Publications

The rivers of western Oregon have diverse forms and characteristics, with channel substrates ranging from continuous alluvial gravel to bare bedrock. Analysis of several measurable morphologic attributes of 24 valley reaches on 17 rivers provides a basis for comparing nonalluvial and alluvial channels. Key differences are that alluvial reaches have greater bar area, greater migration...

In September 2004, Mount St. Helens volcano erupted after nearly 18 years of quiescence. However, it is unclear from the limited geophysical observations when or if the magma chamber replenished following the 1980–1986 eruptions in the years before the 2004–2008 extrusive eruption. We use coda wave interferometry with repeating earthquakes to measure small changes in the velocity...

The 40Ar/39Ar investigations of a large suite of fine-grained basaltic rocks of the Boring volcanic field (BVF), Oregon and Washington (USA), yielded two primary results. (1) Using age control from paleomagnetic polarity, stratigraphy, and available plateau ages, 40Ar/39Ar recoil model ages are defined that provide reliable age results in the absence of an age plateau, even in cases of...

The characteristics of magma supply, storage, and transport are among the most critical parameters governing volcanic activity, yet they remain largely unconstrained because all three processes are hidden beneath the surface. Hawaiian volcanoes, particularly Kīlauea and Mauna Loa, offer excellent prospects for studying subsurface magmatic processes, owing to their accessibility and...

The Hawaiian Volcano Observatory (HVO) was established as a natural laboratory to study volcanic processes. Since the most frequent form of volcanic activity in Hawai‘i is effusive, a major contribution of the past century of research at HVO has been to describe and quantify lava flow emplacement processes. Lava flow research has taken many forms; first and foremost it has been a...

The 19 known shield volcanoes of the main Hawaiian Islands—15 now emergent, 3 submerged, and 1 newly born and still submarine—lie at the southeast end of a long-lived hot spot chain. As the Pacific Plate of the Earth’s lithosphere moves slowly northwestward over the Hawaiian hot spot, volcanoes are successively born above it, evolve as they drift away from it, and eventually die and...

Hawaiian volcanoes build long rift zones and some of the largest volcanic edifices on Earth. For the active volcanoes on the Island of Hawai‘i, the growth of these rift zones is upward and seaward and occurs through a repetitive process of decades-long buildup of a magma-system head along the rift zones, followed by rapid large-scale displacement of the seaward flank in seconds to...

An anomalous body with low Vp (compressional wave velocity), low Vs (shear wave velocity), and high Vp/Vs anomalies is observed at 8–11 km depth beneath the upper east rift zone of Kilauea volcano in Hawaii by simultaneous inversion of seismic velocity structure and earthquake locations. We interpret this body to be a crustal magma reservoir beneath the volcanic pile, similar to those...

This chapter, prepared in celebration of the Hawaiian Volcano Observatoryʼs centennial, provides a historical lens through which to view modern paradigms of Hawaiian-style eruption dynamics. The models presented here draw heavily from observations, monitoring, and experiments conducted on Kīlauea Volcano, which, as the site of frequent and accessible eruptions, has attracted scientists...

Mammoth Mountain, California, is a dacitic volcano that has experienced several periods of unrest since 1989. The onset of diffuse soil CO2 emissions at numerous locations on the flanks of the volcano began in 1989–1990 following an 11-month period of heightened seismicity. CO2 emission rates were measured yearly from 1995 to 2013 at Horseshoe Lake (HSL), the largest tree kill area on...

A gigantic ∼12 km3 landslide detached from the west wall of Lake Tahoe (California-Nevada, USA), and slid 15 km east across the lake. The splash, or tsunami, from this landslide eroded Tioga-age moraines dated as 21 ka. Lake-bottom short piston cores recovered sediment as old as 12 ka that did not reach landslide deposits, thereby constraining the landslide age as 21–12 ka. Movement of...

The first volcanic gas studies in Hawai‘i, beginning in 1912, established that volatile emissions from Kīlauea Volcano contained mostly water vapor, in addition to carbon dioxide and sulfur dioxide. This straightforward discovery overturned a popular volatile theory of the day and, in the same action, helped affirm Thomas A. Jaggar, Jr.’s, vision of the Hawaiian Volcano Observatory (HVO)...