Earthquakes around the world

[mabar]

I have a friend that felt a tremor, he told me very big, in North Spain, in Catalonia, today.

Did not saw it at USGS website nor in spaniards newspapers so far. Could that be the kind of tremor due to other circumnstances as registered in other countries?.

 

[loreta]

I have a friend that felt a tremor, he told me very big, in North Spain, in Catalonia, today.

Did not saw it at USGS website nor in spaniards newspapers so far. Could that be the kind of tremor due to other circumnstances as registered in other countries?.

I really don't know. I don't live in that region. Another person, in FB, said that her house was trembling. I will ask him again.

Ok, another catalan confirmed that there was a earthquake on Mataró, the city where they live. A adjunt a link that he put:

http://realtimetools.de/

 

[David Topi]

I have a friend that felt a tremor, he told me very big, in North Spain, in Catalonia, today.

Did not saw it at USGS website nor in spaniards newspapers so far. Could that be the kind of tremor due to other circumnstances as registered in other countries?.

I really don't know. I don't live in that region. Another person, in FB, said that her house was trembling. I will ask him again.

Ok, another catalan confirmed that there was a earthquake on Mataró, the city where they live. A adjunt a link that he put:

http://realtimetools.de/

yes, this one in mataro is the one i have seen in the news, but it was just a 2.9 so i do not know if this is the one you refer to. I live about 30km from mataro (it is very close to bcn) and did not feel anything.

 

[loreta]

I have a friend that felt a tremor, he told me very big, in North Spain, in Catalonia, today.

Did not saw it at USGS website nor in spaniards newspapers so far. Could that be the kind of tremor due to other circumnstances as registered in other countries?.

I really don't know. I don't live in that region. Another person, in FB, said that her house was trembling. I will ask him again.

Ok, another catalan confirmed that there was a earthquake on Mataró, the city where they live. A adjunt a link that he put:

http://realtimetools.de/

yes, this one in mataro is the one i have seen in the news, but it was just a 2.9 so i do not know if this is the one you refer to. I live about 30km from mataro (it is very close to bcn) and did not feel anything.

Yes,it is this one, very low but it seems that many people felt it. I have another link to check for earthquakes for Calalonia, this is for the 11 April but if you look for today, there was a movement too. Very interesting page!

http://www1.igc.cat/web/ca/sismologia_sismograma.php?dia=20120411&est=COBS

So...You are you catalan (like me? :) )

 

[caballero reyes]

Earthquake 6.8 and five minor replicas last night in state capital and beaches of Sonora.The first time I feel an earthquake,¡t was scary.

 

[mabar]

Yes,it is this one, very low but it seems that many people felt it. I have another link to check for earthquakes for Calalonia, this is for the 11 April but if you look for today, there was a movement too. Very interesting page!

http://www1.igc.cat/web/ca/sismologia_sismograma.php?dia=20120411&est=COBS

That's right, and I think I already know why I did not found it, mostly due to … terminology, I made a search with “temblor” (earth tremor) word, not “terremoto”(earthquake), to me “terremoto” word is more related to destruction.

It is an interesting website, and I found there was another one in the same region yesterday. And still did not appear in USGS website, must be related measurement issues between countries.
http://www1.igc.cat/web/es/sismologia_comact_anys.php

1204320 11/04/2012 21:17:14.70 41.58 N 2.60 E 4 2.9 Costa Maresme
l1204330 12/04/2012 04:46:39.60 41.58 N 2.59 E 8 2.1 Costa Maresme

Earthquake 6.8 and five minor replicas last night in state capital and beaches of Sonora.The first time I feel an earthquake,¡t was scary.

Yes, they are scary. That's why I always try to go outside asap!, it give me the creeps the creaking sounds from the structure and windows of the building, fortunately I did not felt nor hear any of the two new ones at the morning from Oaxaca, Mex. I live in a apartment building between an avenue full of cargo trucks and rail roads full of cargo trains and the building shakes every time either or pass by, and the sound is different or last longer, now that I think of it… I had never experienced a strong earthquake at the apartment, luck me :).

http://earthquake.usgs.gov/earthquakes/recenteqsww/Maps/10/265_15_eqs.php
MAP 5.3 2012/04/13 13:06:27 16.266 -98.039 14.3 OAXACA, MEXICO
MAP 5.4 2012/04/13 10:10:04 16.274 -98.112 10.1 OAXACA, MEXICO

 

[IronFloyd]

Here in Chile this is moving much more than we thought ... just occurred during a strong earthquake this morning (1:00 or so), supposedly of 6.7 or 6.3 degrees, and I'm also listening to a radio station where everyone is claiming that this was much stronger than those 6.3 degrees , and people do not understand why the authorities say one thing but the reality is that all we perceive VERY strong, in my case an old bottles fell off and broke, which had not happened with any other earthquake, except in F 27 earthquake in 2010, where I dropped everything ... the quake was very long, and soon after it off a friend called me at 2 am about to tell me he was listening to the hum famous (those who are listening on many parts of the world, right in front of where we live) .. in short, this is so strange and in this moment aftershocks continue to occur at much lower intensity... appear to have reported two deaths..


a few videos ... only makes up a while back:

http://www.youtube.com/watch?v=ihXdtfPfpzU
http://www.youtube.com/watch?v=R4EN5dV0dmA&feature=endscreen&NR=1

 

[Laura]

Curiously, our house seems to have moved though I didn't feel anything. A large crack has appeared in the wall in our office, tearing the wallpaper, and on the other side of the wall, in the bathroom, also tearing the wallpaper. Meanwhile, the level of our well has dropped significantly. Both happened on the same day.

 

[Laura]

Found this: http://earthquake.usgs.gov/learn/topics/groundwater.php

Groundwater Effects from Earthquakes

Note: Some of the explanations below are speculative and should not be relied upon for decision-making. Please see the reference articles (below) for published results.

Seismic waves have two main types of effects on groundwater levels: oscillations, and "permanent" offsets. Muddy or turbid water at long distances from the epicenter are most likely an aftereffect of oscillations.
{...}

A theory for the oscillations was developed by Cooper et al. and refined by Liu et al. This theory is based on the idea that seismic waves cause expansion and contraction of the aquifer tapped by the well, in turn causing oscillatory pore pressure changes. If the aquifer has high enough transmissivity, then these pressure changes cause flow into and out of the well. The flow in turn sets up resonant motion of the water column. For most well-aquifer systems, the theoretical dominant frequency is around 10-30 sec based on the height of the water column. Following this theory, the head changes in the aquifer induced by the seismic waves are actually only a fraction of the water-level changes in the well.{...}

The "offsets" are harder to explain. They have also been known for decades (eg., the 1964 Alaska quake papers). We do expect offsets in the "near field" of an earthquake because the fault offset produces permanent expansion and contraction of the surrounding rocks. At distances of 100's or 1000's of km, however, the permanent ground deformation is negligible.

Some observations about the steps:

* Certain wells exhibit the offsets; most do not.
* At wells that respond this way, the offsets are always in the same direction; that can be either up or down.
* In hot-water wells, the offsets are frequently rises.
* The largest offset recorded digitally is a 1-m rise caused by the 1989 Loma Prieta earthquake in the BV well at Parkfield (see Roeloffs, 1998).
* The offsets can be "instantaneous" (to the resolution of the water level sampling interval), or they can begin abruptly and take days to weeks to reach their maximun (or minimum) values. The slower responses generally follow curves that are well-matched by a 1-D groundwater diffusion model, ie., the shapes of these curves suggest that seismic waves change water level "instantaneously" at a location near, but not at, the well.
* The offsets are not limited to shallow depth. The deepest recorded one was probably the response of the Long Valley Exploratory well to the Oct 16, 1999 Hector Mine earthquake (about 400 km away). Fluid in the this well is in communication with a transmissive fracture at a depth of 2.6 km.
* For each well exhibiting offsets there is usually a magnitude-distance threshold that will predict whether or not an offset will be observed. For example, a M5 event 20 km away might produce a step; if the event is 400 km distant it would need to be a M7.

Some possible mechanisms for the steps

* For upward steps in shallow wells, compaction of overlying alluvium such as occurs during liquefaction is a possibility (Roeloffs, 1998)
* Escape of small amounts of exolved gas from pore space could cause fluid pressure drops (Matsumoto and Roeloffs)
* A change of permeability due to unclogging of a fracture by flow induced by seismic waves (Brodsky et al.)
* At Long Valley, incremental amounts of dome inflation triggered by seismic waves (Roeloffs et al.)
* In hot water wells at Long Valley, thermal pressurization due to upward movement of hot fluid triggered by seismic waves (Roeloffs et al., submitted).

Scientific importance of all this: From my viewpoint, the most important scientific implications have to do with the remote triggering of seismicity (and possibly volcanic eruptions) by large earthquakes. Seismic waves at distant locations are transient, yet they can trigger seismicity that persists for days (or longer) or larger events that are delayed. It is known that increasing fluid pressure can trigger earthquakes (lab and induced seismicity studies), and the seismic-wave-induced fluid pressure offsets are effects that last much longer than the duration of the seismic wave train. It also appears that triggered seismicity preferentially occurs in hydrothermal areas, and that in these areas fluid pressure rises are more likely to be increases. The exact mechanism linking the fluid pressure changes and triggered earthquakes isn't yet pinned down, but the circumstantial evidence for a connection is rather compelling.

{...}

Changes caused by permanent deformation (strain) only last until the pressure equilibrates with the water table. This can happen in minutes or may take months. The time scale is approximately given by the square of the aquifer depth divided by the vertical hydraulic diffusivity of the overlying material. This is only relevant in the near field of the earthquake. Other step-like changes tend to recover on the order of weeks or months. The mechanisms of most of these changes are unknown, so the mechanism of their recovery is unknown. The recovery may take place by flow to the boundaries of the hydrologic system, so the time scale is governed by the distance to the boundaries and the hydraulic diffusivity.

{...}

When an earthquake in Alaska changes water levels in the midwest US, for example, producing a "step-like" change, we don't really know the reason. So, we also don't know how the aquifer pressures are affected away from the wells, and we don't know the types of flow that would be set up by these effects.
References

Cooper, H. H. Jr,J. D. Bredehoeft, I.S. Papadopulos, R. R. Bennett, The response of well-aquifer systems to seismic waves, J. Geophys. Res., 70, 3915-3926, 1965.

Leggette, R.M., and G.H. Taylor, Earthquakes instrumentally recorded in artesian wells, Bulletin of the Seismological Society of America, 25, 169-175, 1935.

Liu, L.-B., E. Roeloffs, and X.-Y. Zheng, Seismically induced water level fluctuations in the Wali well, Beijing, China, Journal of Geophysical Research, 94 (B7), 9453-9462, 1989.

Matsumoto, N., Regression analysis for anomalous changes of ground water level due to earthquakes, Geophysical Research Letters, 19 (12), 1193-1196, 1992.

Matsumoto, N., and E. Roeloffs, Hydrologic response to earthquakes in the Haibara well, central Japan: II. Possible mechanism inferred from time-varying hydraulic properties, submitted to Geophys. J. Int., Sept. 2001.

Roeloffs, E., Persistent water level changes in a well near Parkfield, California, due to local and distant earthquakes, Jour. Geophys. Research., 103 (B1), 869-889, 1998.

Roeloffs, E., M.Sneed, D.L.Galloway, M.L. Sorey, C.D. Farrar, J.F. Howle, J.Hughes, Water Level Changes Induced by Local and Distant Earthquakes at Long Valley Caldera, California,submitted to Bull. Volc. Geotherm. Res., 2002.

Waller, R.M., H.E. Thomas, and R.C. Vorhis, Effects of the Good Friday earthquake on water supplies, Journal of the American Water Works Association, 57 (2), 123-131, 1965.

Woodcock, D., and E. Roeloffs, Seismically-induced water level oscillations in a fractured-rock aquifer well near Grants Pass, Oregon, Oregon Geology, 58 (2), 27-33, 1996
Acknowledgments

Thank you to Evelyn Roeloffs for providing the information for this webpage.

Another: http://www.grecksch.de/roermond.html

Analysis and interpretation of well level changes induced by the Roermond earthquake of April, 1992

This project has been supported by the Deutsche Forschungsgemeinschaft (DFG), completed June 1999

References
Grecksch, G. (1999): Analyse und Interpretation von Brunnenspiegelschwankungen als Folge des Roermond-Erdbebens vom April 1992. - PhD thesis, University of Bonn, 132 pp. (published by Shaker Verlag GmbH, 1999, ISBN 3-8265-6117-1)

Grecksch, G.; Roth, F. & Kümpel, H.-J. (1999): Coseismic well level changes due to the 1992 Roermond earthquake compared with static deformation of half-space solutions. - Geophys. J. Int., 138, 470-478

Project summary (summary of PhD thesis, extended by selected figures):
On April 13, 1992, a MW 5.4 earthquake occurred near the city of Roermond, the Netherlands, in a focal depth of about 17 km. This so-called 'Roermond earthquake' was the strongest event in Central Europe since 1756. Following this earthquake, the water levels of numerous wells located in the Lower Rhine Embayment showed significant coseismic anomalies. For the period of March to May 1992, we collected records of altogether 189 continuously operating well level sensors. After deselecting signals that were most likely triggered by instrumental effects, 59 data sets were kept that showed significant earthquake-induced dynamic or step-like responses of cm amplitude. Advances in understanding these phenomena may improve the knowledge of the role of pore fluids in crustal rheology, and are essential for the study of hydrologic earthquake precursors. They are also of some relevance for the assessment of risks of toxic waste disposals, and for matters related to the production of hydrocarbons. In order to explain the observations, two potential mechanisms were investigated: the poroelastic response of the well's vicinity to the static volume strain field of the earthquake and discrepancies in local pore pressure in the context of changes in hydraulic aquifer properties, released during the passage of seismic waves.

A coseismic strain imposed by an earthquake is expected to result in a step-like well level change. In a simple, linear model, water levels fall or rise depending on whether the connected aquifer expands or contracts in response to the seismogenic redistribution of the regional strain field.

{continues with graphs and such}

And: http://www.fujitaresearch.com/reports/earthquakes.html

Earthquake Prediction

{...}

2. Ground Water Levels

Changing water levels in deep wells is recognized by the IASPEI as a significant precursor to earthquakes. Perhaps part of the reason for this is explained by the discoveries of German scientists working at “KTB”, which is planned to be the deepest hole ever drilled in the earth’s crust (to 10 km). At a depth of 3 900 m the researchers struck water. A heavy brine with a salinity twice that of sea water, it was at a temperature of 118°C and contained 80% by volume of gases in solution, principally N2(70%) and CH4 (29%). The discovery of this brine led the researchers to postulate a “crustal ocean”, with tides, currents, and flows, all of which could conceivably react to seismic activity.

No simple model exists to connect pre- or co-seismic fluctuation of ground water levels to this crustal ocean. Lomnitz (3) considers that, ultimately, the mechanism will be found to be related to pressure changes, rather than changes in volume in the focal region (as most geophysicists currently believe). Such regional pressure changes, can be detected at deep wells.

The sensitivity of deep wells to seismic activity is remarkably varied. A number of deep wells in China are reported (4) to be extremely sensitive to changes in pressures, and can reliably detect earthquakes occurring halfway round the world. This observed sensitivity is probably due to their being quite protected from surface noise (rainfall, seasonal effects, etc.). As a result, China relies a great deal on deep wells for earthquake prediction. Indeed, over 100 research wells in excess of 1000 m deep have been drilled solely for earthquake prediction purposes. In these wells, water levels are continually monitored to ±0.5 cm and temperatures to ±0.01°C. Japan also relies to some extent on such wells - some 93 wells are monitored for earthquakes. In general a pre-seismic variations at observation wells follows this sequence:

1) A gradual lowering of water levels of a period of months or years
2) An accelerated lowering of water levels (rate often exponential) in the final few months or weeks preceding the earthquake.
3) A “rebound” where water levels begin to increase rapidly in the last few days or hours before the main shock. {...}

This: Water-Level Changes in Shallow Wells Before and After the 1999 Üzmit and DŸzce Earthquakes and Comparison with Long-Term Water-Level Observations
journals.tubitak.gov.tr/earth/issues/yer-05.../yer-14-3-3-0510-5.pdf

 

[mkrnhr]

Last night's earthquake (in Chile) was felt over more than 2000km. It was described as slow moving (low frequency waves) and lasted for more than 30 sec if I remember well.

I've been watching the interplanetary magnetic field measurements since the Sumatra earthquake and what i noticed is a certain correlation between rapid changes in the magnetic fields and the occurrence of new earthquakes (not the replica). It is possible that electric discharge phenomena do trigger both effects (sismic and magnetic) rather than being directly connected as cause and effect.

In the picture below, there is a calm magnetic activity to the left (before the Chilean earthquake), then more variations to the right (there have been a 6.8 earthquake in New Guinea a few hours later (7:14UT)). Not sure if it means anything really but it's worth watching IMHO.

 

[Bim]

Well, mother earth is really moving these days.

There was a 4.5 in Peru and a 4.8 in Japan today. There's been smaller shaking in the Caribbean sea, especially concentrated around Puerto Rico and the Mona Passage that separates them from us (Dominican Republic). My hope is that they remain small, but i'm also trying to stay alert just in case. I'm going to a public chat with an earthquake expert here tomorrow to get some answers and info.

 

[bngenoh]

This article brought this thread to mind:

A leading earthquake scientist has warned that the planet could be cracking up after a series of massive quakes in just 48 hours.

Expert Gheorghe Marmureanu - from Romania's National Institute of Earth Physics - says 39 quakes had hit the globe within two days.

The series started with two massive quakes in Indonesia measuring 8.6 and 8.2 on the Richter scale rapidly followed by three more only slightly smaller in Mexico within hours.

"There is no doubt that something is seriously wrong. There have been too many strong earthquakes," said Marmureanu.

He added: "The quakes are a surprise that cannot be easily explained by current scientific knowledge. With the Indonesian quake for example, statistically, there should be one big earthquake in this part of Asia every 500 years. However, since 2004, there were already three quakes with a magnitude of over 8, which is not normal.

 

[Yozilla]

Curiously, our house seems to have moved though I didn't feel anything. A large crack has appeared in the wall in our office, tearing the wallpaper, and on the other side of the wall, in the bathroom, also tearing the wallpaper. Meanwhile, the level of our well has dropped significantly. Both happened on the same day.

Hmm, wells are "drying up" and strong earthquakes (yet without casualties) all around the globe, sinkholes and strange sounds - Earth is growing according to C's and Sun's very threatening area of magnetic disturbances is rotating towards BBM... quite a upsetting prelude to even more dramatic events?

Well I've been pondering on possible behavior of tectonic plates in past few days: If I understand correctly "sub-ocean" plates are submerging under "continental" ones which are being lifted like it was the exact case for millenniums till nowadays .... So if our Big Blue Mamma is growing, existing quantity of crust will not be sufficient in future I guess ... What is bothering me is if than some tectonic plates in contact could start moving in opposite direction and should than upper "continental" plate start to lower down so some coastal areas could be sank?

If I remember correctly in some transcripts C's said that Japan(?) California(?) and Mexico will sink?

 

[Laura]

Update on our well: apparently, the level has NOT fallen, only the well was infiltrated by tree roots which began to fill it up and made it appear that the water level was down. Well-Man came and went down and cleaned it all out and said that our levels are better than other wells in the area, many of which HAVE fallen!

 

[MK Scarlett]

Update on our well: apparently, the level has NOT fallen, only the well was infiltrated by tree roots which began to fill it up and made it appear that the water level was down. Well-Man came and went down and cleaned it all out and said that our levels are better than other wells in the area, many of which HAVE fallen!

This is a pretty good news for you and the team at Castle Laura, because after have reading several articles in French about this matter I was worry about the level (very low) of water in your region... And you have a wells! Great news! I hope your infiltrations problems will be resolved soon. ;)