Daniel O'Hara

• Doctor of Philosophy
• PostDoc Position at GFZ Helmholtz Centre for Geosciences

Composite volcanoes are dynamic landforms that require comprehensive morphological analysis to understand their formation, degradation and associated controlling processes. Establishing Digital Elevation Model (DEM) source, spatial resolution and edifice delineation method are the first essential steps to quantify volcano morphometry. The delineati...

The erosional state of a landscape is often assessed through a series of metrics that quantify the morphology of drainage basins and divides. Such metrics have been well explored in tectonically active environments to evaluate the role of different processes in sculpting topography, yet relatively few works have applied these analyses to radial lan...

Oceanic island volcanoes are a source of multiple hazards, including hazards related to the instability of volcanic edifices and flanks. Collapse events as a result of flank instability are potentially tsunamigenic with devastating impacts, especially in the near field. An example of an unstable volcano with a history of tsunamigenic collapses is F...

The erosional state of a landscape is often assessed through a series of metrics that quantify the morphology of drainage basins and divides. Such metrics have been well-explored in tectonically-active environments to evaluate the role of different processes in sculpting topography, yet relatively few works have applied these analyses to radial lan...

The morphology and distribution of volcanic edifices in volcanic terrains encodes the structure and evolution of underlying magma transport as well as surface processes that shape landforms. How magmatic construction and erosion interact on long timescales to sculpt these landscapes, however, remains poorly resolved. In the Cascades arc, distribute...

Session: From shape to process: geomorphology as a tool to unravel volcanic processes Abstract: Composite volcanoes have diverse morphologies due to their inextricably intertwined eruption, intrusion, and degradation histories. Surface runoff, a major erosional process involved in volcanic degradation, is dominantly controlled by both climatic, l...

Abstract: Composite volcanoes have diverse morphologies due to their inextricably intertwined eruption, intrusion, and degradation histories. Surface runoff, a major erosional process involved in volcanic degradation, is dominantly controlled by both climatic, lithologic, and topographic factors. Analogue models offer the opportunity to examine rai...

Like many other lakes in the world, the interconnected Abaya and Chamo lakes in the Southern Main Ethiopian Rift are affected by rapid sediment accumulation. Although land degradation is a well-known issue in this part of the African continent, the main sediment sources, their spatial distribution and interaction in the Abaya–Chamo lakes’ basin hav...

Like many other lakes in the world, the interconnected Abaya and Chamo lakes in the Southern Main Ethiopian Rift are affected by rapid sediment accumulation. Although land degradation is a well-known issue in this part of the African continent, the main sediment sources, their spatial distribution and interaction in the Abaya–Chamo lakes’ basin hav...

The long-term (ka to ma) degradation of a volcanic edifice is controlled by both regional (e.g., climate, tectonics) and local factors (e.g., original morphology, lithology), resulting in both long-lasting weathering and river incision and short-term hazardous events, such as flank collapses and lahars. Trends among the morphometry of stratovolcano...

Volcano morphology is the result of complex interactions between constructive and destructive phases. The dynamics of eruptive, intrusive and erosive processes are reflected in the shapes of volcanoes today. Quantifying the morphology and degradation patterns of composite volcanoes can provide new insights into the evolution of these landforms and...

Transcrustal magma transport systems reflect accumulation of small-volume intrusions over long timescales, transiently altering the thermal, mechanical, and compositional states of the crust. The long-term impact of such repeated and spatially-distributed intrusive magmatism on surface topography remains relatively unexplored. Here, we investigate...

Volcanoes are extremely dynamic landforms. They grow by the accumulation of eruptive products and intrusions and degrade by a range of erosion processes such as superficial runoff, chemical and physical weathering, fluvial and glacial incision, and mass movements. In this study, we aim at documenting and quantifying the morphology of natural compos...

Plain Language Summary Magma reservoirs are commonly assumed to be located directly beneath their associated volcanic edifices. This “central reservoir” paradigm dominates volcano modeling and monitoring. However, the actual spatial relations between volcanoes and underlying magma reservoirs are poorly known. We compile a database of geophysical st...

Increased resolution of data constraining topography and crustal structures provides new quantitative ways to assess province-scale surface-subsurface connections beneath volcanoes. We used a database of mapped vents to extract edifices with known epoch ages from digital elevation models (DEMs) in the Cascades arc (western North America), deriving...

A primary goal of geomorphology is to infer from topographic form the processes that drive landscape evolution. Often implicit is the assumption that orogen-scale ( m^2 planform area) transient landscape changes on Earth are driven by equally large-scale transient tectonics, climate, or sea level. Here we argue that meso-scale (10^5–10^10 m^2) upli...

Topography of the Cascades Arc encodes a complex history of volcanism, tectonics, and erosion. Edifices range from cinder cones to calderas, stratovolcanoes, and compound volcanic complexes. Often, these features are spatially localized around magmatic centers, alluding to the underlying magma transport network. A new USGS database compiles the loc...

Magmatism is an important driver of landscape adjustment over ∼10% of Earth's land surface, producing 10³- to 10⁶-km² terrains that often persistently resurface with magma for 1–10 s of Myr. Construction of topography by magmatic intrusions and eruptions approaches or exceeds tectonic uplift rates in these settings, defining regimes of landscape ev...

In subduction zone backarcs extensional deformation and arc volcanism interact and these processes, together with mass wasting, shape the seafloor morphology. We present a new bathymetric map of the Santorini-Christiana-Amorgos backarc region of the Hellenic subduction zone by merging high-resolution multibeam swath data from the R/V Langseth PROTE...

Tectonic slivers have profound implications on the mechanical behavior of forearcs and subduction zones. Southern Taiwan is characterized by pre-collision forearc slivering that likely exerts important controls on the evolution of collision. Inversion of focal mechanism solutions for seismogenic strain reveals spatially partitioned plate motion sou...

Taiwan is the product of modern subduction polarity reversal coupled with arc-continent collision. The NW-moving Philippine Sea plate (PSP) subducts beneath the Eurasian plate (EUR) to the northeast of Taiwan at the Ryukyu trench, while overriding EUR south of Taiwan at the Manila trench, bringing the Luzon volcanic arc into collision with the defo...

Earthquakes in the upper plate offshore SE Taiwan provide insight into the crustal assembly of the eastern Taiwan arc-continent collision. We invert groups of focal mechanisms for best-fitting strain tensors and show that eastern Taiwan likely records a pre-collision history of partitioned deformation overprinted by collision-driven plate-motion pa...

Slip vectors of preferred nodal planes derived using a Gaussian model for inverting focal mechanisms for strain provide constraints on probable fault geometries and fault block kinematics. We use preferred nodal plane slip vectors for shallow earthquakes in the Luzon forearc basin of southeast Taiwan to understand the relative orientations of block...

The Huatung Ridge is a north-trending bathymetric high situated between the Luzon Arc and the Southern Longitudinal Trough off the coast of SE Taiwan. Strain inversions for shallow (