum), but spikes like that have apparently happened before. Here's the graph over the last 18 Years, from http://lasp.colorado.edu

It could be due to the large sunspot of last week (although they are usually compensated by bright faculae) or something else. However, the Sun is definitively not behaving as before as one can see from the following presentation: _http://www.leif.org/research/Non-Conforming-SC24.pdf

Conclusion
Cycle 24 is behaving differently from previous cycles:
- CME frequency too high
- TSI too high
- Magnetic field too high [at least since 2014]