Volcanic Eruptions and Earthquakes

1. Period 1: Presentation slides 1-8 (the Loma Prieta and Bay Bridge phenomenon, targets, the global pattern, the five settings, how solid rock melts, vocabulary, first check). W1 phenomenon worksheet as the opener (it may run into Period 2 or go home).
2. Period 2: Lab 1, The Unlabeled Map: groups plot 40 simulated earthquakes and 11 volcanoes, draw a depth cross-section, classify the hidden boundaries and rank four towns by earthquake hazard. Debrief reveals the map is loosely modeled on western North America.
3. Period 3: Slides 9-16 (runny and thick magma, the stick-build-slip cycle, focus, epicenter and seismic waves, the logarithmic magnitude scale, two vocabulary slides, the energy check). W2 vocabulary once all twelve terms have been introduced, and W3 reading as homework.
4. Period 4: Slides 17-23 (precursors and the Eyjafjallajokull story, the monitoring-data task, why earthquakes are forecast rather than predicted, the real Bay Area forecast and ShakeAlert, the forecast discussion, California's three hazards, check). W4 diagram and W5 data worksheets (one in class, one as homework or in an added period).
5. Period 5: Slides 24-25 (mitigation, criteria and constraints, the performance-target table, the 'build everything to survive anything' discussion). Lab 2 session 1: groups draw an importance card, write precise criteria and constraints, practice the measured shaking levels and build version 1.
6. Period 6: Lab 2 session 2: test at three shaking levels, pool the class results, identify the features of the best performers, redesign one feature and retest. W8 collaborative jigsaw in an added period or in place of the retest if time is short.
7. Period 7: Lab 3, Three Crossings, One Bridge: rank three sites by hazard risk from simulated data, check the budget and recommend a site and performance target. W6 CER and W7 misconception repair as homework or in the following period.
8. Period 8: Slides 26-28 (the logarithmic misconception, synthesis, exit ticket). W10 mastery as the quiz; W9 transfer as an extension or homework design task.

Materials overview: Lab 1 and Lab 3 are paper only: printed data tables and grids, colored pencils (three colors), rulers and calculators. Lab 2 needs, per group, a rimmed baking sheet or cafeteria tray, a piece of stiff cardboard for the moving deck, six round pencils or dowels as rollers, two latex-free rubber bands and binder clips to center the deck, two small boxes or blocks as river banks, 40 craft sticks, masking tape, paper clips, string, index cards, 40 pennies in a zip bag as the load, a ruler, a phone metronome and safety goggles. No flames, heat or chemicals.

• Multilingual learners: Pre-teach focus, epicenter, magma, lava, forecast and predict with a labeled cross-section and gestures (fist for the focus, finger straight up for the epicenter). Post a word wall pairing everyday and science words (shake / seismic wave; size / magnitude; how often / frequency). Provide frames: 'The quakes here are shallow/deep and there are/are no volcanoes, so this boundary is ___.' and 'An M__ releases about ___ times the energy of an M__ because ___.'
• Students who need more support: In Lab 1 give a map with the ridge points already plotted and a color key printed on the sheet; split the data table so each student plots ten points. Supply a powers-of-ten ladder (1, 10, 100, 1,000) and a powers-of-32 ladder (1, 32, about 1,000, about 32,000) for magnitude comparisons. In Lab 3 pre-fill the scoring table's first row as a worked example.
• Students ready for extension: Estimate the dip angle of the sinking plate from the Lab 1 cross-section; research how the 1700 Cascadia earthquake was dated from Japanese tsunami records and drowned forests; compute the rough peak acceleration of each Lab 2 shaking level from stroke and beat rate; or read about why Long Valley Caldera's unrest since 1980 has not led to an eruption.
• Students who need movement or alternative output: Model stick-slip with two rough boards or a brick pulled on sandpaper by a rubber band, and have students time the jerks. Let Lab 1 plotting happen on a floor-sized masking-tape grid with sticky notes. Accept spoken or recorded explanations and labeled photos of the Lab 2 bridge as evidence.
• Students with low vision or limited fine-motor control: Provide an enlarged Lab 1 grid with raised dot stickers for the three depth classes. In Lab 2 assign the measurer or recorder role with a large-print ruler, and let a partner handle tape and sticks while the student directs the build.

• Melting at subduction zones: Section 1 and Figure 1A (p. 330) and the Key Science Concept (p. 339) say crustal material from the sinking plate mixes with mantle rock and lowers its melting temperature. The main trigger is water (and other volatiles) released from the sinking plate into the hot mantle rock above it. Teach 'water from the sinking plate lets the hot mantle rock above it melt at a lower temperature.'
• Hot spots: Figure 1A (p. 330) and the spread (p. 338) describe rising 'columns of magma' that heat the rock near the surface. A mantle plume is mostly solid rock that is hotter than its surroundings; it partly melts as it rises and the pressure on it drops. How deep plumes start, and whether hot spots stay fixed, are still debated, so the chapter says 'from deep in the mantle' without a depth.
• The mantle is mostly solid: nothing in the lesson says so directly, and students often picture a magma ocean. Every slide on melting states that magma forms only in special settings.
• Eruption styles: Section 1 (p. 331) calls nonexplosive eruptions the most frequent kind and says they do less damage. Many small eruptions are mildly explosive (for example the bursts that build cinder cones), so the chapter does not repeat the 'most common' claim. Lava flows rarely kill people but destroy most property in their path; the lesson's own Eldfell example (more than 400 buildings) was largely a lava eruption. Teach 'usually less deadly', not 'harmless'. Thicker magma is usually richer in silica; explosiveness depends on how much gas the magma holds and whether the gas can escape.
• Predicting eruptions: Section 2 and the Lesson Summary say scientists 'can predict' eruptions. Precursors raise the likelihood, but unrest can last weeks to years or fade with no eruption, and some steam-driven eruptions give almost no warning. The chapter says 'forecast' and 'more likely'.
• Eyjafjallajokull 2010 (p. 332): the eruption began late on March 20, 2010, after weeks of earthquakes and measurable swelling; about 500 residents were evacuated once it had started, and about 800 more when the larger summit eruption began in April. The textbook's statement that people reached safety before the eruption overstates the warning. The defensible point is that months of monitored unrest had communities prepared. The book's 'eleven weeks of swelling' and 'small earthquakes in 2009' are approximate; do not assess them.
• Earthquake precursors: Section 4 and the spread say earthquakes have no precursor events. More precisely, no reliable precursor is known. Some large earthquakes follow foreshocks, but foreshocks cannot be recognized as such until the main shock happens, and claimed precursors often occur with no earthquake following. Earthquake early warning (ShakeAlert, delivered in California through the MyShake app and phone alerts) is not prediction; it detects an earthquake already under way and gives seconds to tens of seconds of notice depending on distance.
• Depth at convergent boundaries: Section 3 and Figure 3A (p. 334) call convergent-boundary earthquakes 'deep'. Subduction zones produce shallow earthquakes too, including the largest megathrust earthquakes on the locked plate contact (shallower than about 50 km); they are the only setting that also produces earthquakes down to about 700 km. Lab 1's data shows both.
• Body waves and damage: Section 3 (p. 335) says body waves are often too weak to feel and that surface waves do the most damage. P waves are usually mild, but S waves, which are body waves, can shake the ground violently near the source; USGS describes S waves and surface waves together as the damaging waves. The chapter says the slower S waves and surface waves cause most of the damage.
• Epicenter and shaking: the lesson says the epicenter is commonly where shaking is most intense. That is a tendency, not a rule; soft ground amplifies shaking. In 1989 the Cypress Street Viaduct (Oakland) and the Marina District (San Francisco), both on bay mud or artificial fill roughly 100 km from the epicenter, suffered some of the worst damage.
• Magnitude versus intensity: the lesson defines magnitude as 'the strength, or intensity' of an event. Seismologists separate the two: magnitude is one number for the earthquake's size at its source; intensity (the Modified Mercalli scale, Roman numerals I to XII) describes shaking and damage at a particular place and differs from place to place. Magnitudes today are usually moment magnitudes, not the original Richter scale, though news reports still say 'Richter'. Each whole step means 10 times the recorded ground motion and about 32 times the energy. Eruptions are sized with a different logarithmic scale, the Volcanic Explosivity Index (0 to 8).
• Dated or approximate figures in the lesson (Iceland's count of about 35 active volcanoes, more than 400 buildings at Eldfell, about 1,500 noticeable earthquakes a year in Japan, the Kobe earthquake's 20 seconds and more than 6,400 deaths, pyroclastic flows faster than 80 km per hour) are not assessed. The Bay Area rates on p. 340 (moderate quakes two or three times a year, strong ones about every seven years) are the book's illustration and do not match USGS forecasts; the chapter uses the USGS Bay Area forecast instead (2014-2043: 98 percent chance of at least one M6.0 or larger, 72 percent for M6.7, 51 percent for M7.0, 20 percent for M7.5).
• Bay Bridge criteria (pp. 340-341): the lesson is not internally consistent. Page 340 and the photo caption say a safety-critical bridge must stay fully operational in very strong, very rare earthquakes, while the p. 341 text allows minor damage in rare strong quakes, and the chart labels two different cells of one column 'safety critical'. The chapter's own performance-target table (slide 24, Lab 2, Lab 3) is self-consistent and does not ask which cell of the book's chart fits the Bay Bridge. The new eastern span's design goals (the strongest shaking expected in about 1,500 years; a 150-year design life) were checked against a Metropolitan Transportation Commission fact sheet.
• California facts used in the chapter: the San Andreas Fault is a transform boundary between the Pacific and North American plates, which move past each other at about 5 cm per year across the whole boundary zone, with the San Andreas taking only part of that motion; its earthquakes are shallow and it has no volcanoes. The Cascadia subduction zone runs about 1,000 km from Cape Mendocino in northern California to Vancouver Island, where the Juan de Fuca Plate (with the smaller Gorda Plate in the south) sinks beneath North America; its last great earthquake, on January 26, 1700, was about magnitude 9 and was dated partly from tsunami records in Japan. It feeds the Cascade volcanoes, including Mount Shasta and Lassen Peak (which erupted from 1914 to 1917). Long Valley Caldera, near Mammoth Lakes, is a 16 by 32 km depression left by a huge eruption about 760,000 years ago; it has had earthquake swarms, ground uplift and gas emissions since 1980, and the youngest eruptions nearby, along the Mono-Inyo chain and in Mono Lake, are only a few hundred years old. USGS rates Mount Shasta, Lassen Volcanic Center and Long Valley Caldera as very high threat; that ranking measures potential impact, not which volcano will erupt next. Long Valley is not at a plate boundary or a classic hot spot; its volcanism is linked to the stretching of the crust east of the Sierra Nevada, so it is presented as an exception.
• Emergency advice: the spread's 'Preparing for' boxes are personal emergency instructions. The chapter treats mitigation as science and engineering (hazard maps, land use, monitoring, building design, early warning) and refers students to their school and family plans rather than writing new disaster advice. Mentioning 'Drop, Cover, and Hold On', the action ShakeAlert messages recommend, is fine.
• All lab and slide datasets other than the USGS Bay Area forecast table are simulated teaching data and are labeled that way. The Lab 1 map is fictional, loosely modeled on western North America; the Lab 3 county, fault and volcano are fictional.