About
105
Publications
19,654
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
2,218
Citations
Introduction
Publications
Publications (105)
Dynamic stresses on the order of ~1 kPa from passing waves of mainshock earthquakes can trigger aftershocks at remote distances. Here, we investigate the prevalence of remote earthquake triggering in northern Chile, where aseismic-slip triggering has been documented. Our twofold approach to quantify triggerability includes a statistical difference-...
Scientists are making progress on illuminating how undersea sedimentary deposits called turbidites form and on reconstructing the complex histories they record. But it’s not an easy task.
We investigate the effects of site response on source parameters using earthquakes recorded by a dense nodal array in Oklahoma. While it is well-known that near-surface unconsolidated sediments can cause an apparent breakdown of earthquake self-similarity, the influence of laterally varying site conditions remains unclear. We analyze site condition...
We test the behavior of the United States (US) West Coast ShakeAlert earthquake early warning (EEW) system during temporally close earthquake pairs to understand current performance and limitations. We consider performance metrics based on source parameter and ground-motion forecast accuracy, as well as on alerting timeliness. We generate ground-mo...
We examine the real-time earthquake detection and alerting behavior of the Propagation of Local Undamped Motion (PLUM) earthquake early warning (EEW) algorithm and compare PLUM’s performance with the real-time performance of the current source-characterization-based ShakeAlert System. In the United States (U.S.), PLUM uses a two-station approach to...
There is a little seismologist in everyone. One secret to unlocking a student’s science potential at the undergraduate level is to offer laboratory exercises that leverage the inspiration, team spirit, and creativity already present in the current generation of incoming college students. In this lab exercise we do that by using smartphones to cause...
We determine an optimal alerting configuration for the propagation of local undamped motion (PLUM) earthquake early warning (EEW) algorithm for use by the U.S. ShakeAlert system covering California, Oregon, and Washington. All EEW systems should balance the primary goal of providing timely alerts for impactful or potentially damaging shaking while...
The PLUM (Propagation of Local Undamped Motion) earthquake early warning (EEW) algorithm differs from typical source‐based EEW algorithms as it predicts shaking directly from observed shaking without first deriving earthquake source information (e.g., magnitude and epicenter). Here, we determine optimal PLUM event detection thresholds for U.S. West...
We examine the cyclic amplitude variation of seismic noise recorded by continuous three-component broadband seismic data with durations spanning 91 to 713 days (2008–2011) from three different networks: Anza seismic network, IDA network and the Transportable seismic array. These stations surround the San Jacinto Fault Zone (SJFZ) in southern Califo...
Defining the nature of faulting, the stress needed to trigger earthquakes, and the stress state of faults remains fundamental to understanding the earthquake cycle. Studying remote dynamic triggering allows us to probe faults to systemically address the fundamental physical mechanisms of faulting. Using 13 years of data (2004–2016) from the EarthSc...
We explore the detectability of M2 tidal tilt in the western part of the United States, using seismic velocity data from 40 stations in the EarthScope Transportable Array (TA) network. We augment these data with data from two additional stations both collocated at the Piñon Flats Observatory (PFO) in southern California (networks TA and Incorporate...
Understanding and modeling variability of ground motion is essential for building accurate and precise ground motion prediction equations, which can net site‐specific characterization and reduced hazard levels. Here, we explore the spatial variability in peak ground velocity (PGV) at Sage Brush Flats along the San Jacinto Fault in Southern Californ...
We evaluate the timeliness and accuracy of ground-motion-based earthquake early warning (EEW) during the July 2019 M 6.4 and 7.1 Ridgecrest earthquakes. In 2018, we began retrospective and internal real-time testing of the propagation of local undamped motion (PLUM) method for earthquake warning in California, Oregon, and Washington, with the poten...
Remote earthquake triggering is a well-established phenomenon. Triggering is commonly identified from statistically significant increases in earthquake rate coincident with the passage of seismic energy. In establishing rate changes, short duration earthquake catalogs are commonly used, and triggered sequences are not typically analyzed within the...
We test the Japanese ground‐motion‐based earthquake early warning (EEW) algorithm, propagation of local undamped motion (PLUM), in southern California with application to the U.S. ShakeAlert system. In late 2018, ShakeAlert began limited public alerting in Los Angeles to areas of expected modified Mercalli intensity (I_(MMI)) 4.0+ for magnitude 5...
To improve models of ground motion estimation and probabilistic seismic hazard analyses, the engineering seismology field is moving toward developing fully nonergodic ground motion models, models specific for individual source‐to‐site paths. Previous work on this topic has examined systematic variations in ground‐motion along particular paths (from...
Seasonal lake Gornersee forms at the confluence of Gornergletscher and Grenzgletscher, Switzerland, and experiences outburst floods annually in midsummer. To study the interplay between lake drainage, glacier movement and crevasse activity, high-frequency seismometers and GPS receivers were deployed in networks near Gornersee during the summer abla...
Ground-motion prediction equations (GMPEs) are critical elements of probabilistic seismic hazard analysis (PSHA), as well as for other applications of ground motions. To isolate the path component for the purpose of building nonergodic GMPEs, we compute a regional GMPE using a large dataset of peak ground accelerations (PGAs) from small-magnitude e...
Today's technology is opening up new ways to learn. Here, we introduce Tilt Trivia, a suite of quiz-style, multiplayer games for use on mobile devices and tablets (Android or Apple) to help students learn simple definitions and facts. This mobile device game was built using the Unity engine and has a multiplayer functionality that runs seamlessly,...
We develop a frequency-domain array-based detection algorithm that exploits the gridded station configuration (interstation spacing of 70 km) of the EarthScopeTransportable Array to detect and locate small magnitude (M < 2:5) earthquakes.Our method uses the geographic extent of frequency-amplitude time-series data to determine epicentral locations...
Technological advances in combination with the onslaught of data availability allow for large seismic data streams to automatically and systematically be recorded, processed, and stored. Here, we develop an automated approach to identify small, local earthquakes within these large continuous seismic data records. Our aim is to automate the process...
High-melt areas of glaciers and ice sheets foster a rich spectrum of ambient seismicity. These signals not only shed light on source mechanisms (e.g. englacial fracturing, water flow, iceberg detachment, basal motion) but also carry information about seismic wave propagation within glacier ice. Here, we present two approaches to measure and potenti...
To better understand earthquake source processes involved in dynamically triggering remote aftershocks, we use data from the EarthScope Transportable Array (TA) that provide uniform station sampling, similar recording capabilities, large spatial coverage, and in many cases, repeat sampling at each site. To avoid spurious detections, which are an in...
Mountain glaciers represent one of the largest repositories of fresh water in alpine regions globally. However, little is known about the processes by which water moves through these systems. Analysis of data from a deployment of seismometers located near an ice marginal lake in the Swiss Alps reveals, for the first time, that harmonic tremor occur...
We test the feasibility of rapidly detecting and characterizing earthquakes with the Quake-Catcher Network (QCN) that connects low-cost microelectromechanical systems accelerometers to a network of volunteer-owned, Internet-connected computers. Following the 3 September 2010 M 7.2 Darfield, New Zealand, earthquake we installed over 180 QCN sensors...
WATER-RELATED SEISMIC SOURCES IN GLACIERS AND ICE SHEETS
Fabian Walter1,2, David Heeszel3, Debi Kilb3, Claudia Röösli4, Philippe Roux2, Pierre Dalban Canassy1, Stephan Husen4, Edi Kissling5, Martin P. Lüthi1, Martin Funk1, John F. Clinton4 and Helen Amanda Fricker3.
1Versuchsanstalt für Wasserbau, Hydrologie und Glaziologie (VAW), ETH Zürich, 809...
Online material: Sample SeisSound video products; MATLAB computer codes; sample data set.
The increased popularity of YouTube videos has changed the format of how information is distributed and assimilated, highlighting the importance of including auditory information in videos. Videos that include sound also permeate the research community, as ev...
Kappa is a one-parameter estimator of the spectral amplitude decay with frequency of a seismogram. Low values (∼5 ms) indicate limited attenuation of high-frequency energy whereas higher values (∼40 ms) indicate high-frequency energy has been removed. Kappa is often assumed to be a site term and used in seismic designs. We address two key questions...
Advances are continually made in our understanding of the physics
governing earthquake triggering, yet many questions remain. Here, we
investigate if there exists a minimum dynamic stress threshold (i.e., in
amplitude, frequency or both) required to trigger remote earthquakes
using data collected by >400 stations in EarthScope's USArray
Transportab...
To constrain an earthquake's source properties, the path- and site-effect contributions to the seismic waveform can be approximated using another earthquake as an empirical Green's function (EGF). An ideal EGF earthquake is smaller in magnitude than the mainshock and shares a similar focal mechanism and hypocenter. Here, we quantify how to optimall...
The Kinect technology allows for hands-free game play, greatly
increasing the accessibility of gaming for those uncomfortable using
controllers. How it works is the Kinect camera transmits invisible
near-infrared light and measures its "time of flight" to reflect off an
object, allowing it to distinguish objects within 1 centimeter in depth
and 3 m...
Data from dense seismic arrays can be used to visualize the propagation
of seismic waves, resulting in animations effective for teaching both
general and advanced audiences. One of the first visualizations of this
type was developed using Objective C code and EarthScope/USArray data,
which was then modified and ported to the Matlab platform and has...
It is important for seismologists to effectively convey information
about catastrophic earthquakes, such as the magnitude 9.0 earthquake in
Tohoku-Oki, Japan, to general audience who may not necessarily be
well-versed in the language of earthquake seismology. Given recent
technological advances, previous approaches of using "snapshot" static
images...
The National Science Foundation's Ocean Observatories Initiative (OOI)
is constructing observational and computer infrastructure that will
provide sustained ocean measurements to study climate variability, ocean
circulation, ecosystem dynamics, air-sea exchange, seafloor processes,
and plate-scale geodynamics over the next ~25-30 years. To accompli...
The southern San Andreas fault has not experienced a large earthquake for approximately 300 years, yet the previous five earthquakes occurred at ~180-year intervals. Large strike-slip faults are often segmented by lateral stepover zones. Movement on smaller faults within a stepover zone could perturb the main fault segments and potentially trigger...
Current technologies offer the opportunity for ocean science to expand its traditional expeditionary base by embracing e-science methods of continuous interactive real-time research. The Ocean Observatories Initiative Cyberinfrastructure (OOI CI) is an NSF-funded effort to develop a national cyberinfrastructure that will allow researchers, educator...
Sonification of seismic data is an innovative way to represent seismic data in the audible range (Simpson, 2005). Seismic waves with different frequency and temporal characteristics, such as those from teleseismic earthquakes, deep ``non-volcanic'' tremor and local earthquakes, can be easily discriminated when time-compressed to the audio range. He...
The San Jacinto Fault Zone (SJFZ) in southern California features a complex distribution of fault traces and seismic sources. Earthquakes in this region rarely occur along a linear, well-defined fault trace and instead tend to occupy a volume of the crust. The ANZA seismic network has been operational in this area since 1982, and currently over 30,...
Using high-density seismometer arrays we examine the temporal and spatial signature of icequake activity on Gornergletscher, Switzerland, during drainages of a nearby glacier-dammed lake in the summer months in 2004, 2006 and 2007. Our seismometer arrays had apertures of approximately 300-400m and consisted of 8-24 3-component seismometers installe...
We perform a systematic survey of dynamically triggered earthquakes in the Salton Sea region of southern California using borehole seismic data recordings (2007 to present). We define triggered events as high-frequency seismic energy during large-amplitude seismic waves of distant earthquakes. Our mainshock database includes 26 teleseismic events (...
In consecutive years, a fifth grade teacher of a self-contained classroom enacted five-week Earth sciences units that included learning activities focusing on the interpretation of seismograms and the location of earthquake epicenters. In one class, the unit utilized an embedded design that situated learners within the spatial and temporal extent o...
The Salton Sea region in southern California provides an ideal location to study the relationship between transcurrent and extensional motion in the northern Gulf of California margin, allowing us to investigate the spatial and temporal interaction of faults in the area and better understand their kinematics. In this region, the San Andreas Fault (...
The scalable RoomQuake seismology project uses a learning technology framework-embedded phenomena (Moher, 2006)---that simulates seismic phenomena mapped directly onto the physical space of classrooms. This project, aimed at the upper elementary level, situates students as the scientists engaged in an extended investigation designed to discover the...
It has been traditionally held that aftershocks occur within one to two fault lengths of the mainshock. Here we demonstrate that this perception has been shaped by the sensitivity of seismic networks. The 31 October 2001 Mw 5.0 and 12 June 2005 Mw 5.2 Anza mainshocks in southern California occurred in the middle of the densely instrumented ANZA sei...
Previously, the methods used by scientists to locate an earthquake epicenter were so cumbersome, even for scientists, that the epicenter location methodology needed to be simplified before it was presented to K-12 students. Today, because of the advances in computer technology, there is a smaller divide between what is performed in research laborat...
The CyberTEAM project engages Computer Science (CS) students in the creation of Web-based applications as learning resources for middle school classrooms. The Flash-based Earthquake Location Tool (FELT) is one of such learning resources. Implemented in ActionScript 3.0, FELT allows its client to run on Flash Player and perform computations, interac...
The sonification of seismic data can provide a fascinating and instructive complement to the ``wiggly line'' representation of earthquake time series used in the classical seismogram. Broadband recordings of earthquakes and other ground motions provide a rich variety of waveforms and spectral content: from the short duration, high frequency and imp...
What is EarthScope? The answer to this question can best be addressed through images, movies and interactive visualizations. Using these types of visual tools the temporal evolution and spatial scales of the various EarthScope data (e.g., earthquakes, sediment thickness, aquifers, focal mechanisms, topography, moho depth, mines, geology, magnetics,...
News coverage showing collapsed buildings, broken bridges and smashed cars help middle school students visualize the hazardous nature of earthquakes. However, few students understand how scientists investigate earthquakes through analysis of data collected using technology devices from around the world. The important findings by Muawia Barazangi an...
"There is little doubt that K-12 students need to understand and appreciate the Earth on which they live. They can achieve this understanding only if their teachers are well prepared". Dan Barstow, Director of Center for Earth and Space Science Education at TERC. The approach of San Diego County's Cyberinfrastructure Training, Education, Advancemen...
Within the scientific community, interdisciplinary analyses are increasingly emphasized to gain a more complete understanding of how entire Earth systems function. For National Science Foundation (NSF)-sponsored programs such as EarthScope (http://www.earthscope.org), Ridge 2000 (http://www.ridge2000.org), Margins (http://www.nsf-margins.org), and...
The causes of the catastrophic eruption of the Lusi mud volcano in Indonesia are hotly debated. Data from a nearby exploration well and a new look at the stress regime suggest that drilling operations, and not an earthquake set the eruption off.
Looking at data from perspectives other than map view, or standard cross sections, can help researchers with their science. Interactively exploring visualizations of multi-dimensional data allows scientists to assess the quality of their data, identify links between different data types, assist with project planning, refine their hypotheses and mor...
Recently ( AGU Full Meeting 2004, 2005 ) we discussed the influence of seismic scattering in anisotropic rock on the S-coda waves attenuation, coda quality factor Qc and intensity of back scattering energy, Cc. Now we improve our method of anisotropy study based on coda waves of 102 3-components records from 11 local earthquakes, ml = 4.0 - 5.0 of...
1] Various studies have examined remote earthquake triggering in geothermal areas, but few studies have investigated triggering in nongeothermal areas. We search the ANZA (southern California) network catalog for evidence of remote triggering. Using three statistical tests (binomial, Kolmogorov-Smirnov, and Wilcoxon rank sum), we determine the sign...
We examine aftershock detectability thresholds for events in the initial part of the 31 October 2001, M-L 5.1 sequence in southern California. This sequence occurred directly below the broadband ANZA seismic network, which recorded continuous waveform data at 13 azimuthally well-distributed stations within the study region (seven had epicentral dis...
We examine the potential triggering relationship between large earthquakes and methane mud volcano eruptions. Our data set consists of a 191-year catalog (1810–2001) of eruptions from 77 volcanoes in Azerbaijan, central Asia, supplemented with reports from mud volcano eruptions in Japan, Romania, Pakistan, and the Andaman Islands. We compare the oc...
We explore the idea that fluid occurrence below the seismogenic zone plays an active role in the rupture process by examining how fluids spatially relate to seismicity at three continental plate boundaries: South Island of New Zealand, the Himalaya, and San Andreas fault, USA. With this objective, we project earthquake hypocenters onto magnetotellu...
The most effective means of communicating science to today's "high-tech" students is through the use of visually attractive and animated lessons, hands-on activities, and interactive Internet-based exercises. To address these needs, we have developed Earthquakes in Action, a summer high school enrichment course offered through the California State...
With the advances in the collection of greater quantities of higher caliber data, the field geophysics demands a new device to appropriately synthesize and compare the continuously-incoming slew of heterogeneous datasets from various branches of earth science. These data include earthquakes, sediment thickness, focal mechanisms, topography, tomogra...
Scientists from the Scripps Institution of Oceanography (SIO) Visualization Center and science educators from the Birch Aquarium at Scripps (BAS) and Aquatic Adventures Science Education Foundation (AASEF) collaborated to create Seismic Sleuths, a field trip experience for 6th graders that introduces concepts in global tectonics and seismicity usin...
Collaborative visualization of large-scale datasets across geographically distributed sites is becoming increasingly important for Earth Sciences. Not only does it enhance our understanding of the geological systems, but also enables near-real-time scientific data acquisition and exploration across distant locations. While such a collaborative envi...
We estimate the strike and dip of three California fault segments (Cal- averas, Sargent, and a portion of the San Andreas near San Jaun Bautistia) based on principle component analysis of accurately located microearthquakes. We compare these fault orientations with two different first-motion focal mechanism catalogs: the Northern California Earthqu...
Scientists at the Scripps Institution of Oceanography (SIO; La Jolla, Calif.) have created interactive three‐dimensional (3‐D) visualizations of the 3 May magnitude 8.0 earthquake that occurred near Neiafu,Tonga. The earthquake occurred at 1526 UTC at a depth of 16 kilometers (as recorded by the USArray seismic network operated at SIO, http://anf.u...
We studied the energy distribution of seismic scattering based on the source factor results ( SF in the single -backscattering model of Aki and Chouet, 1975, JGR ) obtained from polarization -dependent S-coda amplitudes. We have tested our algorithm on band-passed ( 2 - 4 Hz ) waveforms of a ML}= 5.1 local crustal earthquake ( h = 18.7 km ) recorde...
The M 5.2 earthquake (June 12, 2005) in the Anza region was preceded by a M 5.1 event (October 31, 2001) about 7 km to the southeast. Both earthquakes occurred near 17 km depth in the San Jacinto fault zone within the Anza seismic gap, and were followed by productive aftershock sequences. It is unclear if they occurred on a northwest-striking fault...
Various studies have examined remote earthquake triggering in geothermal areas, but few studies have sought out triggering in non-geothermal areas. We search the 22-year ANZA (southern California) network catalog for evidence of remote triggering. Using three statistical tests (Binomial, Wilcoxon Ranksum and Kolmogorov-Smirnov) we determine the sig...
Authentic practice in science requires access to phenomena. In this paper, we introduce RoomQuake, an application designed to foster the growth of a community of learning around scientific practice in seismology. Rather than treating seismic activity as remote events, RoomQuake seeks to enhance salience by situating those phenomena directly in the...
The current rate of Mars exploration data acquisition demands that geoscientists and computer scientists coordinate central storage, processing and visualization strategies to anticipate future technological advancements. We investigate how existing 3-D visualization tools can be used to study a part of the Mars orbiter and lander data (about 4 ter...
Scientists and visualization experts at the Scripps Institution of Oceanography have created an interactive three‐dimensional visualization of the 28 March 2005 magnitude 8.7 earthquake in Sumatra. The visualization shows the earthquake's hypocenter and aftershocks recorded until 29 March 2005, and compares it with the location of the 26 December 2...
On 10/31/2001, a M5.1 earthquake occurred in the middle of the ANZA network (7 24-bit broadband stations were within 20 km of the epicenter) that spans the San Jacinto fault zone in southern California. A high pass filter (f > 1.0 Hz) was used to identify seismic arrival times of the aftershocks and in turn determine the aftershock locations. In th...
The high-frequency spectrum of ground motions in Guerrero, Mexico and in Nevada and California has been examined from the perspective of the parameter "kappa". The main feature of the high frequency spectrum (i.e. above the corner frequency) can be approximated as proportional to exp(-pi*kappa*f). Based on a distance dependence, Anderson and Hough...
We have been studying attenuation parameter kappa using recordings from the Southern Great Basin Digital Seismic Network in support of site and engineering characterization of the Yucca Mountain area in southern Nevada. Earthquake magnitudes range from 0 to 4.4, with 18 of M>=3.0. Kappa is estimated from the residual spectral slope after removing a...
We present a method to study crustal anisotropy using polarization-dependence attenuation of S-coda waves. We have tested our algorithm on band-passed ( 2 - 4 Hz ) waveforms of a ML = 5.1 local crustal earthquake ( h = 18.7 km ) recorded by the ANZA broadband network in southern California. We analyzed the records of 10 stations, of which 7 are < 2...
Extending Earth Science learning activities from 2D to 3D was central to this year's second annual Teacher Education Workshop, which was held at the Scripps Institution of Oceanography's Visualization Center (SIO VizCenter; http://siovizcenter.ucsd.edu/). Educational specialists and researchers from several institutions led this collaborative works...