Chris Newhall

Chris Newhall
ex USGS, NTU

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78
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Introduction
Skills and Expertise

Publications

Publications (78)
Article
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Here, we review volcanic risk management at Mount St. Helens from the perspective of the US Geological Survey’s (USGS) experience over the four decades since its 18 May 1980 climactic eruption. Prior to 1980, volcano monitoring, multidisciplinary eruption forecasting, and interagency coordination for eruption response were new to the Cascade Range....
Chapter
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This chapter provides a synthesis of the geological history, chronology and magmatic evolution of Merapi. Stratigraphic field and geochronological data are used to divide Merapi into three main evolutionary stages and associated volcanic edifices (Proto-, Old and New Merapi) and eight broad volcano-stratigraphic units to characterise the eruptive a...
Chapter
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We draw on our experience in assisting with international crises through the volcano disaster assistance program (VDAP) and during the eruptions of Mount St. Helens in 1980–1986 and 2004–2008 to offer recommendations for successful observatory operations during times of crisis. The degree of success in responding to a crisis is profoundly affected...
Article
Purpose The purpose of this paper is to highlight the importance of a comprehensive global database on volcanic unrest (WOVOdat) as a resource to improve eruption forecasts, hazard evaluation and mitigation actions. Design/methodology/approach WOVOdat is a centralized database that hosts multi-parameter monitoring data sets from unrest and eruptio...
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Originally prepared for the United Nations Office for Disaster Risk Reduction, this is the first comprehensive assessment of global volcanic hazards and risk, presenting the state of the art in our understanding of global volcanic activity. It examines our assessment and management capabilities, and considers the preparedness of the global scientif...
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The 1963 AD eruption of Agung volcano was one of the most significant twentieth century eruptions in Indonesia, both in terms of its explosivity (volcanic explosivity index (VEI) of 4+) and its short-term climatic impact as a result of around 6.5 Mt SO2 emitted during the eruption. Because Agung has a significant potential to generate more sulphur-...
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There are ~750 active and potentially active volcanoes in Southeast Asia. Ash from eruptions of volcanic explosivity index 3 (VEI 3) and smaller pose mostly local hazards while eruptions of VEI ≥ 4 could disrupt trade, travel, and daily life in large parts of the region. We classify Southeast Asian volcanoes into five groups, using their morphology...
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抄録 ブルサン火山複合体(BVC)を構成するイロシンカルデラとブルサン火山は,フィリピン共和国のルソン島南東端に位置する。この論文は,小特集「フィリピン・ルソン島のイロシンカルデラとブルサン火山の地質と最近の噴火活動」(その1)と(その2)に掲載された論文について,その概要を述べたものである。Moriya(2014)は,フィリピン諸島の84火山の地形発達史を予察的にまとめており,フィリピンの火山の概要を理解することができる。Kobayashi et al. (2014a, b)は,カルデラ形成噴火の推移を明らかにしており,Kobayashi(2014)では,姶良カルデラと比較して両者の共通性を明確にしている。Danhara et al. (2014)は,イロシン火砕流および関連する堆積物の岩...
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Volcano Alert Levels (VALs) are used by volcanologists to quickly and simply inform local populations and government authorities of the level of volcanic unrest and eruption likelihood. Most VALs do not explicitly forecast volcanic activity but, in many instances they play an important role in informing decisions: defining exclusion zones and issui...
Chapter
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May 18, 1980. Sunrise and a crystal-clear morning. Mount St. Helens was a beautiful, peaceful, snow-capped mountain surrounded by pristine forests and lakes(Fig. 15.1). Yes, it was known to be spitting ash and shaking, but it was still fundamentally the same Mount St. Helens that had for decades been a favorite camping and fishing destination of lo...
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http://dx.doi.org/10.17014/ijog.vol1no4.20064Until now, the large eruption of Merapi in 1006 is believed to take place although the truth is still debatable. Previous investigation proposed that the ”pralaya” of the Ancient Mataram Kingdom in 928 Saka (1006) was due to a volcanic activity. Bemmelen also inferred that impact of the eruption had dest...
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The Irosin caldera located at the southeastern tip of Luzon Island in the Philippines was formed by the eruption of 41cal kBP Irosin ignimbrite. Bulusan, a post-caldera volcano, has repeated phreatic eruptions during historical times. The special issue on “Geology and Recent Eruptions of Irosin Caldera and Bulusan Volcano, Southern Luzon, Philippin...
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Bayesian event trees are now constructed before or during many volcanic crises, to reflect multiple possible scenarios and the relative and absolute likelihoods of each scenario. Group discussion followed by formal expert elicitation is an excellent way to estimate probabilities at each branch of a tree, but commonly neither sufficient time exists...
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Despite dense cloud cover, satellite-borne commercial Synthetic Aperture Radar (SAR) enabled frequent monitoring of Merapi volcano's 2010 eruption. Near-real-time interpretation of images derived from the amplitude of the SAR signals and timely delivery of these interpretations to those responsible for warnings, allowed satellite remote sensing for...
Article
In the last part of the 20th century and the beginning of the 21st century, Mt. Merapi in Central-Java Indonesia erupted about every 2-5 years. Most of the eruptions were low in explosivity, with VEI-3 or less. Eruptions usually involve the formation of a lava dome, either in the beginning or in the end of the eruptive episode. For the 2006 eruptio...
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A field reconnaissance study of the volcanic geology of Isarog volcano (Luzon, Philippines), complemented with radiocarbon dating, geochemical and petrological data, shows evidence for repeated explosive activity generating pyroclastic density currents and block-and-ash flows, including Holocene events. The chemical composition of juvenile material...
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Sound scientific management of volcanic crises is the primary tool to reduce significantly volcanic risk in the short-term. At present, a wide variety of qualitative or semi-quantitative strategies is adopted, and there is not yet a commonly accepted quantitative and general strategy. Pre-eruptive processes are extremely complicated, with many degr...
Article
The Irosin caldera, which is located in the province of Sorsogon, southern Luzon, Philippines, represents the largest extrusion of highly silicic magmas in the Bicol arc at ca. 41cal ka BP. The 41cal ka BP rhyolitic eruption led to a collapse and formation of the 11km–wide Irosin caldera. This paper presents the results of the stratigraphy, grain a...
Article
Before the 1991-1992 activity, a large andesite lava dome belonging to the penultimate Pinatubo eruptive period (Buag ∼ 500 BP) formed the volcano summit. Buag porphyritic andesite contains abundant amphibole-bearing microgranular enclaves of basaltic-andesite composition. Buag enclaves have lower K2O and incompatible trace element (LREE, U, Th) co...
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The largest known eruption of Mt. Pinatubo in the late Quaternary was the Inararo Tuff Formation (ITF) eruption, roughly estimated as five times larger than the 1991 eruption. The precise age of the ITF eruption has been uncertain. Here, a correlative of the ITF eruption, Layer D, is identified in marine sediments, and an age obtained. Tephras were...
Chapter
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Magmas feeding into the roots of active volcanoes contain dissolved gas. These magmas then exhibit a full range of degassing behavior, from purely passive (slow, between eruptions) to purely explosive (rapid, during explosive eruptions). Free, 'leaky' passive degassing reduces though does not completely eliminate explosive potential; 'tight' pluggi...
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The eruption of dacitic to rhyolitic pyroclastic flows, Irosin ignimbrite, resulted in the formation of the Irosin caldera in Bicol Peninsula, southern Luzon, Philippines. This paper presents the AMS (Accelerator Mass Spectrometry) ¹⁴C date of charcoal fragment from the Irosin ignimbrite that is distributed in the province of Sorsogon. The obtained...
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‘We have to understand volcano science to know what to monitor.” That simple statement by Antonius Ratdomopurbo, director of the Indonesian Center for Volcano Technology [Balai Penyelidikan dan Pengembangan‐Teknologi (BPPTK)],captured the spirit and content of a recent workshop about Merapi and Merapi‐type volcanoes. Merapi still is experiencing lo...
Conference Paper
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Proceedings summary of the genetic origins, physical characteristics and hazards of pyroclastic density currents from the 1814 to 2000 eruption of Mayon Volcano, Philippines
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1] We describe an event tree scheme to quantitatively estimate both long-and short-term volcanic hazard. The procedure is based on a Bayesian approach that produces a probability estimation of any possible event in which we are interested and can make use of all available information including theoretical models, historical and geological data, and...
Article
Mayon is the most active volcano along the east margin of southern Luzon, Philippines. Petrographic and major element data indicate that Mayon has produced a basaltic to andesitic lava series by fractional crystallization and magma mixing. Trace element data indicate that the parental basalts came from a heterogeneous mantle source. The unmodified...
Article
We are creating a pilot database (WOVOdat - the World Organization of Volcano Observatories database) using an open source database and content generation software, allowing web access to data of worldwide volcanic seismicity, ground deformation, fumarolic activity, and other changes within or adjacent to a volcanic system. After three years of dis...
Article
Groundwater level changes associated with eruptions have been observed at Mayon Volcano, Philippines and Usu and Miyake-jima Volcanoes, Japan. Possible mechanisms include strain, uplift or subsidence of the ground surface, boiling away of recharge and changes in the permeability of the aquifer. These mechanisms may work alone or in combination. In...
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WOVOdat (World Organization of Volcano Observatories database of volcanic unrest) will for the first time bring together data of worldwide volcanic seismicity, ground deformation, fumarolic activity, and other changes within or adjacent to a volcanic system. Although a large body of data and experience has been built over the past century, currentl...
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New measurements, statistical analyses, and models support the conjecture that a large earthquake can trigger subsequent volcanic eruptions over surprisingly long distance and time scales.
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The 1991 eruption of Mount Pinatubo generated extreme sediment yields from watersheds heavily impacted by pyroclastic flows. Bedload sampling in the Pasig–Potrero River, one of the most heavily impacted rivers, revealed negligible critical shear stress and very high transport rates that reflected an essentially unlimited sediment supply and the enh...
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The eruption of Mount Pinatubo on 15 June 1991 was the second largest volcanic eruption of the 20th century. In their Perspective, Newhall et al. discuss the geologic lessons learned from Pinatubo. In an accompanying Perspective, Robock addresses the climatic impacts of the eruption.
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Event trees are useful frameworks for discussing probabilities of possible outcomes of volcanic unrest. Each branch of the tree leads from a necessary prior event to a more specific outcome, e.g., from an eruption to a pyroclastic flow. Where volcanic processes are poorly understood, probability estimates might be purely empirical - utilizing obser...
Conference Paper
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DOST-PHIVOLCS' 2001 early-warning efforts, assessment, mitigation strategy and evaluated outcomes of impending breakout of the Pinatubo Caldera Lake.
Article
A geochemical investigation of Mount Pinatubo's volcanic lake indicates mixing between neutral chloride spring discharge from springs in the crater walls and meteoric waters from precipitation and runoff. I originally hypothesized that the lake water is a mixture of deep hydrothermal acid sulfate fluid representative of magmatic input into the hydr...
Article
The 1991-92 eruption of Pinatubo Volcano, Philippines was a signal event in the annals of volcanology. For the first time, modern monitoring captured the pre-, syn-, and post-eruption signatures of a sulfur-rich, plinian, caldera-forming eruption. Approximately 5 km3 of magma was erupted, of which slightly more than half became pyroclastic flows, a...
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Stratigraphy and radiocarbon dating of pyroclastic deposits at Merapi Volcano, Central Java, reveals ∼10,000 years of explosive eruptions. Highlights include:(1) Construction of an Old Merapi stratovolcano to the height of the present cone or slightly higher. Our oldest age for an explosive eruption is 9630±60 14C y B.P.; construction of Old Merapi...
Article
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20 years ago, a major volcanic eruption propelled Mt. St. Helens, Washington State, onto the international stage. In this Perspective, Newhall explains how the study of explosive volcanism has changed in the aftermath of Mt. St. Helens. Many lessons have been learned through close interdisciplinary and international collaboration, and forecasts are...
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Lahar hazard at Pinatubo is a function of prodigious sediment yield from Pinatubo's upper and middle slopes and the sediment storage capacity in the adjoining lowlands. Both are diminishing but at mismatched rates. Sediment yields set world records during the first three posteruption years, and yields in the Balin Baquero-Bucao and Marella watershe...
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Historical eruptions have produced lahars and floods by perturbing snow and ice at more than 40 volcanoes worldwide. Most of these volcanoes are located at latitudes higher than 35; those at lower latitudes reach altitudes generally above 4000 m. Volcanic events can perturb mantles of snow and ice in at least five ways: (1) scouring and melting by...
Chapter
Historical seismicity, ground deformation, thermal activity, and eruptions at large Quaternary calderas of the world are common, spatially and temporally complex, and usually caused by combinations of tectonic, magmatic, and hydrologic processes. Study of historical unrest helps to define what is ordinary and what is extraordinary, and to document...
Chapter
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Historical seismicity, ground deformation, thermal activity, and eruptions at large Quaternary calderas of the world are common, spatially and temporally complex, and usually caused by combinations of tectonic, magmatic, and hydrologic processes. Study of historical unrest helps to define what is ordinary and what is extraordinary, and to document...
Article
Geologic studies in the Lake Atitlán region, Guatemala, have revealed three cycles of stratovolcano growth, major silicic eruptions, and caldera formation. The first cycle (14-11 Ma) culminated in a series of five Maria Tecun ash-flow eruptions and formation of the large Atitlán I caldera centered just north of the present Lake Atitlán basin. The s...
Article
Lake Atitlán, a caldera lake in western Guatemala, was investigated for evidence of recent volcanic and tectonic activity. No vents, faults, or folds are apparent on high-resolution seismic reflection profiles of lake sediment, representing at least 17,500 years and probably more than 35,000 years of deposition. Three post-caldera stratovolcanoes (...
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Atitlán caldera has been the site of several silicic eruptions within the last 150,000 years, following a period of basalt/andesite volcanism. The silicic volcanism began with 5–10 km3 of rhyodacites, erupted as plinian fall and pyroclastic flows, about 126,000 yr. B.P. At 85,000 yr. B.P. 270–280 km3 of compositionally distinct rhyolite was erupted...
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Volcanoes erupt magma (molten rock containing variable amounts of solid crystals, dissolved volatiles, and gas bubbles) along with pulverized pre-existing rock (ripped from the walls of the vent and conduit). The resulting volcanic rocks vary in their physical and chemical characteristics, e.g., degree of fragmentation, sizes and shapes of fragment...
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A large debris avalanche in 1628(1) A.D. carried away the southeast side of Mount lriga, a youn~ stratovolcano in the Philippines. The resulting deposit covers about 70 Ian , and has a volume of more than I.S lan J. A 4 x 5 km lake formed behind and eventuany overtopped the deposit without catastrophically breaching its dam. Failure of the side of...
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Public statements about volcanic activity at Mount St. Helens include factual statements, forecasts, and predictions. A factual statement describes current conditions but does not anticipate future events. A forecast is a comparatively imprecise statement of the time, place, and nature of expected activity. A prediction is a comparatively precise s...
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Geologic and geophysical data from Laguna de Ayarza, a figure-8-shaped doublecaldera lake in the Guatemalan highlands, show no evidence of postcaldera eruptive tectonic activity. The bathymetry of the lake has evolved as a result of sedimentary infilling. The western caldera is steep-sided and contains a large flat-floored central basin 240 m deep....
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A debris-avalanche deposit extends 43 km northwestward from the base of Mount Shasta across the floor of Shasta Valley, California, where it covers an area of at least 450 km 2 • The surface of the deposit is dotted with hundreds of mounds, hills, and ridges, all formed of blocks of pyroxene andesite and unconsolidated volcaniclastic deposits deriv...
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Thirteen eruptions of Mount St. Helens between June 1980 and December 1982 were predicted tens of minutes to, more generally, a few hours in advance. The last seven of these eruptions, starting with that of mid-April 1981, were predicted between 3 days and 3 weeks in advance. Precursory seismicity, deformation of the crater floor and the lava dome,...
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Domes offer unique opportunities to measure or infer the characteristics of magmas that, at domes and elsewhere, control explosive activity. A review of explosive activity associated with historical dome growth shows that: 1.(1) explosive activity has occurred in close association with nearly all historical dome growth;2.(2) whole-rock SiO2 content...
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Knowledge of the frequencies of highly explosive, moderately explosive, and nonexplosive eruptions would be useful in a variety of volcano studies. Historical records are generally incomplete, however, and contain very little quantitative data from which explosive magnitude can be estimated. Only the largest eruptions have a complete record back to...
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A composite estimate of the magnitude of past explosive eruptions, termed the volcanic Explosivity Index (VEI), is proposed as a semiquantitative compromise between poor data and the need in various disciplines to evaluate the record of past volcanism. The VEI has been assigned to over 8000 historic and prehistoric eruptions, and a complete list is...
Article
The largest known eruption of Mt. Pinatubo in the late Quaternary was the Inararo Tuff Formation (ITF) eruption, roughly estimated as five times larger than the 1991 eruption. The precise age of the ITF eruption has been uncertain. Here, a correlative of the ITF eruption, Layer D, is identified in marine sediments, and an age obtained. Tephras were...
Article
Full-text available
Illustrations on folded sheets in pocket. Thesis (Ph. D.)--Dartmouth College, 1980. Includes bibliographical references (leaves 337-353).

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