Frank I. Gonzalez

A comparison of coincidental time series of the ocean surface height by satellite altimeter, mooring, and inverted echo sounder

Altimetric measurements of sea surface height at two locations in the western tropical Pacific Ocean are compared to estimates of the dynamic sea surface height computed from cotemporal surface-to-bottom temperature/salinity measurements on moorings and acoustic travel time measured by bottom-moored inverted echo sounders. The results show statistically high correlation between the in situ measurements at periods greater than 5 days and between the altimeter and in situ measurements at periods greater than 20 days. The rms difference between any two modes of observation is consistently between 2 and 3 cm.

Generating Random Earthquake Events for Probabilistic Tsunami Hazard Assessment

To perform probabilistic tsunami hazard assessment for subduction zone earthquakes, it is necessary to start with a catalog of possible future events along with the annual probability of occurrence, or a probability distribution of such events that can be easily sampled. For near-field events, the distribution of slip on the fault can have a significant effect on the resulting tsunami. We present an approach to defining a probability distribution based on subdividing the fault geometry into many subfaults and prescribing a desired covariance matrix relating slip on one subfault to slip on any other subfault. The eigenvalues and eigenvectors of this matrix are then used to define a Karhunen-Loève expansion for random slip patterns. This is similar to a spectral representation of random slip based on Fourier series but conforms to a general fault geometry. We show that only a few terms in this series are needed to represent the features of the slip distribution that are most important in tsunami generation, first with a simple one-dimensional example where slip varies only in the down-dip direction and then on a portion of the Cascadia Subduction Zone.

The Pattern Method for incorporating tidal uncertainty into probabilistic tsunami hazard assessment (PTHA)

In this paper, we describe a general framework for incorporating tidal uncertainty into probabilistic tsunami hazard assessment and propose the Pattern Method and a simpler special case called the

Designing an offshore geophysical network in the Pacific Northwest for earthquake and tsunami early warning and hazard research

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Nonlinear features of internal waves off Baja California as observed from the SEASAT imaging radar

Δt Method as effective approaches. The general framework also covers the method developed by Mofjeld et al. (J Atmos Ocean Technol 24(1):117–123, 2007) that was used for the 2009 Seaside, Oregon probabilistic study by González et al. (J Geophys Res 114(C11):023, 2009). We show that the Pattern Method is superior to past approaches because it takes advantage of our ability to run the tsunami simulation at multiple tide stages and uses the time history of flow depth at strategic gauge locations to infer the temporal pattern of waves that is unique to each tsunami source. Combining these patterns with knowledge of the tide cycle at a particular location improves the ability to estimate the probability that a wave will arrive at a time when the tidal stage is sufficiently large that a quantity of interest such as the maximum flow depth exceeds a specified level. Python scripts to accompany this paper are available at DOI 10.5281/zenodo.12406.

Heterogeneities in regional volumes of distribution and flows in rabbit heart

Applying probabilistic methods to infrequent but devastating natural events is intrinsically challenging. For tsunami analyses, a suite of geophysical assessments should be in principle evaluated because of the different causes generating tsunamis (earthquakes, landslides, volcanic activity, meteorological events, and asteroid impacts) with varying mean recurrence rates. Probabilistic Tsunami Hazard Analyses (PTHAs) are conducted in different areas of the world at global, regional, and local scales with the aim of understanding tsunami hazard to inform tsunami risk reduction activities. PTHAs enhance knowledge of the potential tsunamigenic threat by estimating the probability of exceeding specific levels of tsunami intensity metrics (e.g., run-up or maximum inundation heights) within a certain period of time (exposure time) at given locations (target sites); these estimates can be summarized in hazard maps or hazard curves. This discussion presents a broad overview of PTHA, including (i) sources and mechanisms of tsunami generation, emphasizing the variety and complexity of the tsunami sources and their generation mechanisms, (ii) developments in modeling the propagation and impact of tsunami waves, and (iii) statistical procedures for tsunami hazard estimates that include the associated epistemic and aleatoric uncertainties. Key elements in understanding the potential tsunami hazard are discussed, in light of the rapid development of PTHA methods during the last decade and the globally distributed applications, including the importance of considering multiple sources, their relative intensities, probabilities of occurrence, and uncertainties in an integrated and consistent probabilistic framework.

Open‐ocean validation of TOPEX/POSEIDON sea level in the western equatorial Pacific

Every few hundred years, the Cascadia subduction zone off the coast of the Pacific Northwest hosts devastating earthquakes, and there is a growing awareness of the need to be prepared for these events. An offshore cabled observatory extending the length of the Cascadia subduction zone would enhance the performance of the earthquake and tsunami early warning systems, would enable real time monitoring and predictions of the incoming tsunami, and would contribute substantially to scientific research aimed at mitigating the hazard. The University of Washington has recently initiated a study to develop a conceptual design for the U.S. portion of an offshore observatory for earthquake and tsunami early warning and research. This paper presents the motivation for this work and plans for the study.