Sources and Further Reading

This book makes a great many specific factual claims, and a reader is entitled to a route to the evidence behind them. What follows is that route: a selected reading list, and then chapter-by-chapter notes identifying which sources carry which claims.

One convention needs explaining, and it is the same one the book uses for its arguments.

Entries marked [verified] have been checked directly against the source. Entries marked [to verify] are pointers — I am confident enough in them to send you there, and I have not personally confirmed the volume, page, or in some cases the year. That distinction is unusual to publish. I am publishing it because a book which spends fourteen chapters insisting on the difference between a signal and a certainty cannot then present an unaudited reference list as though every line of it were equally solid.

The [to verify] items are a working list, not a disclaimer. They should be closed before this book is printed, and the intention is that in a finished edition this convention disappears because every entry has become the first kind.

Selected reading

Books for the general reader, grouped by what they are good for. None of these editions has been individually checked; treat the whole section as [to verify] for bibliographic detail, though the works themselves are well known.

On geology as narrative. John McPhee, Annals of the Former World — the collected volume of his geological writing, and the book that established that this material could be told as a story without any loss of rigour. If you read one other book about the Earth, read this.

On deep time as a way of thinking. Marcia Bjornerud, Timefulness: How Thinking Like a Geologist Can Help Save the World — the argument, referenced in the introduction and again in the coda, that temporal literacy is closer to a civic capacity than to an academic specialism.

On volcanoes and human history. Clive Oppenheimer, Eruptions That Shook the World — the standard accessible treatment of volcanic events and their societal consequences, and the natural next book after Part IV of this one.

On the origin of life and its energetics. Nick Lane, The Vital Question: Why Is Life the Way It Is? — the fullest popular statement of the alkaline vent argument set out and then partly withdrawn in Chapter 6. Read it alongside Chapter 6's objections rather than instead of them.

On habitability as a planetary property. James Kasting, How to Find a Habitable Planet — from one of the authors of the 1981 thermostat paper that Chapter 7 is built on.

Reference works. Haraldur Sigurdsson et al. (eds.), The Encyclopedia of Volcanoes — the standard technical compendium, and the place to go for anything in the Appendix. Peter Francis and Clive Oppenheimer, Volcanoes — a university-level textbook that a determined general reader can use.

On Pinatubo specifically. Christopher Newhall and Raymundo Punongbayan (eds.), Fire and Mud: Eruptions and Lahars of Mount Pinatubo, Philippines — the collected scientific account of the events in Chapter 5, published by PHIVOLCS and the USGS and freely available.

Chapter notes

Introduction — The Engine and the Interruption

Paricutín. The eruption began on 20 February 1943; Dionisio Pulido was burning brush in his cornfield. The eruption ran to 1952 and the cone reached 424 m above the field. Both Paricutín and San Juan Parangaricutiro were buried; the church tower survives. No direct fatalities; three deaths from eruption-associated lightning. [verified] — Smithsonian Global Volcanism Program entry for Parícutin; the Oxford Research Encyclopedia of Latin American History article "Parícutin: Volcano in a Cornfield."

The Lost City downgrade is sourced under Chapter 6.

Solar luminosity increase of ~30% over Earth history is sourced under Chapter 7.

Still open: the claim that the Paricutín lava field will carry fertile soil "within a few centuries" — plausible but unchecked, and the weathering timescale for young basalt in that climate may be considerably longer. [to verify]

Chapter 1 — The Rock That Flows

S-waves do not propagate through liquids; the S-wave shadow zone establishes a liquid outer core. Standard seismological result; any introductory geophysics text. [to verify] for a citable primary treatment.

Decompression, flux and heat-transfer melting. Standard igneous petrology. Sigurdsson et al., Encyclopedia of Volcanoes, is the accessible reference. [to verify]

Geoneutrino detection of Earth's radiogenic heat. KamLAND (Japan) and Borexino (Italy). [to verify] — get the specific results papers and state what they actually constrain, since the draft is deliberately vague on magnitude.

The plume debate. W. Jason Morgan's original formulation, early 1970s; the sceptical case associated with Don Anderson and Gillian Foulger; recent tomographic imaging of broad conduits beneath hotspots by Scott French and Barbara Romanowicz (2015). [to verify] — all three attributions.

Kola Superdeep Borehole, ~12,262 m, drilling ceased 1989. [to verify]

Ringwoodite inclusion in a Brazilian diamond, containing water, from the transition zone — Pearson et al., 2014. [to verify]

Bridgmanite formally named in 2014 from a shocked meteorite, because no natural terrestrial specimen existed. [to verify] — confirm the meteorite (Tenham) and the IMA naming requirement.

Chapter 2 — The Physics of the Cork

Volatile solubility, exsolution, fragmentation, and the silica–viscosity relationship. Standard volcanology; Encyclopedia of Volcanoes. [to verify] for specific values — the viscosity range across natural magmas, the crystal fraction at which effective viscosity climbs, and the gas volume fraction at fragmentation.

Nyiragongo's foiditic lava and its flow velocities. [to verify] — see also Chapter 13.

Lake Nyos, 1986, limnic overturn and CO₂ asphyxiation. [to verify] — death toll commonly given as ~1,700–1,800.

Mount St. Helens 1980: sector collapse unroofing the cryptodome and producing the lateral blast. [to verify]

Chapter 3 — The Instrument You Cannot Insert

Unzen, 3 June 1991: 43 fatalities, including Katia and Maurice Krafft and Harry Glicken. [verified]

The Kraffts' footage in the IAVCEI hazard film Understanding Volcanic Hazards, used at Pinatubo briefings with civil defence and military audiences and in the community information campaign. [verified] — USGS, "Pinatubo 1991: emergency management."

Glicken and Johnston at Mount St. Helens — that Glicken was the assigned observer at Coldwater II, left for a meeting with his adviser, and Johnston substituted. [to verify] — widely reported and almost certainly correct in outline, but exactly the kind of account that acquires tidiness in retelling.

The three accidental magma encounters — Kīlauea's lower east rift zone (2005, dacite, ~2.5 km), Krafla IDDP-1 (2009, rhyolite, ~2.1 km), Menengai (2009). [to verify] individually. Note that an earlier draft of the outline said "Kīlauea Iki," which appears to be wrong.

Melt inclusions as pressure gauges; crystal zoning; diffusion chronometry. [to verify] for a citable review.

The Mogi point-source model and the depth/volume trade-off. [to verify]

Chapter 4 — The Death of the Cavern

Crystal mush and the extraction of crystal-poor rhyolite. Olivier Bachmann and George W. Bergantz, "On the Origin of Crystal-poor Rhyolites: Extracted from Batholithic Crystal Mushes," Journal of Petrology 45(8), 2004, 1565–1582. [verified]

Transcrustal magmatic systems. Katharine V. Cashman, R. Stephen J. Sparks and Jonathan D. Blundy, "Vertically extensive and unstable magmatic systems: A unified view of igneous processes," Science 355(6331), 2017, eaag3055. [verified]

Rheological lockup threshold (~50% crystals) and thermal lifetime of an upper-crustal body without recharge. [to verify] — both are volume- and depth-dependent and should be cited to specific modelling work.

Hunga Tonga–Hunga Haʻapai, 15 January 2022: column ~57 km into the mesosphere, highest recorded since Krakatoa 1883; very large stratospheric water vapour injection. [verified]

The instrument list — geostationary satellite cadence, IMS hydroacoustic detection, ionospheric TEC disturbance, lightning rates, global barometric Lamb wave. [to verify] individually.

Chapter 5 — Two Warnings

Nevado del Ruiz and Armero, 13 November 1985. Eruption at 21:09; the first lahar reached Armero at 23:30, an interval of two hours and twenty-one minutes. Armero had ~28,700 inhabitants and about three-quarters were killed; the total across all affected valleys, including ~1,800 at Chinchiná, exceeded 23,000. [verified]

The hazard map, in preliminary form by early October 1985, presented to national, regional and local authorities, correctly showing lahar inundation of Armero. [verified]

The Red Cross evacuation order was issued and not executed — the failure was a loss of electrical power during a thunderstorm, not a countermand. An earlier draft of this chapter implied a deliberate reversal; that was wrong and has been corrected. [verified]

Local officials and radio urging residents to stay calm and remain indoors. [verified] in outline; [to verify] against primary reconstructions rather than encyclopedic summary. The primary literature here is Barry Voight's analyses of the Ruiz disaster and Dennis Mileti's work on the warning system.

Pinatubo, 15 June 1991: USGS/PHIVOLCS estimate that forecasts and evacuations saved between 5,000 and 20,000 lives; approximately 400 died, most from ash-loaded roof collapse. [verified] — USGS Fact Sheet 115-97 and Fire and Mud.

The five-level alert scheme, staged evacuation radii, and Clark Air Base evacuation. [to verify] — Fire and Mud is the source.

The declining SO₂ flux read as sealing and pressurization. [to verify] — confirm this formed part of the 1991 reasoning rather than being retrospective. This claim appears again in the Appendix and the two must agree.

The false-alarm ledger: La Soufrière, Guadeloupe 1976 and the Tazieff/Allègre dispute; Campi Flegrei 1982–84 and the Pozzuoli evacuation; Whakaari/White Island 2019 and its legal aftermath; L'Aquila 2009 and the appeal outcome. [to verify] — all four, and L'Aquila with particular care, as it is frequently misreported in both directions.

Chapter 6 — The Vent at the Beginning of Life

Lost City Hydrothermal Field. Deborah S. Kelley et al., "An off-axis hydrothermal-vent field near the Mid-Atlantic Ridge at 30° N," Nature 412, 2001, 145–149. The field sits ~15 km off the spreading axis on ~1.5 Myr-old crust; carbonate chimneys reach ~60 m, the tallest known; the system is driven by exothermic serpentinization of mantle rock rather than by magmatic heat. [verified] — this is the citation behind Chapter 6's central downgrade.

Fluid properties — roughly 40–90 °C, pH above 9, hydrogen- and methane-rich, poor in CO₂, H₂S and metals. [verified]

The alkaline vent origin hypothesis. Michael Russell's original formulation, developed with William Martin and elaborated by Nick Lane. [to verify] — establish the attribution order before naming anyone in print.

The thioester objection from the Earth-Life Science Institute, arguing that the free energy of thioester hydrolysis makes abiotic accumulation implausible at Lost City conditions. [verified] in substance; [to verify] for the specific paper.

The 1977 Galápagos Rift discovery and the Corliss et al. 1979 Science publication. [to verify], including the vodka-preservation anecdote, which the chapter already flags as the kind of story that improves in retelling.

The subaerial hot spring alternative — Armen Mulkidjanian and colleagues on the K⁺/Na⁺ argument from cytoplasmic composition; David Deamer on wet–dry cycling and vesicle formation. [to verify] — both attributions and the strength of the experimental results.

Deep biosphere mass estimates. [to verify] — figures have been revised substantially; use the most recent synthesis and state its uncertainty.

Chapter 7 — Air, Ocean, Continent

The carbonate–silicate thermostat. James C. G. Walker, P. B. Hays and James F. Kasting, "A negative feedback mechanism for the long-term stabilization of Earth's surface temperature," Journal of Geophysical Research 86(C10), 1981, 9776–9782. [verified] — the load-bearing citation of the entire book.

Roughly half of all radiogenic argon-40 ever produced by potassium-40 decay now resides in the atmosphere. [verified] in substance; [to verify] for a citable primary source. This is the chapter's opening proof and deserves a hard reference.

Solar luminosity has increased by roughly 30% over Earth's history (the Sun at ~70% of present output at 4.5 Ga). [verified] in substance. The faint young Sun problem was posed by Carl Sagan and George Mullen in 1972. [to verify] for the original paper.

Snowball Earth. Paul Hoffman and Daniel Schrag's synthesis; Joseph Kirschvink's earlier formulation of the term; cap carbonates as the predicted post-glacial weathering signature. [to verify] — all three, plus the Sturtian and Marinoan age ranges.

D/H ratios and the provenance of Earth's water. [to verify] — Earth's ocean value, cometary values, carbonaceous chondrite match, and the current balance of evidence.

The geodynamo section. This argues against the textbook account that Earth's magnetic field is why we kept our atmosphere and Mars did not. [to verify] with particular care — Venus's induced magnetosphere, the polar-outflow argument that an intrinsic field may increase loss, and MAVEN results. It is the one place in the chapter contradicting what a general reader will have absorbed.

Chapter 8 — The Dead Worlds and the Icy Ones

Venus's deuterium-to-hydrogen ratio far exceeding Earth's, as the fingerprint of a lost ocean. [to verify] — the ratio is commonly given as ~100–150× terrestrial and the chapter's ocean-loss argument rests on it.

Evidence for ongoing Venusian volcanism — Robert Herrick and Scott Hensley's 2023 reanalysis of Magellan radar showing a vent changing shape between 1990–92 passes at Maat Mons; Venus Express emissivity anomalies; atmospheric SO₂ variability. [to verify] individually.

Olympus Mons dimensions and the stagnant-lid explanation for its size. [to verify]

Enceladus plume composition from Cassini — sodium salts, silica nanoparticles, molecular hydrogen, methane, macromolecular organics; the libration measurement establishing a global ocean. [to verify] — each finding has its own paper.

The Enceladus tidal heating budget shortfall. [to verify] — confirm this remains an open problem.

Europa Clipper and Dragonfly mission timelines. [to verify] and update before publication — both are time-sensitive.

Chapter 9 — Is a Living Planet Necessarily a Firing One?

The current state of temperate rocky exoplanet atmospheric characterization, and the TRAPPIST-1 results consistent with thin or absent atmospheres on the inner planets. [to verify] and update before publication — this is the chapter's main deflationary claim and it is the most time-sensitive statement in the book.

SO₂ as a proposed volcanic geosignature — atmospheric lifetime, the resupply argument, detectability assessments. [to verify]

The claim that no proposed observable directly indicates subduction or tectonic recycling. [to verify] — a strong negative claim carrying the chapter's most original point. Search the literature for proposed tectonic geosignatures before asserting it.

Stagnant-lid habitability modelling. Bradford Foley, Andrew Smye, Nicola Tosi and others. [to verify]

The Gaia critique — that planetary-scale homeostasis lacks a unit of selection. [to verify] — confirm the standard formulation (W. Ford Doolittle and Richard Dawkins are the usual attributions).

The phosphorus argument — apatite weathering as the dominant source, marine burial as the sink, and P-limitation on a tectonically dead planet. [to verify] — confirm this is a real position in the literature rather than an extrapolation.

Chapter 10 — The Caldera Problem

Yellowstone caldera-forming eruptions. Huckleberry Ridge Tuff, ~2.059 Ma, ~2,450 km³; Mesa Falls Tuff, ~1.285 Ma, ~280 km³; Lava Creek Tuff, ~0.639 Ma, ~1,000 km³. Intervals of ~774,000 and ~646,000 years; average ~710,000; elapsed ~639,000. [verified] — these six numbers carry the entire "overdue" argument.

One caveat that remains open: recent ⁴⁰Ar/³⁹Ar work has proposed that the Huckleberry Ridge eruption occurred as multiple pulses rather than a single event, which would alter the interval arithmetic. [to verify]

Bishop Tuff volume (~600 km³) and Long Valley eruption age (~767 ka). [to verify]

Comparative volumes — St. Helens 1980, Pinatubo 1991, Tambora 1815, Toba. [to verify], and note that mixing bulk and dense-rock-equivalent figures is the commonest error in this material; state which is being used.

Zircon age spreads versus diffusion chronometry timescales, and the reconciliation in which the two clocks time different things. [to verify] — cite the specific studies rather than generalizing.

The Toba bottleneck hypothesis and the evidence against it. Stanley Ambrose proposed it in 1998. Michael Petraglia et al., Science, 2007, found Middle Palaeolithic assemblages both below and above the Youngest Toba Tuff at Jwalapuram in southern India, indicating technological continuity across the eruption. [verified] for Petraglia. The Lake Malawi core work and the reinterpretation of bottleneck genetics as dispersal founder effects are [to verify]. Recent work arguing for larger Toba climate effects also needs representing fairly.

Global VEI 8 recurrence estimates, including recent upward revisions. [to verify] — the chapter deliberately avoids a single number; keep it that way unless a well-bounded figure can be given.

Campi Flegrei — population inside the caldera, bradyseism episodes and magnitudes, recent seismicity, and the 1538 Monte Nuovo eruption. [to verify] and update before publication.

Chapter 11 — The Great Dyings

The end-Permian extinction timeline. Seth Burgess and Samuel Bowring et al., "High-precision timeline for Earth's most severe extinction," PNAS 111, 2014, 3316–3321, placing the main extinction phase at no more than ~60,000 years. [verified]

Siberian Traps contact metamorphism. Henrik Svensen, Sverre Planke and colleagues, "Siberian gas venting and the end-Permian environmental crisis" (2009), on sill emplacement into the Tunguska Basin releasing sediment-derived volatiles through contact metamorphism of coal, organic shale and evaporites. [verified] in substance; [to verify] for journal, volume and pages. This is the chapter's central mechanistic claim.

The extinction–LIP ledger. The chapter deliberately rejects the common "four of the five" shorthand. The accompanying thesis paper has been amended to match. [to verify] for each individual association.

The end-Cretaceous dispute — the two 2019 Science dating papers reaching opposite conclusions on Deccan timing (Sprain et al. and Schoene et al.). [to verify], including whether they were indeed same-journal, same-issue.

Extinction magnitude figures. [to verify] — marine species loss estimates have been revised downward from the long-cited 96%.

The rate comparison — end-Permian carbon release versus cumulative anthropogenic release, and the claim that the current rate exceeds anything in the Phanerozoic. [to verify] with care; the rate claim is strong and frequently asserted loosely.

Chapter 12 — Volcanic Winter, and the Temptation to Borrow It

The 1257 eruption. Franck Lavigne et al., "Source of the great A.D. 1257 mystery eruption unveiled, Samalas volcano, Rinjani Volcanic Complex, Indonesia," PNAS, 2013 (doi:10.1073/pnas.1307520110). The identification rests on ice-core sulfate and tephra, radiocarbon dates, tephra geochemistry, stratigraphy, and the Babad Lombok palm-leaf chronicle describing the destruction of the kingdom of Pamatan. [verified]

The 536 sequence. Michael Sigl et al., "Timing and climate forcing of volcanic eruptions for the past 2,500 years," Nature 523, 2015, 543–549 — the ice-core chronology revision aligning volcanic signals with tree-ring cooling. Ulf Büntgen et al., "Cooling and societal change during the Late Antique Little Ice Age from 536 to around 660 AD," Nature Geoscience, 2016, identifying an eruption cluster in 536, 540 and 547. [verified] for both.

Laki, 1783–84 — fissure length, duration, lava volume, sulfur release, Icelandic livestock and human mortality, and the English excess-mortality analyses. [to verify] throughout.

The Laki–French Revolution claim, which the chapter declines to endorse. [to verify] that historians of the period are indeed generally unpersuaded, rather than assuming it.

Tambora 1815 and the year without a summer, including the Villa Diodati and Frankenstein connection and the Drais running-machine/oat-shortage story. [to verify] — the Drais causal link in particular is widely repeated and should not be assumed.

Hunga Tonga's radiative sign. Earlier studies reported net warming from the stratospheric water vapour injection; more recent work indicates a slight net cooling. The sign is disputed. [verified] that the dispute exists; [to verify] for the specific papers on each side.

Eyjafjallajökull 2010 — flights cancelled, passengers affected, industry cost; and the 1982 British Airways Flight 9 and 1989 KLM 867 engine-failure incidents that established the ash hazard. [to verify]

Pinatubo as the solar geoengineering design document — ~20 Mt SO₂, ~0.5 °C cooling, 1–2 year aerosol residence; subsequent ozone depletion; the post-Pinatubo decline in global precipitation and continental river discharge. [to verify] — the precipitation finding is usually attributed to Kevin Trenberth and Aiguo Dai (2007).

The Yellowstone heat-extraction proposal and its arithmetic. [to verify] — the chapter's dismissal is confident and must be defensible.

Heimaey 1973 — the volume of seawater pumped and the extent to which the intervention determined the outcome versus the eruption ending on its own. [to verify] — this is the chapter's one success story and should not be overstated.

Chapter 13 — Who Lives on the Flank

Global volcanic exposure figures — ~800 million within 100 km of a Holocene-active volcano; ~200 million within 30 km. [to verify] — source to the Global Volcano Model / VOGRIPA population exposure work (Brown et al.) and state the definition used.

Andisol mineralogy — short-range-order minerals, high specific surface area, water retention, cation exchange capacity — and the phosphorus fixation limitation the chapter raises as its honest complication. [to verify]

Roman concrete and pozzolana, and the seawater durability mechanism. [to verify] — the mineralogical understanding has been refined recently.

Goma and Nyiragongo — the 1977, 2002 and 2021 eruptions; lava flow velocities and the foidite composition; Goma's population and its conflict-driven growth. [to verify]

The Goma Volcano Observatory funding suspension preceding the May 2021 eruption, and its operational consequences. [to verify] with particular care — this is a serious claim about an institution and a funder, and the chapter's argument about political economy depends on it being stated fairly.

The Ibagué funeral banner — "The volcano didn't kill 22,000 people. The government killed them." [verified] in substance; [to verify] for the original reporting.

The Palace of Justice siege, Bogotá, 6 November 1985, one week before the eruption. [to verify] — used to argue about state capacity, so the connection should be defensible rather than merely suggestive.

Merapi and the office of juru kunci, and the 2006 and 2010 episodes. [to verify] — the chapter deliberately does not name the office-holder; do so only after verifying both episodes.

Simeulue and the smong oral tradition in 2004. [to verify]

Cerén (~600 CE) and the absence of human remains implying evacuation; the qualification that Minoan civilization persisted well after Thera. [to verify]

Evacuation compliance literature — livestock as the dominant return factor, and the finding that community involvement in planning improves compliance. [to verify] — cite the specific studies.

Chapter 14 — Tapping the Furnace

CarbFix carbon mineralization. Juerg Matter et al., "Rapid carbon mineralization for permanent disposal of anthropogenic carbon dioxide emissions," Science, 2016 (doi:10.1126/science.aad8132). Over 95% of injected CO₂ mineralized in under two years, at injection depths of 400–800 m in basaltic lavas and hyaloclastites. [verified]

Pohang, 15 November 2017. An earthquake of moment magnitude 5.4 near an EGS site; 82 injured; the most damaging earthquake recorded in South Korea since instrumental observation began in 1905, and the largest known induced earthquake at any enhanced geothermal site. A Korean government commission concluded in 2019 that it was triggered by fluid injection at the project. [verified] — see also Woo et al., Journal of Geophysical Research: Solid Earth, 2019, and the Science assessment by Kim et al., 2018.

Basel 2006 — induced magnitude ~3.4, damage claims, project suspension and abandonment. [to verify]

IDDP-1 at Krafla (2009) — magma at ~2.1 km against a 4.5 km target, steam at ~450 °C, highest enthalpy geothermal well recorded, and the corrosion failure that ended it. IDDP-2 at Reykjanes (2017) — depth and supercritical conditions. [to verify] both; keep consistent with Chapter 3.

The Krafla Magma Testbed — project status, funding and target drilling date. [to verify] and update before publication.

Global installed geothermal capacity (~16 GW), capacity factors (75–90%), and the Kenyan geothermal share. [to verify] and update to the most recent year. The Kenyan figure in particular is quoted variously and should be given with its basis stated.

Larderello — 1904 demonstration by Piero Ginori Conti, 1913 first commercial plant. [to verify], and the Dante association is traditional and possibly apocryphal — cut it if unsupported.

Ore deposits — porphyry copper and molybdenum, epithermal gold and silver, volcanogenic massive sulfides and the Cyprus etymology, carbonatite-hosted rare earths, Ol Doinyo Lengai as the only active carbonatite volcano, and Salton Sea lithium-from-brine. [to verify] individually.

Coda — The Deep-Time Horizon

The lifespan of the biosphere. Ken Caldeira and James Kasting, "The life span of the biosphere revisited," Nature 360, 1992, 721–723. The most common photosynthetic pathway fails below ~150 ppm CO₂; a second pathway used by a minority of plants operates down to ~10 ppm, which extends the biosphere's remaining lifespan to roughly 900 million years. [verified]

Note: more recent modelling of atmospheric deoxygenation arrives at a comparable horizon, and some very recent work extends the outer bound further. [to verify] and update, since this is the coda's central number.

Isotope half-lives — U-238 (~4.47 Gyr), U-235 (~704 Myr), Th-232 (~14.05 Gyr), K-40 (~1.25 Gyr). [to verify]

The ocean-into-mantle argument — that subduction may return less water than it consumes, potentially stalling plate tectonics before thermal decline does. [to verify] — this is one position among several and the chapter's hedging should be checked as adequate.

Solar luminosity increase of ~1% per 110 Myr. [to verify] — reconcile with the ~30% total figure used in Chapter 7 and the Introduction.

Appendix — Field Protocols

The technical content of Protocols One to Three is standard monitoring practice and can be sourced to the Encyclopedia of Volcanoes and to observatory handbooks. [to verify] — because the appendix presents this material as usable guidance rather than description, it should be reviewed by a working observatory scientist before publication. That is a higher bar than applies to the narrative chapters, and it is the single most important outstanding item in this list.

Event classification — volcano-tectonic, long-period, hybrid, tremor, very-long-period and drumbeat seismicity, with Mount St. Helens 2004–2008 as the drumbeat type example. [to verify]

The amplitude-averaging measure described but not named in the text (RSAM), and its development during a real crisis. [to verify] before naming and attributing it.

Volatile solubility ordering as a depth proxy, and the declining-SO₂-as-sealing interpretation. [to verify] — the latter must agree with Chapter 5.

Pinatubo lives-saved range (5,000–20,000). [verified]

Compiled alongside the manuscript. Fourteen entries are verified against source; the remainder are pointers awaiting confirmation. The list of what has not been checked is, for the moment, longer than the list of what has — which is an accurate description of the state of this draft and not a comfortable one.