Effects of Volcanic Eruptions

Transcription

1 DRAFT VERSION 03/09/06 - DRAFT VERSION 03/09/06 - DRAFT VERSION 03/0906 This prject was made pssible thrugh the Institute f Museum and Library Services Natinal Leadership Grant fr Museum and Library Cllabratin Effects f Vlcanic Eruptins This activity cmplements the Mt. St. Helens and the Vlcanic Cascades DVD presentatin and general study guide. GRADE LEVEL Junir High (with extensins fr High Schlers) TIME REQUIRED 3 t 5 classrm sessins (based n 50 minute sessins) ACTIVITY OBJECTIVES Students will learn: The effects f a vlcanic eruptin n a cmmunity. The effects f a vlcanic eruptin n the Earth s envirnment and gelgical structure. The different gelgical features/events f a vlcanic eruptin. Abut the pssible warning signs f a vlcanic eruptin. MATERIALS Map f yur area (see Prcedure n. 2) Access t research materials f lcal muntains (see Prcedure n. 3) Ntebk paper Access t cmputer and printer Phtgraph by Dn L. Hunter Mt. St. Helens, May 18,

2 PROCEDURE (NOTE: THESE ARE SUGGESTED STEPS AND CAN BE MODIFIED ACCORDING TO INSTRUCTOR NEEDS AND RESOURCES) 1. Divide the class int grups f 2-8 (depending n class size). 2. Using a map f the area, each grup will determine the clsest muntain t yur cmmunity. (Nte: If a pssible vlcan is nt a realistic ptin fr yur lcal cmmunity, see the Extensins sectin fr pssible replacement activities.) 3. Research that muntain. Is it extinct, drmant, r active as a vlcan? When was the last time it erupted, if ever? What type f vlcan is it? (See terms.) If it erupted in the dcumented past, hw did it affect the area arund it? 4. Grups will dcument a fictinal vlcanic eruptin f the muntain chsen in # 2 abve. Students will write an utline that describes the varius effects f a vlcanic eruptin n their lcal cmmunity. It is imprtant t take past eruptins int cnsideratin (if applicable). The utline will explain: The extent f: Lava flw destructin Ash fall Changes in the climate Other vlcanic disturbances (earthquakes, mud flws/slides, pyrclastic flws, gases, etc.) The effects n: Human-built structures Human health Agriculture Livestck Frests Landscape (change in land frmatins) 5. Grups will act as vlcanic experts in a mck Twn Hall meeting where they will warn the lcal cmmunity f a pending eruptin. They will create and present a reprt (2-3 pages) t the cmmunity. Taking the utline described abve as a guide, the reprt will include: a. The effects the eruptin will have n the cmmunity and the histrical precedence (if any) f the muntain erupting. b. What shuld city fficials d t ensure the lss f lives and prperty is minimized? c. What shuld individual residents d? Shuld they: Evacuate the cmmunity? Hw far d they need t g t be safe? Bring animals indrs? Fr hw lng? Stre fd and water? Avid driving? Fr hw lng? Other? d. Explain the lng-term changes t the envirnment, and hw it will bunce back. e. Additinally, grups shuld anticipate the types f questins cmmunity residents wuld ask abut the vlcan. 2

3 QUESTIONS FOR CLASS DISCUSSION 1. What types f vlcanic effects did yu fcus n? Hw d they affect a cmmunity? Hw d they affect the natural envirnment? Hw des a vlcanic eruptin fit int the natural cycle f envirnmental changes? 2. D yu think vlcanes r human ppulatins have mre impact n the envirnment? Why des ne have mre impact? What are the negative and psitive effects by bth vlcanes and humans n the envirnment? 3. What is the mst damaging part f a vlcanic eruptin (lava flw, pyrclastic flw, ash, bmbs, etc.)? Think abut damage in terms f lives lst, prperty damage, r ecnmic disruptin (change f flight paths, etc.). Frm yur analysis f the nearest vlcan, what is the mst damaging part f an eruptin in yur area? 4. What types f ccupatins wuld be directly affected by a vlcanic eruptin? What types wuld be indirectly affected? Wuld yur jb r yur parent s jb(s) be affected if the nearest vlcan erupted? 5. Are there ther large-scale natural ccurrences that affect cmmunities n such large scales? What are they? What are the differences and similarities amng these ccurrences and vlcanic eruptins? ASSESSMENT Student assessment may be based n the fllwing specific exercises r in cmbinatin: Student utlines evaluated in terms f cnveying the fllwing infrmatin: The extent f damage and envirnmental change created by vlcanic eruptin. The effects this damage and change has n varius ppulatins (human, animal, plant, etc.) and n the landscape. Grup presentatins fr mck Twn Hall meeting : Was the grup able t accurately describe the extent f the effects f vlcanic damage n the cmmunity? Were the grup s recmmendatins reasnable and clear fr the cmmunity? Did the grup answer the cmmunity s questins in an articulate and accurate manner? Cmpletin f final presentatin written paper (2 3 pages) sufficiently addressing: 1) The effects the eruptin will have n the cmmunity and the histrical precedence f the muntain erupting. 2) What city fficials shuld d t minimize the damage caused by an eruptin. 3) What individual residents shuld d. 4) General cnclusins. Participatin in class discussin. Matching final student knwledge f the tpics in relatin t yur state standards. 3

4 EXTENSIONS Watch the DVD presentatin, Mt. St. Helens and the Vlcanic Cascades by Dn L. Hunter, and have a class discussin arund the tpics presented. Have students research and cmplete the same activity as previusly utlined in the Prcedure sectin, but instead pick a city (nt their wn) with a vlcan clse t it. Hw did the eruptin affect this city? Did the cmmunity d anything t try t avid a ptential disaster? Is a similar scenari pssible in yur cmmunity? Examples: Yakima, WA Mt. St. Helens (1980), ashfall hazard Outskirts f Hil, Hawaii dwnslpe frm Mauna La (1984), lava flw hazard East f Lassen Vlcan, Califrnia near Lassen Peak ( ), ashfall hazard Find ut which natural disaster is mst likely in yur area. Research what the safety plan is if that disaster threatened yur area. Have students research hw vlcanic eruptins assist scientists/archaelgists in learning abut past human ppulatins and their lifestyles. Have students graph ut a certain effect f vlcanic eruptins (such as the distributin f ash patterns) in the Cascades ver the last 10,000 years. Have students research and present n specific Federal Gvernment agencies invlved with the mnitring f natural disasters and hw the agency is invlved directly in the students cmmunity. Have students create a hazard map f their cmmunity and use tpgraphy, vent lcatins, and ptential eruptins styles t map ut pssible effects f a vlcanic eruptin. 4

5 TERMS Ash: Fine material (less than 1/10 an inch in diameter) ejected in an explsive vlcanic eruptin, which can cntain vlcanic glass, crystals, and pulverized rck frm the walls f the vlcanic cnduit. These particles are transprted by wind frm the vlcanic vent int the atmsphere where they can spread fr thusands f miles. Vlcanic ash is the mst widespread hazard frm vlcanic eruptins because f the large areas it can affect. Vlcanic Ash, Mt. St. Helens Phtgraph by Dn L. Hunter Ashfall (Airfall includes pumice): Ashfall is the ash that falls frm the eruptin clud f a vlcan, creating layers f ash n the surface f the Earth. Ash Flw: see pyrclastic flw (belw). Climatic Effects Of Vlcanic Eruptins: Ozne Effect is the destructin f earth s zne by the intrductin f such chemicals as vlcanic aersl gas particles (r human made CFCs). These chemicals create a hle in earth s zne layer, which allws harmful ultravilet rays frm the sun t enter the Earth s atmsphere. Vlcanic effects n zne depletin are minimal and shrt lived due t the fact that the aersl gas particles will dissipate in tw t three years. Greenhuse Effect is caused by the additin f gases (primarily CO 2 and water vapr) t earth s atmsphere. The effect causes a rise in glbal temperatures; CO 2 mlecules allw shrt wavelength slar radiatin t enter the atmsphere, but absrb lng wavelength infrared radiatin frm the earth s surface, thereby trapping heat energy that creates a cycle where mre radiatin is allwed int the atmsphere than is released. Vlcanic eruptins add t glbal warming by adding CO 2 t the atmsphere. Scientists have determined that the amunt f glbal warming caused by eruptin-generated greenhuse gases is small. Haze Effect is caused by airbrne particles frm vlcanic eruptins that blck ut enugh sunlight t cause a reductin in glbal temperatures. Lave tube: A hllw tube in a lava flw frmed by drainage f lava after the frmatin f a slid surface crust. Fissure: A surface fracture r crack in rcks; fissures can be lcated n vlcanic slpes r n active lava dmes. Sme vlcanic eruptins riginate alng elngated fissures, instead f central vent structures. Phtgraph by Dn L. Hunter Pyrclastic Flw: A ht gas-supprted flw f ash, pumice, and rck particles that cllapse ut f a vlcanic ash clumn, r bil-ver frm a vlcanic vent. These flws travel dwnslpe at high speeds causing an extreme asphyxiatin and burn danger fr individuals in the flw path. Splintered Tree, Mt. St. Helens, May 18, 1980 Eruptin DRAFT VERSION 03/09/06 - DRAFT VERSION 03/09/06 - DRAFT VERSION 03/09/03 5

6 Vlcanic Gases: At depth, varius species f gases are disslved in magma. As this magma rises, these species exslve (escape) frm the magma (frm gas bubbles). Sme f these gases are txic and very harmful and thers nt as harmful. Examples in general rder f abundance include: Water Vapr (H 2 0), Carbn Dixide (C0 2 ) Sulfur Dixide (S0 2 ) Hydrgen Sulfide (H 2 S) Hydrgen (H 2 ) Carbn Mnxide (CO) Hydrgen Chlride (HCL) Hydrgen Fluride (HF) Helium (He) Carbn dixide, sulfur dixide, and hydrgen fluride are the gases that pse the largest hazards t humans, animals, and the envirnment. The main effects include: Carbn Dixide (C0 2 ) - In large cncentratins, C0 2 is lethal t humans, animals, and plants. Breathing in air cntaining mre than 30% C0 2 can be deadly t humans and animals, and C0 2 cncentratins in sil abve 20% can be txic t plants and trees. Sulfur Dixide (S0 2 ) - S0 2 causes acid rain and dwnwind air pllutin, and can cntribute t zne and haze effects glbally. Hydrgen Fluride (HF) - HF mlecules can attach t ash particles, which can settle n plants. The acidic txin can kill animals wh eat the ash cated plants. Vlcanism: The prcess in which magma frm beneath earth s surface is brught t the surface. In the Cascades, vlcanism is a result f a release f fluids frm the subducted Juan de Fuca plate beneath the Nrth American plate; these fluids lwer the melting temperature f rcks deep in the Nrth America plate, which then pushes the magma upwards t the surface. Three Main Vlcan Types: Cmpsite Vlcanes r Stratvlcanes have been built up ver thusands f years and are cmpsed f alternating layers f lava flws, vlcanic ash, and fragments f explsively generated vlcanic material, which can rise ver 8,000 feet abve their base. Many famus vlcanes/muntains, such as Munt St. Helens, Munt Hd, Munt Shasta (Cascades, Nrth America), and Munt Fuji (Japan), are stratvlcanes. Shield vlcanes are built almst entirely ut f fluid lava flws. Such lava flws accumulatins can frm large dmes tens f thusands f feet frm base t summit. The Hawaiian Islands are made up f shield vlcanes. Cinder and Scria Cnes are built frm accumulated explsive vlcanic fragments (cinders), which pile up arund a vlcanic vent. These types f vlcanes d nt nrmally rise mre than several hundred feet abve the surface, and can be part f a larger cmpsite cne r stratvlcan. Scientists have identified arund 100 cinder cnes n the sides f Mauna Kea shield vlcan in Hawaii. 6