SALVADORI'S GUIDE TO TALKING WITH YOUR STUDENTS

Transcription

1 SALVADORI'S GUIDE TO TALKING WITH YOUR STUDENTS TSUNAMIS

2 SALVADORI'S GUIDE TO TALKING WITH YOUR STUDENTS TSUNAMIS Intrductin...1 Exercise 1: The Frce f Water...3 Exercise 2: Ripple Effect... 5 Exercise 3: Tsunami in a Bttle...7 Exercise 4: Water in a Bag...9 Questins t Ask Yur Students...12 Vcabulary...13 Resurces

3 Salvadri s Guide t Talking with Yur Students Part 2: Salvadri s Guide t Talking with Yur Students is intended t help yu have a cnversatin with yur students abut natural disasters with regards t the built envirnment. These hands-n exercises can help students understand the phenmenn. We have als included a vcabulary list and a list f resurces fr further explratin and tsunami safety. Nte: all bld/red wrds are defined in the vcabulary sectin. What tsunami means: The wrd tsunami cmes frm the Japanese wrds tsu meaning seashre village and nami, meaning wave. are giant sea waves that impact seashres. Why a tsunami frms: ccur when the level f the sea flr drps suddenly, usually alng a tectnic bundary. Earthquakes, landslides, r vlcanic eruptins can cause the sea flr t drp. As the sea flr drps, the sea purs int the vid; the resulting frce f the mving water causes waves. The resulting waves have perids (the time that passes frm ne wave crest t the next) that range frm five minutes t ver sixty minutes. In the pen sea, the wave height may start at a meter r less, but as the wave appraches the shreline, its height grws as the distance between the sea flr and the water surface decreases. This happens because the bttm f the wave is slwed dwn by frictin against the grund while the tp (crest) keeps traveling at a high speed. The result f thse cnflicting frces causes the water t rise in height. travel at high speeds f up t 640 km/hr (400 mi/hr) (i.e. a cmmercial jet aircraft travels at km/hr ( mi/hr)) and ffer little time fr warning befre reaching land with devastating frce. Figure 1.1 Hw d tsunamis affect peple and the built envirnment? Destructin happens in tw parts: the smashing impact frce f a wall f water traveling at high speeds, and the destructive pwer f a large vlume f water receding frm the land, taking everything with it. Buildings, bridges, animal habitats, and the general landscape are destryed by the pwerful frce f the water. Large bjects such as ships and bulders can be carried several miles inland befre the tsunami subsides. Once the tsunami waves have kncked dwn infrastructure n the shre, the debris may cntinue t travel fr several miles inland. The debris cllides with ther elements f the built envirnment causing greater damage. Since tsunamis travel very 1

4 Salvadri s Guide t Talking with Yur Students quickly, there is very little time fr peple near the shre t map an escape plan, which ften leads t a high level f fatalities. Figure 1.1 indicates the susceptibility t tsunamis f castlines arund the wrld. New Yrk City is listed as a Lw Risk f Tsunami Zne because the Atlantic Ocean is nt prne t earthquakes. Questins fr discussin Have yu r anyne yu knw ever seen a tsunami? If s, what was it like? If yu feel an earthquake and are near the cast, what shuld yu d? 2

5 Salvadri s Guide t Talking with Yur Students Exercise 1: The Frce f Water In this experiment, yu will bserve and feel that water has cmpressive strength but n shear strength. Yu ll Need (1) water cup (1) plastic knife Water The Exercise Fill the cup 2/3 full f water Take the plastic knife and plunge it int the water; yu ll ntice that the water ffers n nticeable resistance t this actin (see fig. 1.2) Nw mve the knife back and frth alng the thing edge; yu ll ntice that the water still des nt ffer significant resistance FIGURE 1.2 Mve the knife sideways against the brad side f the knife; this time yu ll ntice that it takes sme effrt t push it back and frth ~ this cunter frce is called resistance (see fig. 1.3) FIGURE 1.3 3

6 Salvadri s Guide t Talking with Yur Students Questins fr Yur Students What ther frms f resistance can they describe? Answer: Cupping yur hands while swimming, adding flippers t yur feet, r hlding yur hand in frnt f a mving fan r ut a car windw. Yu can slice thrugh water with the side f yur hand faster than if yu cupped yur hand. This is similar t hw a hand-held fan wrks. The larger surface mves mre air. What d yu think cmpressive strength is? What is shear strength? Answer: Cmpressin is a pushing frce. Cmpressive strength is the resistance a material r structure has t withstand lads (cmpressive strength resists cmpressin). S a hard surface (marble table tp) has a greater cmpressive strength than a sft surface (pillw). The pillw gives mre against the same amunt f cmpressin than the marble table tp. Answer: Shear strength is the magnitude f resistance the particles f a material naturally have. Fr example scissrs (r shears) can easily cut thrugh ne sheet f paper. When yu add sheets f paper, the cmbined shear strength increases. That is why it is harder t cut thrugh five sheets f paper than it is t cut thrugh ne sheet f paper. Hw can yu tell frm this experiment that water has significantly greater cmpressive strength and little shear strength? Answer: It takes effrt fr the brad surface f the knife t mve frm side t side because mvement against the water creates cmpressin. Hwever, when slicing thrugh the water, water particles ffer n resistance. What d the frces f water have t d with tsunamis? Answer: dn t frm n their wn; the cmpressive strength f any given tsunami is determined by external frces. Fr example, the vlume f water filling the vid caused by the sil shifting during an earthquake r a vlcan. The mving sil is similar t mving the brad side f the knife in the glass f water. 4

7 Salvadri s Guide t Talking with Yur Students Exercise 2: Ripple Effect (this links t a vide f a similar experiment) In this experiment, yu will bserve hw water is affected by external frces. Yu ll Need (1) rund cntainer (i.e. bwl r bucket) with a 12 diameter and a depth f at least 6 (1) pencil (like a #2 pencil, ne with an attached eraser) Water The Exercise Fill yur bwl r bucket 3/4 full f water With the eraser side f the pencil, tap the center f the tp f the water Let the water settle Nw tap the edge f the bucket 5

8 Salvadri s Guide t Talking with Yur Students Questins fr Yur Students Why d yu think the cntainer fr this experiment needs t be rund? Answer: Ripples travel radially. A rund cntainer is the best way t see the ripples. What is the difference between tapping the pencil in the center versus the edge f the bucket? Answer: When tapping the center, yu can see the ripple s rigin pint; when tapping the edge f the bucket, it is mre difficult t lcate a central pint f rigin. Imagine the bwl is the sea. What wuld happen if what yu experienced in this exercise happened in a bigger bdy f water? Wuld the built envirnment be affected? Answer: It depends n the size f the bject that is creating the ripples. If it was a small bject, yu might t see smething simple happen, a ripple. If it was a large bject (i.e. a meter) then yu wuld expect t see big waves that culd pssibly crash n the cast and destry buildings. 6

9 Salvadri s Guide t Talking with Yur Students Exercise 3: Tsunami in a Bttle (this links t a vide f the experiment yu can fllw) In this experiment, yu will see the way a wave takes shape, and hw earthquakes affect the size and scpe f waves. Yu ll Need (1) bttle f baby il (1) funnel (1) empty, transparent, and label-free 1 liter bttle Fd dye (preferably blue but any clr will wrk) Water The Exercise Add fd dye t the water and stir until mixed Use the funnel t pur the dyed water int the bttle, filling it halfway (if ding this causes sme bubbles t frm n the surface f the water, let it sit fr a few minutes and they shuld g away) Take the baby il and carefully fill the bttle the rest f the way with il, leaving little t n air left in the bttle Nw that the bttle is filled, seal it as securely as pssible with the lid Take the bttle and turn it n its side Once the bttle has settled n its side, take ne hand and lift the cap side f the bttle slightly; yu ll ntice that it lks like waves turning Let the water settle, then quickly lwer the cap side. What d yu bserve? 7

10 Salvadri s Guide t Talking with Yur Students Questins fr Yur Students What des dyed water represent and what des clear water represent? Answer: dyed water represents water and clear water represents the sky r pen air. Pretend yur hand is ne side f an cean fault. If yu are ging t recreate an earthquake in the bttle, what shuld yur hand d? Answer: Yur hand shuld mve the bttle vigrusly. What d yu see as yu mve the bttle mre? Answer: This varies; but essentially the dyed water shuld mve in bigger waves. Imagine the ther end f the bttle is a beach shre. If yu re at the beach and feel an earthquake, what shuld yu d? Why? Answer: Mve as fast as yu can away frm the shreline; as mentined in the intr, earthquakes can create tsunamis, which can reach the cast as a fast-traveling, huge mass f water. What are the limitatins f the experiment? Wuld yu d anything differently? Answer: This varies; big bdies f water mve differently than liquid inside a bttle; perhaps run the experiment in a bigger bttle. 8

11 Salvadri s Guide t Talking with Yur Students Exercise 4: Water in a Bag In this experiment, yu will be able t measure the distance water travels when frce is applied t it. Yu ll Need (1) rectangular waterprf zip lck bag (2) piece f 8 ½ x 11 cardbard (r smething similarly rigid) (1) sheet f 8 ½ x 11 graph paper Water The Exercise Fill the waterprf zip lck bag 2/3 full f water and lay it flat n a table Place (1) f the pieces f cardbard n the bag hrizntally (parallel t the table) Attach the 8 ½ x 11 graph paper t the ther piece f cardbard Stand the cardbard with graph paper up against the shrt edge f the rectangular bag f water with the graph paper facing the shrt edge Mark n the graph paper where the piece f hrizntal cardbard tuches the paper (withut applying any pressure n the rectangular bag f water) Remve the paper and draw a hrizntal line where yu made the mark (parallel t the bttm f the page) ~ this is yur shreline Sketch a simple neighbrhd n the graph paper where the shreline starts ~ leave rm fr a beach and nrmal changes in tides (abut ½ ) 9

12 Salvadri s Guide t Talking with Yur Students Once yu ve drawn yur neighbrhd, return yur drawing s that it is up against the shrt edge f the rectangular bag f water with the graph paper facing the shrt edge Make sure the 8 ½ x 11 cardbard is n tp f the rectangular bag f water Nw apply light pressure t the far end f the cardbard (ppsite the drawing) that is n the rectangular bag f water Mark where the cardbard tuches the graph 10

13 Salvadri s Guide t Talking with Yur Students Questins fr Yur Students What des the piece f cardbard n tp f the bag represent? Answer: The surface f the water. What des the pressure applied t the end f the bag represent? Answer: Any frce that wuld mve water (i.e. the mn s gravitatinal pull, a vlcanic eruptin under the sea, an earthquake) What happens when yu apply different amunts f pressure t the bag? Answer: A small amunt f pressure resembles a regular tide. A large amunt f pressure wuld represent the height f a wave during a tsunami. What wuld happen t the neighbrhd when the water level rises? Answer: The neighbrhd wuld becme flded 11

14 Salvadri s Guide t Talking with Yur Students Questins t Ask Yur Students Re-cap What is a tsunami? Hw are tsunamis generated? Hw d tsunamis cause damage? Where d tsunamis happen in the United States? Characteristics Hw many waves are there in a tsunami? What is the difference between a tsunami and a wave? Hw fast des a tsunami travel? Hw big is a tsunami? What des a tsunami lk like when it reaches the cast? Hw lng des a tsunami last? Distributin and Frequency f Hw ften d tsunamis ccur? Where can I find infrmatin n the wrld's tsunamis? If earthquakes are n the increase, des that mean tsunamis are as well? If s, why? What was the largest recrded tsunami in wrld histry? In Yur State Where d tsunamis ccur in yur state/cuntry? Hw ften d tsunamis ccur in yur state/cuntry? What is the largest tsunami ever recrded in yur state/cuntry? Fllw-up: Research Tpics fr Yur Students What is the relatinship between tsunamis and ther natural disasters (like earthquakes, landslides, vlcanes, r meters)? Can tsunamis be predicted? Des the rate f tsunamis increase in specific kinds f weather? Are there certain mnths f the year that are mre tsunami-active than thers? 12

15 Salvadri s Guide t Talking with Yur Students Vcabulary Nte: Mst wrds are included (and red/bld) thrughut the text; we als included additinal wrds yur students may hear in the media. Aftershck a small earthquake that fllws the main earthquake Cmpressin a pushing frce Crest the tp f a wave Earthquake Ebb a term used t describe a sudden slip n a fault and the resulting grund shaking and radiated seismic energy caused by the slip; vlcanic r magmatic activity, r ther sudden stress changes in the earth the mvement f the tide ut t sea Energy (specific t tsunamis) a degree r level f energy pssessed by smething r required by a prcess Ersin the gradual destructin r diminutin f smething Fault a break in the earth s crust alng which mvement f the tectnic plates can take place, causing an earthquake Fld an verflwing f a large amunt f water beynd its nrmal cnfines, especially ver what is nrmally dry land Flw the mtin f a gas r liquid 13

16 Salvadri s Guide t Talking with Yur Students Frictin the resistance that ne surface r bject encunters when mving ver anther Intensity a measure f the degree t which an earthquake is felt and the amunt f damage caused by an earthquake Radiate (specific t tsunamis) diverge r spread frm a central pint Resistance a frce (such as frictin) that perates ppsite the directin f mtin f an bject and tends t prevent r slw dwn the bject s mtin Ripple a small wave r series f waves n the surface f water, especially as caused by an bject drpping int it r a breeze Shear strength the strength f a material r cmpnent against the type f yield r structural failure where the material r cmpnent fails in shear Tectnic bundary a bundary between tw r mre tectnic plates Tectnic plates the large, thin, relatively rigid plates that mve in relatin t ne anther n the uter surface f the Earth Tensin a pulling frce Tide the alternate rising and falling f the sea, usually twice in each lunar day at a particular place, due t the attractin f the mn and sun Tsunami an extremely large wave caused by an earthquake 14

17 Salvadri s Guide t Talking with Yur Students Vlcan Wave a muntain r hill, typically cnical, having a crater r vent thrugh which lava, rck fragments, ht vapr, and gas are being r have been erupted frm the earth s crust a lng bdy f water curling int an arched frm and breaking n the shre 15

18 Salvadri s Guide t Talking with Yur Students Resurces Fr mre infrmatin and hands-n activities abut tsunamis, visit Salvadri s stre: Fr mre infrmatin abut tsunamis and tsunami safety, visit: Sme definitins frm the vcabulary sectin f this lessn were taken frm: Fr mre infrmatin abut the Salvadri Center: Phne: thecenter@salvadri.rg 16