Volcanic risk worksheet

Volcano Scenarios: Disaster Risk Reduction Study You’re a geologists at a geophysical consulting firm who has sent a team into the field to collect samples from a site that may or may not be a hazardous volcano. The team has returned with samples, field observations, and map sketches, and your job is now to assemble the evidence and create a hypothesis about the kind of volcano the residents live by, and to assess risk of eruption, and communicate risk to the residents. Objectives : at the end of this lab, students will be able to:  Correctly identify and give field names to extrusive igneous rocks based on size, texture, color, and minerals present. Use the types of rocks to verify the type of volcano.  Correctly identify the type of volcano from the shape and size, or the height and width of the volcano, as measured on a topographic map.  Correctly identify volcanic deposits, such as pyroclastic flows, ash falls, and lahars, from pictures.  Identify the specific hazards of a volcano based on the type of volcano, the map, the rock types, the chemical compositions of the rocks, and the observed activity on the volcano.  Make a reasonable hazard map for a volcano and provide appropriate explanation.  Make a reasonable plan for communicating the risk of the volcanic hazards. Materials: This Lab Handout; maps of the volcano and surrounding area; ruler and calculator; rock samples collected from volcanic deposits; information about identifying volcanic rocks (from last weeks); field observations and pictures of volcanic deposits in the area (handout) PART 1: Identifying the volcano Question 1: Identify the volcano(s) on your map. The choices are (only one of four): shield volcano stratovolcano Shield volcanoes and stratovolcanoes have different shapes and different slopes (look back at Lab 2 to refresh your memory). The ratio of (the height of the volcano ÷ the half-width of the base) is a way to tell whether the volcano is a shield or stratovolcano. Elevation of summit Height of volcano = (Elevation of summit) – (elevation of base) Elevation of base Half-width of base (elevation of summit) – (elevation of base) = height in feet Height of volcano = _________________ - _____________ = ________________. Convert the height from feet to meters: (height in meters) x (0.3048). Height of volcano in feet = ____________ x 0.3048 = ______________ m. Use the map and ruler to measure the half-width of the volcano base = __________________ km.

Calculate the ratio of the height of the volcano ÷ the half-width of the base. Remember to use the same units (either meters or kilometers) ________________ ÷ __________________ = ___________________. A shield volcano has a ratio value less than 0.18, typically about 0.10. This ratio gives the shield volcano a gentle slope, less than 10° and usually about 5°. A stratovolcano has a higher ratio , greater than 0.18, even as much as 0.25. This gives the stratovolcano a steeper slope, greater than 10° and usually about 15°. Based on your calculation, the volcano is a _____________________________________. If your volcano is not a stratovolcano or a shield volcano, identify the type and explain your reasoning based on the map. Give your volcano a name: _____________________________________. PART 2: Identifying the volcanic rocks. No. Color Texture (all that apply) Minerals or other material in rock Size Rocktype

Question 7: Make one or more hazard map(s) of your volcano. Copy and paste the map provided in the PowerPoint file, and the information you have in this sheet. In which direction is an eruption likely to have the most impact? Draw on the map an indication of which areas are likely to be affected. In the space below, write a neat legend for your map. Also in the space below, summarize all of your assumptions and decisions.

PART 4: Vulnerability to volcanic hazards Question 8: Consider the human activity and infrastructure around your volcano. What are the likely attitudes and behaviors of the people in the area toward the volcano? In the space below, list some values and attitudes that are most likely for your scenario and explain your reasoning. Question 9: Discuss how people’s attitudes and values might influence their ability to understand and be prepared for the volcanic hazards. Sketch out a plan for communicating information, for emergency response, and for evacuation, if necessary. How can you reach the people in the region, and how might you phrase the information?