EARTHQUAKE HAZARD AND SEISMIC RISK (EGU-GIFT 2013-2017)
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francois.tilquin.38@gmail.com       

(by François TILQUIN highschool MARIE CURIE- ECHIROLLES- Academy of GRENOBLE - FRANCE)                  25/04/2017

thanks to Francesca CIFELLI Department of Science, ROMA TRE UNIVERSITY – ITALY francesca.cifelli@uniroma3.it )

and Jean Luc BERENGUER International High School VALBONNE – FRANCE berenguer@unice.fr )

How to use and build the SISMO BOX “do it yourself”, to discover hazard and seismic risk.

(Wait few seconds before navigate in this page, because it is big with a lot of pictures and videos. Thank you)

 

CONTENTS AND LOCAL LINKS

 

I) OVERVIEW VIDEOS   LINK TO ALL FILMS YOUTUBE INTEGRATED

 

Sismo box

Seismometer

Earthquake’s origin

Eathquake prediction

Resonance

Resonance at 3l/4

Ground liquefaction

Site effect excentric

Site effect Grenoble

Energy accumulation

Energy accumulation

Bearing wall

Roof amortissement

Shake table

Switch el. Screw-driver

Using excentric

 

 

 

 

 

 

Electronic shake table

Azimut software

 

 

 

 

 

 

 

II) RISK EQUATION and shown elements with SISMO BOX

 Source: UVED modified

Seismic hazard is defined by earthquakes causes (global geology), spatial and temporal occurrence, intensity. With the sismo box, man can show that it is possible to predict the location of an eathquake, but neither it’s intensity, nor it’s occurrence.

The risk depends of the hasard, and of the consequences on human lifes and activities. It is decreases by the resistance with paraseismic systems, and the resilience wich measure the capacity to limit it’s consequences.

It depends of the human comportments and public politicals.

 

III) THE SISMO BOX “DO IT YOURSELF”  


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Video BOX in hight definition

 

 

 

 


 

IV) ADDITIONAL EQUIPMENT TO MAKE A 1D-2D ELECTRONIC TABLE


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Video ELECTRONIC SHAKE TABLE in hight definition

 

 

   

 

Necessary equipment to make this experiment: (Conrad)

Dynavox mini-ampli Hi-Fi CSPA1 silver ref :76001 1 F7 39,90 €

2*High speakers SPEAKA HP 75-9 ref: 300237 1 F7 2*12,95 €

USB external sound card 7.1 USB2.0 ref: 87176 1 F7 39,95 €

 

The high speaker can be perforated to increase the movement amplitude, but the external sound-card is very efficient, particulary with laptop computers.

The main interest using a electronic shaking table, is to send to the table a real earthquake trace, and to approach the reality. In a real trace, all frequencies as present and the building resonance shows that phenomenon.

 


 

V) HOW AND WHY RECORDING EARTHQUAKES


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Video SISMOMETER in hight definition

How to build a sismometer:

Principle: record the relative movement of the earth compare with something immovable.

Ground vibrations are recorded by the relative movement of a magnet in a bobine (Induction)

The mass is considered as inmovable (inertia) and is hang with an elastic.

The movement of the mass after the earth vibration must be weakened by the slice wich is in the water.

Material: Tube, polystyren support, elastic, masse, magnet, pot with water, slices, bobine connected to Audacity, with external entry, and one channel.

Experiment: The polystyren must be stick on the earth support (table). Try the efficacity of the amortissement by lifting the mass then by dropping it.

Students can draw the system with 2 colors; one for what is moving in case of earthquake, and an other to draw what don’t move in case of earthquake.   

Important remarks: In all cases, you have to get maximum amplify. (on certain computers, amplification of sound-card is to low to see convincing things)

 

The bobine has approximately 100 tours, so the induction current is not so important. If you chock the table you can register something, but you have to amplify at maximum.


How to build yourself?

Polystyren can be cut with jig-saw or cutter and glue with a heater glue gun. Network thread recycling.

The inertia principle of Isaac Newton is used to undertand how a mass hung on a spring remains ephemerally immovable when the ground moves during an earthquake, and allows its recording.

 

Philosophiae Naturalis Principia Mathematica, 1686.

Isaac Newton (1642-1727)

AXIOMATA

SIVE

LEGES MOTUS

Lex I:

 

Corpus omne perseverare in statu suo quiescendi vel movendi uniformiter in directum, nisi quatenus a viribus impressis cogitur statum illum mutare.

 

Projectilia perseverant in motibus suis nisi quatenus a resistentia aeris retardantur & vi gravitatis impelluntur deorsum. Trochus, cujus partes cohaerendo perpetuo retrahunt sese a motibus rectilineis, non cessat rotari nisi quatenus ab aere retardatur. Majora autem Planetarum & Cometarum corpora motus suos & progressivos & circulars in spatiis minus resistentibus factos conservant diutius.

Latina text of Newton 1st movement law

 
http://www.preces-latinae.org/thesaurus/Introductio/Principia.html

http://www.loc.gov/exhibits/world/earth.html

 

Law I.

Every body perseveres in its state of rest, or of uniform motion in a right line, unless it is compelled to change that state by forces impressed thereon.

Projectiles continue in their motions, so far as they are not retarded by the resistance of the air, or impelled downwards by the force of gravity. A top, whose parts by their cohesion are continually drawn aside from rectilinear motions, does not cease its rotations, otherwise than it is retarded by the air. The greater bodies of the planets and comets, meeting with less resistance in freer spaces, persevere in their motions both progressive and circular for a much longer time. http://physics.info/newton-second/

 

VI) ORIGIN OF EARTHQUAKES:  


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Video EARTHQUAKE ORIGIN in hight definition

 

Principle: set an accumulation of energy with a lasagne until it breaks. A wave goes away from the rupture location and is recorded by the piezometer connect to Audacity.

Material: lasagnes, one or 2 channels on Audacity, one or two piezometers.

Experiment: Run audacity and break the lasagne: The disturbance goes around and stimulates the piezometer which records it. The earthquake appears around the fault: propagation: (risk exists even far from the earthquake). There is an amortissement with the distance.

 

 

 

 

We can see the amortissement with the distance, also that the signal is complex.

Delta t is 0.7 ms for the wave to go from one piezometer to the other. (0.8 m): 1.1/1.2  km/s in the polystyren. 

 

Important remark:

With certain laptop computers, the card sound does not allow the stereo acquisition. You have to get an external sound card ( Sweex: see below)

Connect the stereo piezometer to the front line in, and select in Audacity  “Line enter USB multi-channel” to active the USB external sound card.

parameters in audacity software


 

VII) MEASUREMENT OF THE SPEED OF THE EARTHQUAKE’ S WAVES:  

 

Principle: measurement of the earthquake speed propagation in different materials.

Material: 2 channels on Audacity, two piezometers, table in wood or concrete or polystyren piece.

The experiment is done with 2 pizometers and a chock with a hard piece of metal, or with a pencil (on the polystyren)

Measurement of different arrival times and distance between the 2 piezometers. (speed in concrete is ≈3.2 km/s) in polystyren (≈1.2 km/s)

 

Wave speed on the ground can be evaluate with Educarte software or Sismolog (see below).


 

VIII) DETERMINATION OF THE EARTHQAKE’S LOCATION AND WAVE SPEED:  

2 methods to locate near eathquakes: half plane (which can be experimental too in the classroom) et S-P circle, when we know speed, software Sismolog or Educarte.

Using Sismolog (Chrysis) author Julien FRECHET, François THOUVENOT (LGIT CNRS Grenoble) and the SISMALP seismic network: problem is we don’t know where was the earthquake, when took place the earthquake, et the speed of the wave. Once known the earthquake’s position by the half – plans method, we know all the rest.

Arrival time of P-wave

 

 

The first work is to determine the arrival time of the P-waves and S-waves.

Half plane earthquake location method

 

The method of the half-plans: we draw the mediator between 2 stations then we consider that the earthquake is in the half-plan of the station having received the wave P first.

 By taking stations 2 by 2 we determine a polygon in which is the earthquake.

 

The software draws a shadow in the half-plane which do not contains earthquake (not too visible here)

Once the position of the earthquake is known, we can calculate the wave speed and  t0.

This method can be used in clasroom (see below)

 

Circle S-P earthquake location method

 

 

The method of circles is possible when the speed of the P-wave and S-wave is known .

 

We have also to consider the depth of earthquake.

 

It seams the circles do not determine a precise point but a polygon when the earthquake is not superficial, but deep: There is a difference in the distance between the real route and the visible route of the waves.

 

 

P-Wave speed measurement on the ground with near earthquakes:

In this example, the earthquake depth is 6.51 Km. Each station has an altitude, a p-wave arrival time, a distance from epicenter which is calculate with GPS coordinates.

Légende encadrée 2: topography
 


 

To know the distance traveled by the wave, it is necessary to know the sum of 2 hypotenuses.

 

Sin α=depth/hyp1=height/hyp2 and Cos α=D1/hyp1=D2/hyp2

 

D1+D2=cos α(hyp1+hyp2) and Depth+height= Sin α(hyp1+hyp2)

 

Square and sum gives:

(D1+D2 )2+(depth+height)2=cos2 α(hp1+hyp2)2+sin2 α(hp1+hyp2)2

ans the wave travel is:

hyp1+hyp2=sqrt( (D1+D2 )2+(depth+height)2)

 

The array below shows that the error is not so big if we consider that the earthquake and station are at the zero level. 

Seismogram and p-wave arrival time

Earthquake depth is 6,51 km S

 
 

 

 

 

Station

Height (km)

Distance

D1+D2 (km)

Distance wave

Hyp1+hyp2

Arrival time (h:min:sec)

Delta d (km)

Delta t (s)

p-wave speed (km/s)

OG08

0,550

59,92

60,33

16:47:07.658

 

 

 

OG09 (-OG08)

0,630

34,86

35,58

16:47:03.345

24,75

4,313

5,73

OG13 (-OG08)

0,560

42,39

42,97

16:47:04.702

17,36

2,956

5,87

OG18

1,455

40,89

41,65

16:47:04.912

 

 

 

GDM (-OG18)

1,574

16,3

18,19

16:47:00.561

23,46

4,351

5,39

OG15

1,985

66,6

67

16:47:09.246

 

 

 

(OG15-) VAU

1,455

15,89

17,77

17:47:00.062

49,23

9,184

5,36

OG22 (-VAU)

1,810

91,85

92,23

16:47:13.303

74,92

13,241

5,65

 

We can observe some variations of the P-Wave and it is not really possible, at this level, to find a law.


Earthquake location in classroom, using microphones: a chock will be set: man do not know neither the location of the earthquake, nor the speed of the wave.

 

Material 5-10 double piezometers with long connectors (3-5 meters for a classroom, authorize the measurement of 6-10 meters)

One piezometer is very near of the chock (zero time) and the others are anywhere in the classroom.

The difference between the 2 arrivals is collected in an array.

The students have the map of the classroom and the differents piezometers are ploted on it.

Audacity must be with the maximum of point per second (96000 Hz) Edition, Preferences, Qualité.

 

Each group write on the blackboard the arrival time (difference beetween first spike and second spike)

On the individual map, students join station and draw mediator, then eliminate the half plane which does not contain the earthquake.

They can determine so, step by step, a polygon which contains the earthquake. (précision 30 cm in the classroom)

When earthquake location is determinate, it is also posible to have the wave speed.

Aclassroom map is written on the white board and arrival times to each station are red by the students and writtent on the white-board. The half-plane method allows the location of the eathquake with about 30 cm precision. The acquisition is made with a frequency of 100000 Hz. (The speed wave in concrete is about 3.2 Km/s)

 

How to build yourself?

You can command the 2 elements on the website http://www.conrad.fr

 

You have to separe the 2 mass connectors  which are rolled up together, and separe the 2 cords glued together. Weld the 2 mass of the connector to the mass of the 2 piezometers and make and weld the 2 active threads to the 2 active threads of the piezometer. Roll up the connection to strengthen.


 

Earthquake location in classroom using piezometers: without synchronisation.

No synchronisation between computers: we have only 5 mediators for 5 computers. Low precision in drawing the polygon wich contains earthquake.

 

 

With the top-synchro: 50 mediators with 5 computers. Signal synchro can be a small electric tension, with an artisanal multi-switch wich disconnect each computer after the top synchonisation.

 

Location far earthquakes: azimutal method Japan earthquake. Software AZIMUT©FT Free


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Video AZIMUT SOFTWARE:EPICENTER in hight definition

After running choose language, then right click, read selected position, directory japan, japan_azimut_virgin, place cursor near P-wave arrival, and Z to zoom, select the array of p-wave during about 20 seconds (click and slip), change eventually the amplitude of the signal in clicking in the selected array and look red arrow (in this example, amplitude 285 is good)  , then put the reading cursor at the beginning of the array selected (button home), click on the check corresponding to “tub” on the windows left of the station name, and run the trace: tube appears , drawing extremity of the main arrow.

Do this for the other stations ( red arrow in the station window to select the new station)

 

 

After drawing tubes, you have to place the azimut: in the gray windows left top, click on check Az and Paz: an orange circle appears on the select station: 3 proximal keys M, %, µ use with the mouse wheel to change Azimut, change size, change transparency.

The orange plane must split points in 2 equal parts.

Normaly the 3 azimut stations show the epicenter.

 


World location of earth quakes: Educarte (freeware) or Sismolog

Earthquake hazard, and if when populations leave near, we can speak about earthquake risk.

 

Educarte software (J.L. Berenguer, A.Lomax) World sismicity and cut defined to show Benioff plan.

 

 

 

Sismolog software (J.Frechet, F.Thouvenot LGIT Grenoble)

With Sismolog, we can change the width of the cut: earthquake are thrown on the middle line. The cut must be very perpandiculary to the Benioff plan, and it is then possible to measure the width of the lithospheric plate. 

 

IX) EARTHQUAKES PREDICTION ? WHERE, WHEN, HOW ?  


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Video EARTHQUAKE PREDICTION  in hight definition

Stick slip experiment with sismo-box “do it yourself” (sand paper, electric screewdriver with slow speed, elastic, rock block).

 


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Video EARTHQUAKE PREDICTION ? in hight definition

Stick slip experiment with step to step engine, sand paper, elastic, rock block).

 

 


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Video EARTHQUAKE PREDICTION ? in hight definition

Very simple device for the stick slip experiment.

 

Software  sets the good parameters of  audacity. If it does not run set the parameters of audacity to 1 channel, 1000 hz, 16 bits.  Experiment time: 30 second max. (because of the Excel number of point limits.

 

 At the end, export the wav file, (normaly Audacity make this in personnal documents etc…) just after, sismo-logic read this new file automatically and convert it in excel file, with formula, and run Excel.

Select the data from x until « Force » with shift and right-arrows and with «Ctrl» + «shift» + «down-arrow». Then go to the top with the lift and draw with “points cloud”

Treatement of Stick-slip experiment
 

 

 Change the slope and the shift of the blue line with a_droite and b_droite parameters to put it in the right position. Then it is possible to understand the difference between the theoretical and effective movement.

 (Possibility of using 2 channel to try to ask an user to hit on the second piezometer just before the slipping)

Possibility to draw with a pencil the positions, and to put it in excel.

Measurement the time between 2 slippings:

Try to correlate with the energy of the most recent slipping (energy is proportionnal to the square of the slipping trace= a sort of kinetic energy ½ m*v2). 

 

How to treat data to plot relation between slipping interval and energy.

By leaving of the intuitive hypothesis that more it has been a long time since an earthquake took place, more the released energy is strong, we are going to concern a graph the time separating two movements and the energy of the earthquake. If there is a correlation, we should see points getting organized according to a right.
The principle is to study the picture of the curve in staircase and to locate the moment when begins the step and the height of this one.
By placing the mouse without clicking the curve in staircase at the time of projections, appears the information allowing to find the values of time  in the picture and the value of the projection.

 

Using the automat with the excel sheet built by Sismo-logic

After sctick-slip wave file exportation, the software Sismo-lgic, ask to the user to verify the beginning of each earthquake (red line) and creates 2 new array: delay/ energy and time/energy. Correlation coefficient are calculated.

 

 

Results of the treatment energy-time separating two movements.
There is nothing really visible, although it seems to take shape a kind of cloud of points.
It seems to have a small correlation (0,208) between the time and the energy, because of the experimental protocole: the sand paper is more slippy at the beginning because we made a lot of small experiment for the development. (hypothesis) 

 
With Sismo-logic :

At the end of experiment, in Audacitymake File; Export or Export the selection.

After exportation, the sofware Sismo-Logic detects the presence of a new file .wav in tge directory fic_sismo_logic\ Audacity\ patin_tracte and print the traces with a red line before each beginning of sliping

It is necessary to verify that the software correctly worked, and you can move the red lines according to the menu above. Once after checking, click on OK to continue.

 

Datas ar automaticaly treated :

 A curve appears, containing the tracks of the sliding, the energy actually restored by the skate (curve in staircase), and the theoretical energy (just right above).

 

Interpretations of the curves of waste of the energy. (sismo-logic, Stick-slip results)

L’énergie libérée par le patin est représenté par la courbe en escalier (« Somme » des carrés de la trace).

The line represents the theoretical energy (trend curve of the curve in staircase, moved upward)

- We can characterize the time which separates two movements.

- The relations between the energy actually dissipated by the skate and the theoretical energy. Notion of delay in the balance.

- The relation between the magnitude and the delay in the balance.

 

 


Traitement of the datas with Excel : The access to the file is by the right click, then Seen the Excel file: it is necessary to make then only draw the curve by Excel.

The purple peaks (at the top) represent the "Square" of the track. The curve of the "Strength" is obtained by subtracting the energy dissipated in the average right. We so obtain the accumulation of energy and its liberation according to time. We also notice that the sliding is not proportional in the present strength before.

  

 

Treatement of data energy-delay between two slippings.

The right click in the previous curve allows to reach the correlations:

 

 

- We can, by using the box, characterize the correlation between the delay separating two earthquakes and the intensity of the second:

The Sismo-logic software calculated the coefficient of correlation  " loose Energy ", " delay  between 2 earthquakes ". In this example the coefficient of correlation is 0 .016.

 

- We can finally discuss the intuitive hypothesis that: " more it has been a long delay between two earthquakes more the energy of the second is strong?

 

- The geologists speak about period of return to indicate the recurrence of certain earthquakes. We can calculate Under Excel, average of the time of occurrence of the sliding of the skate.

 

- We can also calculate the standard deviation which measures the dispersal and which can express itself in % :

the formula is =ecartypep (first line ; last line). The add p in the formula means that it is a small number of values.

NB : The field of lines is seized in the mouse by one to click to slide after the seizure of the opening parenthesis.

 

- By redoing the experience(experiment) several times and the calculations, we can discuss the notion of fluctuation in the sampling. see the file

 

- Try of seismic prediction.

 

- 2 piézometer are necessary: the left one is going to record the sliping of the skate and the right one the moment when you estimate to be just before this sliping, by typing briefly above.

- In sismo-logic, chose Audacity for stick slip prediction (Line in USB multichannel, 2 channels, 22050 Hz).

 

- Make the experiment Proceed to the experience opposite; the experimentatorr presses on his piezometer as soon as he believes that the skate is going to move.See

 

- The mode of mathematical treatment of these data is not immediate, because if the experimentator always types as the earthquake took place, we shall have a strong correlation.

 

Conclusions:
We can also make vary the roughness, the mass, the steepness of the spring and show so that the more the friction is important, the more the accumulated energy is important, and that more the ground is elastic more the delay in the balance is important.
In every case, we can show that no sliding is predictable, good that we can determine an average frequency.

We could think that numerous small earthquakes allow the catching up, but curves show us that it is not really the case.
We do not see either forerunners of big earthquakes.
http://www.ac-grenoble.fr/webcurie/sismo/web_patin


 

X) CONSEQUENCES OF EARTHQUAKES WITH SHAKING TABLES:  


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Video RESONANCE OF BUILDINGS in hight definition

 


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Video E SHAKE TABLE2 in hight definition

 

Teaching goals

They are experiments of micro-earthquakes, carried out on models of buildings and intended to show the risks related to the seismic zones and the nature of the prevention of these risks in the paraseismic construction.

The various causes of the damage of the seisms can be shown on these functional models, such as the setting in resonance of the buildings, bad construction, and the ground’s liquefaction.

The solutions to adopt to solve each problem are also modelled by paraseismic constructions on the models: chaining, shape protection, floating foundations, important mass on the top of the buildings.

Many physical problems appear in this modeling: resonance, inertia, reduction in scale, blades vibrating, acceleration, potential energy, speed of a wave, signal decrease and of course, many problems related on earth sciences and particulary to seismology.

 

Using electric screw driver


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Video SWITCH E SCREW-DRIVER in hight definition

Experimental system:

The electric screw-driver is set on a support wich is fixed on the table with scotch.

The fréquency is variable by rotating the screw on the clamp collar.

 

Using excentric


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Video USING EXCENTRIC in hight definition

 


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Video BUILDING RESONANCE with EXCENTRIC in hight definition

The angle of the eccentric can be change to limit the vibration amplitude wich is obtained by moving closer or by taking away the arm of the screwing machine.The system of moving the arm along the eccentric must be fixed to be sure that the amplitude of the vibration is the same from one experiment to an other one (to invent)

The screwing machine is started by raising slightly the battery, and stopped by releasing it.

The vibrating plate must be in the best position before fixing it.


Resonance and building’s size, site effect.

 

 

(Mexico earthquake: same dammage in Mexico than at the epicenter: site effect)

volcan réunion

http://www.palais-decouverte.fr/expos/vst_2k7/vs_2k7/pages/page_s6_seisme.html

To understand picture as this, where the small buildings (5 stairs)  collapsed and not the big (15 stairs), it is necessary to study the resonance.

 

What frequencies present in a earthquake?

The sofware Simul_seismes©FT freeware makes the Fourier transforma of an earthquake traces:

You can acceed to this sofware from  .

Open the file 95090804.ASC (08 september 95 near Grenoble)  right click /Fourier Total

On the right Fourier transform of all stations (abscissa: amplitude, ordina: fréquencies). On the center the selected station.

This Fourier transformation shows that more far from the epicenter we are, more the hight frequency desappears and the low frequencies are present (as the trumpeting of the elephant wich can be eared very far away because of it’s very low frequencies)

We can see also that for certains stations, certains frequencies are amplified.

The conclusion is that for certain earthquakes, it is possible to see an amplification of certain frequencies (site effect or other phenomenons ?)


Testing resonance on shaking table:

Higth frequencies make resonate small buildings and low frequencies make resonate hight buildings.

This phenomenon is not proportional. It depends of the wave speed in the building.

 

 

With the screwing machine, change the fréquency and obsere the amplitude of each building. The amplitde of the stimulation must not be to big (buildings collapse when fundations are not resistant enough).

 

2 vibrating modes are seen:

 

Resonance at 3 l/4


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Video 3 LAMDA PER 4 in hight definition

 (Photos were made in low light without flash with a tripod)

The second mode is observed on the big building and the height frequency

The foresters say that in case of storm, trees break in 1/3 of their height. (in the position of the antinode)
A little of theory

à For the vibrating blades of length L with a free extremity, the blade being fixed at the other end, the modes of vibrations of the blade in the resonance ( maximal amplitude) are such as:

-         There is a body of vibration at the end of the blade

 

-         L = ( 2 k + 1) l/4   

      in using the relation l = V T = V / N we deduct that:

first mode : k = 0 , L = l / 4 , N = V / 4 L,

                         We observe a node and a body on the length L                                      

 

second mode : k = 1 , L = 3 l / 4 , N = 3 V / 4,

 we observe : a node, a body, a node, a body on the length L.

V=speed; N number of nodes;  l is the wave length; k=is an integer which is the range of the vibration.

 

à If the extremity is fixed (rope) then L = k l / 2  then N = k V / 2 L

We will reuse it for the site effect.

 

Evaluate the acceleration of buildings at differents stairs: with a small amplitude.

 

 

The simple accelerometers:

They are constituted by parallelepipeds in Plexiglas of the same section but of different height which we put at different heights on buildings and which allow to estimate the acceleration according to the height of the building and its possible echo. The more the height of the accelerometer is big, the more a low acceleration brings down it.

The scale of Mercalli indicates the awakening of certain persons in the superior floors.

l length of the basis ; h=height ; a=acceleration

 

If you put a mass upon a resonating building, vibration is amorted, and changes for low frequency. You can retrieve the new resonating frequence by decreasing the frequency.

 

Ground resonance with shaking table (site effect)


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Video SITE EFFECT EXCENTRIC in hight definition

We place buildings on a flexible support medium feigning alluvions and having it’s own resonating frequency; then by changing frequency of vibration, we succeed in making resound the ground and to amplify very strongly the amplitude of the initial movement.

We apply an horizontal vibration, and we can consider each column of alluvion as a blade.

By reducing the height of the alluvions, we increase resonance frequency.

 

 

Example of site effect (alluvion Grenoble basin)

The reality (Pierre-Yves Bard ingenior and researcher Grenoble) shows that amplitude of the movement is multiplied by 10-20 if we compare with the amplitude on the rock. If the thickness is important, frequency is low. The right picture had been done from the noise seismic bottom. Low frequency are amplified when the thickness of alluvions is important. (red color)

 


The site effect had been studied thanks to an analogic maquette in resin polyester filled with agar gely. Little pieces of fish food are put into gelly to see the movement. Films are done with 2 differents frequencies, and the pictures of extreme movements are extract from the video and colored in green and red. (DEWEZ Ambre DUMONT Isabelle SERRES Olivia (2010) students in Lycée Marie Reynoard near Grenoble)

 


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Video CENTER BASIN RESONANCE in hight definition

Using a 3D model resin polyester of Grenoble valley. Center of the valley resonates, with low frequency.

 


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Video EDGE BASIN RESONANCE in hight definition

Edge of valley resonates with hight frequencies vibrations.

 

 


Resonance of vibrating blades:

Fourier transform of the sound produced by a rule and recorded with a microphone, or a piezometer.

The software Audacity can draw the spectrum of the signal. We have to get the fundamental frequence (frequence for maximum amplitude). The rule must be very well fixed on the table.

The law is not proportional, but it is difficult to have the real law, because of the incertitude on the ruler length. However it is simple to show that the frequency of the resonance is not proportional with the length of blade.


How to build shake table, buildings and supports for them by yourself?

Reference of this electric screw-driver at the end of this document.


 

2 pieces of wood allow to sink not too much into the polystyren

 

 


How to build shake table, buildings and supports for them by yourself?

 

Buildings are done with the cover of exercice book, thin polystyren, a guillotine, needles and hot glue.

 

 

 


 

 

How to build an electronic 1D-2D shaking table?

 

   

 

Necessary equipment to make this experiment: (Conrad)

Dynavox mini-ampli Hi-Fi CSPA1 silver ref :76001 1 F7 39,90 €

2*High speakers SPEAKA HP 75-9 ref: 300237 1 F7 2*12,95 €

USB external sound card 7.1 USB2.0 ref: 87176 1 F7 39,95 €

 

The high speaker can be perforated to increase the movement amplitude, but the external sound-card is very efficient, particulary with laptop computers.

The main interest using a electronic shaking table, is to send to the table a real earthquake trace, and to approach the reality. In a real trace, all frequencies as present and the building resonance shows that phenomenon.

This system allows also to send relative high frequencies usefull to study building resonance in 3λ/4 mode.


 

Using the electronic shaking table with audacity:

 

- You need a real earthquake traces (3D eventually) to use this system, with a near earthquake.

- After you have to convert this trace in .wav file to use Audacity.

 

Getting a 3D .wav trace of an earthquake:

With sismo-logic run the item “Audacity for shake table 1D-2D” and good files will be loaded in Audacity.

 

Making a 3D .wav trace of an earthquake

- Connect to http://www.edusismo.org then flag English, Seismic data, Seismogramms selected, Choose fom the list, 2010, Confirm, 08/07/2010 SSE MANOSQUE (04), click on the eye.

 

- Then choose NICF station, and downlad the 3 components Z.SAC, N.SAC, E.SAC (vertical, north, east)

 

- You have now to convert .SAC file in .WAV file for audacity with Seisgram2K software.

Download Seisgram2K on http://www.edusismo.org , “Educational Resources”, “Acess to media ressource”.

In seisgram2K menu Fichier, Selectionner Fichier…, multiselect your 3 files with Shift-click ,Button Ouvrir.

 

The 3 traces appear in Seisgram.

Then take menu « Fichier », « Enregistrer actif sous », Wave file in « Fichier du type », and choose a directory and a name. Seisgram add “Composante0, composante1, composante2, format Wav and PC_INTEL button « Enregistrer ». Seisgram ask for the multiplicator frequency: choose 1 for the initial frequency or 2, 3, 4 to increase the speed. It is sometimes necessary to increase frequency because certain sound cards do not know how to sort infra- sound waves. (<20 Hz)

You have now 3 Wav files wich can be run with Audacity.

 

Using WAV file with audacity,

 External sound card Sweex wich must be connected to the computer, before running Audacity and connected to the amplifier in front 2.1 (facultative using),

Amplifier dynavox with amplifier button max, bass button max, and heigh-speakers connected back.

 

In Audacity, menu “Fichier”, “Importer” and multiselect with shift click, manosque_composante1 and 2:

Click on the left arrow of each trace and put the first trace in “Canal gauche” (left channel) and the second trace in “Canal droit” (right one)

If you have the external sound card, select it.

Select the maximum amplitude for Audacity output, and verify that the computer sound is on et is maximum.

 

Put the cursor just before earthquake, and read the sound with the classical green button.

You can simulate differents magnitude, in changing the amplification with Windows, Audacity, or the Dynavox amplifier button. 

 

Ground liquefaction and fundations.


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Video GROUND LIQUEFACTION in hight definition

Buildings are built well, but the heterogeneousness of the foundations causes their collapsing.

 

The results are better when the foundations are reduced to segments as it is often the case in reality.

It is necessary to put some sand and to moisten it. We observe that the water rises and that the building collapses if the basement is heterogeneous.

The objective of the engineers will be to verify the homogeneity of the basement.

 

XI) TESTING EATHQUAKE RESISTANCE SYSTEMS   

When the hazard is known the risk depends on the building fragility. The earthquake-resistance of the buildings decreases the risk.

 

 Bearing walls


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Video MODE OF CONSTRUCTION in hight definition

 

Bearing walls must fom top to botom of the building and be perpandiculary.


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Video MURS PORTEURS in hight definition

The goal for these students is to make buildings with wall and staires and with only 4 pins by stair. If bearing walls are parallel the building does not stand, and after several tries it is necessary to strengthen it.

They can test their buildings on shaking tables.


Rolling fundations:


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Video ROLLING FONDATIONS in hight definition

The principle is to isolate the building from the ground.

 

 

The movements of the ground are weakened, and it is particulary visible on height frequencies, but we can see an amplification on low frequencies (resonating of the weakened system), wich is not the searched effect.

 

 

Denis DAVI CETE Méditerranée (p75)

 

It is easily demonstrable (by the experiment), that this system can be likened to an inverted heavy pendulum and that the frequency of resonance can find itself by the classic formula.

The main difficulty is to make the lower half-sphere

Source: http://www.cotita.fr/IMG/pdf/JT_seisme_2012_J2_2_Conception_parasismique_ponts_1_Analyses_V3.pdf


 

Triangulated contreventement


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Video BEARING_WALL_BAD in hight definition

The construction is not good and has to be reinforces with triangulated system.

 


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Video TRIANGULATED_SYSTEM2 in hight definition

Triangle is not deformable

The model of building must be built with a single pin by floor and the parallel bearing walls. We can add a lead small piece above to favor the instability. Without contreventement, the building collapses when it is submitted to an earthquake. After strengthening, the building remains standing.

 

Top amortissement system.


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Video ROOF AMORTISSOR in hight definition

87th Floor Taipei tower

From Wikipedia, the free encyclopedia

Movement absorber

 

Leaky plate of Manilla paper is pearced with two nails. A wire, in which a lead of 75 g passes, is tightened between the two nails. An elastic returns the lead in its equilibrium position.

 

The set is fixed at the top of the building.

 

When the building moves, the lead tends to remain immovable. The elastic stretches and returns the building in its initial position, what limits its movement.

 

 

 

We search the resonance frequency when the mass is fixed, then we release the mass and we see the amplitude of the movement which decreases.

The mass size has probably an influence, and the steepness of the elastic too. Results seems to be better with a small mass and a very lung elastic. Those parameters can be tested.

How to build movement absorber by yourself?

 

 

 

The resonance frequence of the building must be probably very different than the frequnce of the movement absorber. We have not tested enough this movement absorber to be able to define it’s best characteristics.


 

XII) MOVEMENTS OF THE 2 SIDES OF A FAULT with Azimut software:  

Example of Japan: read all earthquakes of japan, and click on the first check general Gn to have the main arrow. What king of movement in Europe? Japan goes on the pacific, an we have gone at the opposite direction why ? Fault in japan and opposite movements in France.

Earth rotondity and slope of the fault make that Europa felt first the pacific movement and not the Japan movement. So we have the proof than the movements on both sides of the fault are opposite.

Superficial Japan earthquake: first movement of France was up.

Deep Earthquake in Okohtsk sea: same fault  movement, but deeper and closer from France. The first movement of France was down.

 

 

Energy accumulation:


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Video ENERGY ACCUMULATION in hight definition

Simulation of the 2 opposite movements from one side to the other of a fault, with 2 blocks, 2 elastics and the electric screw-driver. The movement is regular, and forces accumulate, until the slipping.

 


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Video ENERGY ACCUMULATION in hight definition

The step to step engine pull regulary on the right spring, and energy accumulates in the 2 springs, until slipping. The 2 blocks slip in the opposite direction.

 

Sofware “Mecanismes au foyer” modelizes this phenomenon and explains the ambiguity of the representation mode of faults mechanism.


 

XIII) AZIMUT© FT 12/2011 FREE SOFTWARE  

 

Goals: The software shows the 3D ground movments from the 3 components earthquake stations. The software shows ground speed vector, P, S and L waves, and the vector extremity with small balls. Epicenter can be found also with tools wich uses the vector extremity and the user decides the best direction.

 Why do japan earthquake pushed us, althow japan went on the pacific ocean for few meters?

Samoa eathquake pull us: why?

This software is also able to record movements of USB accelerometer and is able to drive 1-3 Cassy interface(s) for a shake table.

First ground movement: temporary depression  (Samoa)

Perpendicularity of P-wave and S-wave. 1st arc pointed.

 

Azimut and ground compression

 movement : Japon (1st arc)

Perpendicularity of P-S waves

(Vector extremity during few sec)

Love wave :S-wave horizontal and  perpendiculary to azimut.

 

Epicenter determination with 3 azimuts of P-wave during 10 s.

Ellipticity of Rayleigh wave (P-wave perpendic with surface and azimutal)

Acquisition of trace from a USB accelerometer.

 


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Video AZIMUT SOFTWARE:EPICENTER in hight definition

 

Using Azimut software and “Sismos à l’Ecole” sensor with a small jump in the school.

 

 

 

 

During this last essay, we find well 3 phases of the jump: the takie-off preparation which is translated by a movement downward, then the take-off which is translated by a movement upward and the more or less synchronous exaggerated landing with a sort of kick-ground which is well translated by a movement downward, with return in the oscillating balance.

 

“Taking off” preparation

(downward ground movement)

“Taking off” (upward ground movement)

“Landing” (downward ground movement)

Decomposition of three phases of the jump of the students


Download software Azimut (512 Mo)

 

XIV) DIFFERENT PEDAGOGICAL SHAKING TABLES :  

Simple study of BUILDING’S resonance and earthquake resistance in the classroom.


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Video 1D SHAKE TABLE in hight definition

The first one D pedagogical shake table (nov 2005 CERN Geneva). Real earthquake is send to Leybold interface by a dedicate software (simul_seismes FT). The a controlled sinusoïd is sent to the vibrator. Resonance, Amortissor, ground liquefaction can be shown with this experimental devices.

 


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Video 3D SHAKE TABLE in hight definition

The 3D shake table consist in 3 loud speakers connected with 3 numerical- analogical Leybold interfaces, connected to the computer. The signal is a real 3D earthquake vibrations sent to the interface by the Azimut free-software.

 


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Video STRONG EARTHQUAKE in hight definition

The building is a spring and we can see the lateral scissoring and the waves climbing in it from the ground.

 


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Video ROLLING FONDATIONS in hight definition

Very basic shaking table with an electric screw-driver, an excentric, and a clamp collar to hing the speed button.

 

These experiments simulate seismic vibrations on very simple plastic buildings, more or less good built, with or without bearing walls or fundations, chaining or not, put on rolling fundations.

It is possible to study resonance of differents various height buildings, resonance of the ground as alluvions valley, in using differents vibrations systems and a lot of other problems.

 

 

 

 

 

The lower cost shake table (from 0 € to 12 €): only sinusoïdes vibrations

 

The shake table built with an old stereo equipment (sinusoïdes and earthquakes vibrations).

 

The first peagogical shake table presented at Science on stage nov. 2005 (sinusoïdes and earthquakes)

The 3D pedagogical shake table

(sinusoïdes and earthquakes)

Shake table built with simple electronic equipement (sinusoïdes and earthquakes) (110 €)

 

 

 

 

 

Download softwares and applications :http://www.ac-grenoble.fr/webcurie/sismo/web_patin

 

THANKS TO  

Scientists: Pierre-Yves BARD (Searcher IFSTTAR), Michel CARA (CNRS BCSF Strasbourg), Françoise COURBOULEX (CNRS UMR Geoazur, Valbonne), Francesca CIFELLI (Dipartimento di Scienze Geologiche, Roma Tre), Filippo CAMERLENGHI & Lucas MARIANI (Video), Fabrice FINOTTI (Les Films Associés), François THOUVENOT (CNRS LGIT Grenoble).

 

 

Important remarks:

If some people see errors or critics, send them to me: francois.tilquin.38@gmail.com

Say too if you have difficulty to use the Sismo-box “do it yourself”. Thanks.


 

XV) COST TO BUILD THE SISMO BOX “DO IT YOURSELF” IN €   

Réf : 952463 Castorama;

2*( Polystyrènes extrudé BD 1,25m x 0,60 m ép.20mm ; Unit 1,88 €)

 

(for all supports: shake table, liquefaction, seismometer…)

3,76

Réf. : VMP0111 VPC display

Plaque Polypro blanc

¼ *( Alvéolé 80 cm*120 cm ep :3mm Unit 2.03€)

Plaque Polypro blanc 450gr/m² - Epaisseur 3mm (basement of shake table, hanging walls of building to build)

0,5

Réf: 456988 http://www.rougier-ple.fr

1/12*( Carton mousse-plumes 50x65cm ep :5mm Lot de 4 :17,5€)

Carton plume 5mm classique lot de 4(stairs of all the buildings)

1,5

1*( Cahier classeur Casino

2 .95 €)

(wall of built building)

2,95

1/19 *(Epingles patafix élastique 1 Buro+ 28,5 20,85 €)

      

(to build buildings and fix stairs at walls)

2

Réf : 488105 Castorama

1* (Perceuse sans fil 12 V HP12CD.

12,9 €)

(electric screw driver: shake-table and stick-slip)

12,9

Réf : 592896 Castorama

0,5*( 2 colliers de serrage inox L8 x ø 32 – 52 Unit :3,69 €)

 

  (to change rotation speed)

1,84

Réf : 811345 ; Castorama

¼ (Tube IRL tulipé gris. Ø : 16 mm. Long: 2 m. Unit 0,9 €)

 (rollers of the movment absorber)

0,2

Réf : 811347 ; Castorama

½ (Tube IRL tulipé gris. Ø : 20 mm. Longueur : 2 m Unit 1,1 €)

 

 (for the box-transport and high-speakers)

0,6

1/19 *(Tourillon Hêtre 1.5 €, 0,8 cm et 0,9 cm Tourillon sapin 10.5 €)

(for shake table)

1,5

Réf : 123401 Castorama 22/20 * (Vis plaque de plâtre 3,5*25 1,5€ les 20)

3,5x25mm (for the e- shake table support)

1,5

Réf : 123509 Castorama  2 /20 * (3,5x55 2,7€ les 20)

3,5x55mm (for the seismometer support)

0,27

Réf : 634175 Castorama 1/10 *(Tire-fond acier zingué 2,45€)

5 x 50mm  (for the seismometer)

0,24

Réf : 110562 Castorama 1/10*(10 Boulons tête fraisée acier zingué 4 x 50 mm 2,45€)

 (for the seismometer)

0,24

Réf : 110442 Castorama 1/10*(10 Écrou hexagonal acier zingué Ø 4 mm 1,5€) 

(for the seismometer)

0,15


 

Réf :  634310 Castorama 1/100 (100 Pointes tête plate 3.4 x 80 mm unit 2,6 €)

 for stick-slip (medium speed)

0,03

Réf : 634277 Castorama 1/100*(100 Pointes tête plate 2.2 x 40 mm unit :2,6€)

 for stick-slip (low speed)

0,026

Réf : 634271 Castorama 2/100 Pointes tête plate 1.4 x 25 mm unit : 2,6 €)

 to hold the connector on the high speakers

0,052

Réf :4595 16/50*( Cheville - lot de 50 - vert - 7x35 mm Unit. 3,75 €)

 

Cheville - lot de 50 - vert - 7x35 mm -  - cheville-divers (to assemble support in polystyren)

1,2

Réf : 579076 Castorama

0,5* (Lot de 2 bandes 100 x 610 mm – assortim. MAC ALLISTER. Unit 9,9 €)

(for the stick-slip experiment)

4,45

Réf : 552384 Castorama

1*( Boîte de rangement Kliker violet 35L. L:57 x l:39 x h:20,5 cm.

Capacité : 35L.unit 10,9€)

10,9

Réf : 224450 ; Décathlon

2/3*( Plomb olive bombée percée 75g CAPERLAN Unit 2,29 €)

 

(mass for the seismometer)

1,52

Réf: 618068; Décathlon

1/8 *(Zim fluo elastic Unit 2,75 €)

 

(elastic for the seismometer)

0,35

Réf : 264156 Castorama

1/19 *(2 *Colle transparente sachet 1kg Bâtons de colle à chaud. Unit 12,8 €)

 

(to stick polystyren and everything)

1,34

Réf: 1605262 ; Décathlon

1/10* (Boite assortie gaine Unit 4,95€)

 

(to fix elastiq on the roof movement absorber)

0,5

Elastiq, règle, scotch Casino 1,5

 (for the stick slip experiment and to fix bobine on support)

1,5

Réf :543470 : Casto L.62,5  h.25 Ep 5cm.

Siporex Concrete

(2/16)*1,25€

 (for stck-slip experiment)

0,15

Ref : 150401 ¼* (Sandow 10m 6 mm Castorama 8,35 €)

 (to study the rope resonance)

2,08

Réf : 588263 Conrad

1/19*(  FER A SOUDER 20 / 120W 2

10,95)

(Tin solder)

0,52

Réf : 120369 Castorama Crochet à vis laiton Ø 2,5 x 10 mm. Lot de 10

1/10 *(2,4)

Réf 560236 2*(Equerre acier 80 mm 0,85€)

Crochet à vis laiton Ø 2,5 x 10 mm(for the seismometer)Equerre de chaise acier zingué 80 mm Vynex(to fix the e shake table support)

2

Ref : 710318  Conrad

2 *( Cordons Jack 3.5 Mm Stereo Droit K3,5S/1,20 Unit 1,6 €)

 

 

(piezometer connector)

3,2

Réf 710397 Conrad

2 *(Transducteurs Céramique Piézo Epz-27Ms44W 190051 unit 0,63 €)

 

 (piezometer=simple seismometer)

1,24

Réf : 154296 Castorama

1/19 *( Rondelle plate large inox A4. Dimensions : Ø 6 mm. En sécurisac de 28 pièces. 5,62 €)

 (to rotate the clamp collar of the screwer)

0,3

Réf : 155929 Castorama

¾ (Sangle d'arrimage polypropylène avec came à griffes 5 m unit 3,26€)

(to close and carry the sismo-box)

3

Réf : 609755 Castorama

1/10*( Colle époxy rapide SADER. Unit 8€)

 

 (to stick the slice on the clamp collar)

0,8

Réf : 185106 Conrad

2* Petit aimant-puissant-permanent-PIC-M0805 unité :1,35 €

 (to make induction in the bobine of the seismometer)

2,7

Réf : 242536 Conrad

1*(Fil de cuivre peint 0,15 mm incolore Mayerhofer Modellbau)

 (to make the induction current of the seismometer)

4,8

(Earthquake’s location in classroom

Réf: 731471 Conrad :10* (Jack 3,5 mm 2 p. unit:0,45€)

Réf: 731498 Conrad :10* (Jack 3,5 mm 2 p. unit: 0,45€)

Réf: 604934 Conrad: 17/50 *(wire 50m 0.75mm unit 18,95€)

 

(to simulate an earthquake in the classroom and locate it with 5 stations)

(15,5)

 

Sum

70 €

 

Additional equipement for the electronic shaking table and experiments with laptop computer

 

f: 87176; 1*(Conrad  USB 2.0 external sound card Sweex. Stereo acquisition for wave speed and good amplification of low frequencies etc…)

 (to replace the sound card of the laptop)

39,95

Réf : 062563-62 ou 76001 ; 1*(Conrad

Dynavox mini-amplifier Hi-Fi CSPA1 silver )

 

(to amplify output signal of the sound card to the high-speakers of the e- shake table)

39,90

ou

49,95

Réf: 300237; Conrad

2*(High speakers SPEAKA HP 75/90 à unit:12,95 €)

 (to make the movement of real earthquakes to the

e-shake table)

25,9

Réf : 325090 ; Conrad

1*(Connexion RCA / jack, 2 m 4,7 €

to connect sound-card to the amplifier)

(to connect sound card to the amplifier)

4,7

 

Sum

110,60 €

or 120 €

 

XVI DOWNLOAD SOFTWARE   
 (automaticly unzipped in \sismobox and run with \sismobox\sismo-logic.exe )
you can copy the \sismobox folder on a usb-key and run with \sismobox\sismo-logic.exe

1_sismo-logic_ULTRA-LIGHT : basic software with Audacity portable, which set Audacity for parameters for differents experiments, and treats data of stick slip experiment.

1_sismo-logic_ULTRA-LIGHT.zip (98 Mo)

2-sismo-logic_ULTRA_LIGHT_doc : doc and powerpoints documents wich explains differents functionality and how to build sismobox « do it yourself »

2-sismo-logic_ULTRA_LIGHT_doc.zip (219 Mo)

3_sismo-logic_software_azimut :AZIMUT software wich treats 3D components.

3_sismo-logic_software_azimut.zip (512 Mo)

4_sismo-logic_dossiers_films : differents films and software to use with the sismobox

4_sismo-logic_dossiers_films.zip (408 Mo)

5_sismo-logic_softwares_edusismo : 2 free softwares of Edusismo.org site.

5_sismo-logic_softwares_edusismo.zip (593 Mo)