Advanced National Seismic System Research Articles

Seismic Hazard Assessment in Maluku Province Using PSHA

On 10 January 2023, a strong earthquake with a moment magnitude (Mw) of 7.5 occurred in Banda Sea, Maluku Province. This earthquake caused casualties around the epicentre due to the building collapse which was not an earthquake-resistant structure. A high level of seismic vulnerability and non-standard infrastructure often result in large losses when earthquakes occur. Therefore, mapping of earthquake-prone areas needs to be carried out to optimize the mitigation efforts based on Peak Ground Acceleration (PGA) and Spectrum Acceleration (SA) values. In this paper, mitigation efforts are carried out by mapping earthquake-prone areas using Probabilistic Seismic Hazard Analysis (PSHA) which considers the potential of each complex earthquake source in Maluku Province. Input data was obtained from several earthquake catalogues such as Advanced National Seismic System (ANSS), International Seismological Center (ISC), and United States Geological Survey (USGS) which were processed and analyzed using the Matlab, ZMap, and R-CRISIS programs and mapped using the ArcMap program. The results of PSHA show that Maluku Province is a region with varying levels of earthquake vulnerability. The research results show that the distribution hazard value on PGA in Maluku Province reaches 0.02g to 0.48g for a return period of 500 years and 0.04g to 0.79g for a return period of 2,500 years and on SA for periods of 0.20 seconds and 1.00 second reaches 0.04g to 0.89g and 0.01g to 0.22g for a return period of 500 years and 0.07g to 1.48g and 0.02g to 0.35g for a return period of 2,500 years, respectively. The highest level of vulnerability is in the northern region including Seram Island, Way Apu Island and Ambon Island and the lowest level of vulnerability is in the eastern region including Aru Island.

Estimation of the Probability of Earthquakes Return Period in Zimbabwe Using Gumbel’s Extreme Value Theory Method

Using Gumbel's extreme value theory method, this study looked into the probability of the largest earthquakes for different return periods in Zimbabwe. The Advanced National Seismic System (ANSS), the Northern California Earthquake Data Centre website, and UC Berkeley in the United States provided the data used for this study. The natural earthquakes with Mb ≥ 4.0 that occurred in the study area between January 1, 1901 and December 31, 2001 (a period of 100 years) with a focal depth ranging from 0 to 700 km made up the selected data. The study area is between 150S - 220S and 250E -340E in coordinates. A total of 81 events were used in the investigation. According to the results, there is a 100% chance that earthquakes with a magnitude between 4.5 and 5.5 will occur during the time interval of approximately 1 to 14 years and a 9.5% chance that within the next 100 years, there will be an earthquake with a magnitude of Mb = 6.0 or higher. For magnitudes Mb = 6.0 and above, the return period is relatively long - roughly 50 – 701 years. This suggests that there is little chance that Zimbabwe will experience earthquakes larger than magnitude 6.0. Despite being low, it is impossible to forecast with certainty because earthquake forecasting and prediction is still a complex topic.

1D Seismic Velocity Models for West-Central and Western Montana

Abstract In seismically active areas with infrequent large-magnitude earthquakes, high-quality seismic data are critical for determining accurate seismic velocity models. Here, we present a new local-scale crustal seismic velocity model in west-central Montana as well as a new regional-scale crustal and upper mantle seismic velocity model for broader western Montana. These models are constrained by phase arrivals from several seismic networks, including the University of Montana Seismic Network, the Montana Regional Seismic Network, the Advanced National Seismic System, temporary deployments by the U.S. Geological Survey, and the USArray Transportable Array. We jointly invert for hypocenters and velocity structure using the VELEST software. The local seismic velocity model is the first model specific to west-central Montana, using P-wave arrivals from aftershocks of the 2017 M 5.8 Lincoln, Montana, earthquake. The local model consists of eight layers down to 30 km depth below the mean sea level and spans a region of approximately 40,​000 km2 (200 km × 200 km). The velocity of the uppermost layer in the local model is 4.80 ± 0.11 km/s, and the velocity of the lowermost layer resolved from the data is 7.00 ± 0.05 km/s. Using an expanded dataset across a broader geographical area, we develop a “regional” seismic velocity model that represents spatially averaged velocity structure across western Montana. The regional model consists of thirteen layers down to 45 km depth below the sea level and is appropriate to an area of 160,​000 km2 (400 km × 400 km). The velocity of the uppermost layer is 4.30 ± 0.15 km/s, and the velocity of the lowermost layer is 8.00 ± 0.04 km/s. The new models are similar to prior velocity models for western Montana, but feature improved vertical resolution of layer velocities.

Modern Products for a Vintage Event: An Update on the 1933 Long Beach, California, Earthquake

Abstract When a notable earthquake occurs in the United States, a range of familiar real- and near-real-time products are produced by the U.S. Geological Survey (USGS) Advanced National Seismic System (ANSS), and made available via the ANSS Comprehensive Earthquake Catalog. For historical and early instrumental earthquakes, similar results and products are developed depending on data availability and event significance, drawing from published later studies. The year 2023 marked the ninetieth anniversary of the 11 March 1933 Long Beach, California, earthquake. This anniversary provided the impetus to update ANSS products, drawing on archived and published data. Here, we describe the updated ShakeMap, shaking recordings and intensities, and retrospective aftershock forecast for the Long Beach, California, earthquake. In effect we have developed standard, modern ANSS products for an earthquake that occurred 90 yr ago. Our results show that the distributions of both the ground motions, anchored by three strong-motion recordings, and aftershock magnitudes are consistent with expectations for an M 6.4 mainshock in Southern California. We show that, notwithstanding possible limitations, instrumentally recorded accelerations from the closest station are consistent with predicted shaking and directly estimated macroseismic intensities. Updated data products have been added to the USGS event page, where they are available for download. Public-facing products were also created for the anniversary and are freely available on the USGS website.

Manmade earthquakes and healthcare visits for anxiety disorders in Oklahoma, 2010-2019.

Using data from a nationwide United States patient-level commercial and Medicare Advantage claims database from 2010 to 2019, we identified healthcare encounters for anxiety disorders using diagnostic codes and subclassified them as adjustment reaction; anxiety-related disorders; physical symptoms of anxiety; and stress disorders. With U.S. Geological Survey Advanced National Seismic System data, we generated county-level 6-month rolling counts of felt earthquakes (≥M 4) and linked them to patient residential county at the time of the healthcare visit. In this repeated measures, individual-level analysis we used generalized estimating equations to estimate the odds of monthly anxiety-related healthcare visits as a function of the frequency of ≥M 4 earthquakes in the previous 6 months. We identified 4,594 individuals in Oklahoma observed from 2010 to 2019. For every additional five ≥M 4 earthquakes in the preceding 6 months, the odds of healthcare visits for stress disorders increased (odds ratio [OR] = 1.27; 95% confidence interval [CI] = 1.03, 1.57). We found no evidence of an association with adjustment reaction (OR = 1.05; 95% CI = 0.89, 1.23), anxiety-related disorders (OR = 0.96; 95% CI = 0.90, 1.03), or physical symptoms of anxiety (OR = 1.03; 95% CI = 0.98, 1.09). We report an association between increased frequency of felt earthquakes and treatment seeking for stress disorders. This finding should motivate ongoing study of the potential consequences of the oil and gas industry for mental health outcomes including anxiety disorders.

Lower Seismogenic Depth Model for Western U.S. Earthquakes

Abstract We present a model of the lower seismogenic depth of earthquakes in the western United States (WUS) estimated using the hypocentral depths of events M > 1, a crustal temperature model, and historical earthquake rupture depth models. Locations of earthquakes are from the Advanced National Seismic System Comprehensive Earthquake Catalog from 1980 to 2021 supplemented with seismicity in southern California for event hypocenters that were relocated by Hauksson et al. (2012) to obtain higher precision and better resolution in the model. We calculated the average depth of the deepest 10% of the merged catalog using an adaptive radius of 50 km or more. Along the San Andreas fault, the deepest seismogenic depths are located at 23 km around the Cholame segment, whereas the shallowest depths are located at about 10 km along the Rodgers Creek and Maacama faults. For the WUS outside California, the depth generally varies between 10 and 25 km with an average around 14 km but could extend to 35 km along Cascadia subduction zone. We find good agreement between the small-magnitude depths and rupture depths derived from coseismic slip of large earthquakes across the region. Our estimates are generally deeper than the previous seismogenic depths determined for the Uniform California Earthquake Rupture Forecast, Version 3 model based on work by Petersen et al. (1996) who used seismicity cross sections along major fault zones in California. Our new seismogenic depth distribution correlates closely with crustal temperature derived from WUS heat flow (Blackwell et al., 2011). This correlation allowed us to develop a map of the brittle–ductile transition that we use to replace seismogenic depths in the model east of the Intermountain West Seismic Belt where the seismicity rate is low. This updated depth model is useful for recalibrating the lower geologic fault rupture depths, and constraining deformation and seismicity source models in updates of the U.S. Geological Survey National Seismic Hazard Model.

Nearest Neighbor Method for Discriminating Aftershocks and Duplicates When Merging Earthquake Catalogs

Early aftershocks contain important information about the physics of earthquake occurrence and postseismic relaxation processes. However, the standard catalogs of early aftershocks are usually incomplete. Many events can be missed in the main shock coda, some of which are strong enough due to the extremely high noise level. Under these conditions, the process of event identification becomes largely stochastic. Due to different network configurations and record processing methods, different agencies may register/miss different events, thus merging catalogs can improve the completeness of the aftershock sequence. When merging catalogs, the problem of identifying duplicates (records related to the same seismic event) arises. The main difficulty is discriminating aftershocks and duplicates, since both are events close in space and time. The problem is analogous to the problem of discriminating aftershocks and independent events. The solution methods are usually similar too. In this paper, we apply the nearest neighbor method modified for our problem. This method has become widespread in recent years in the problem of identifying aftershocks, and a probabilistic metric in the space of network errors in determining the epicenters and times of seismic events. It is applied for automatic identification of duplicates when merging catalogs of aftershocks for the Tohoku earthquake. An analysis of the space-time structure of duplicates and aftershocks shows their significant difference, which makes it possible to successfully solve the problem. In a sample from the global Advanced National Seismic System (ANSS) catalog (M> 4), were found more than 700 events missed by the Japan Meteorological Agency (JMA) seismic network, which is one of the best in the world. Among the misses, there are several events with M> 6 in the first hours after the main shock. Duplicate identification reliability is >97%. The method can be used to improve the completeness of aftershock sequences. The reliable identification of duplicates allows, in addition, to study the correspondence of the magnitudes determined by different agencies. Therefore the present method is an effective tool for creating merged catalogs of earthquakes with a uniform magnitude.

On the Depth of Earthquakes in the Delaware Basin: A Case Study along the Reeves–Pecos County Line

Abstract Increased rates of seismicity in the Delaware basin, Texas, accompanying unconventional petroleum development have created intensive interest in determining their cause. Detailed and accurate spatial distribution of seismicity and focal mechanisms are critical components for understanding the underlying industrial processes responsible for inducing seismicity. We focus on a highly seismically active area straddling the Reeves–Pecos County line where two TexNet stations sit atop the seismicity, which includes 21 ML 3+ events from 2017 to 2020 (Advanced National Seismic System Comprehensive Earthquake Catalog). Short epicentral distance enables us to reliably estimate the hypocentral depth using seismic phase picks and standard location methods. We use a deep-learning-based method to detect earthquakes and time the phase arrivals. Hypocentral locations computed in a velocity model constrained by local well data reveal that the seismicity concentrates between 1.5 and 2.5 km below ground in the Delaware Mountain Group, the primary wastewater disposal zone at this location. Waveform inversions for the moment tensor and focal depth independently confirm the shallow depths. The moment tensor solutions define critically stressed high-angle normal faults, suggesting a causal connection between injection and seismicity.

Seismic Monitoring during Crises at the NEIC in Support of the ANSS

Abstract Over the past two decades, the U.S. Geological Survey (USGS) National Earthquake Information Center (NEIC) has overcome many operational challenges. These range from minor disruptions, such as power outages, to significant operational changes, including system reconfiguration to handle unique earthquake sequences and the need to handle distributed work during a pandemic. Our ability to overcome crises is built on the development and implementation of a continuity of operations plan, well-designed infrastructure, adaptive software systems, experienced staff, and extensive collaboration. The NEIC does not operate in a vacuum but benefits from contributions of United States and international seismic networks. Similarly, the overall resilience of earthquake monitoring in the United States and around the globe benefits from the NEIC’s role as the national center for the Advanced National Seismic System (ANSS). Here, we highlight significant adaptations the NEIC has made in the face of crises. We discuss the COVID-19 pandemic, which represents the most significant operational crisis to impact the NEIC. The NEIC has maintained continuous operations during the ongoing COVID-19 pandemic by shifting from a fully onsite operations center to a distributed hybrid of onsite and telework staffing. We then discuss cases in which the NEIC has supported regional monitoring in the face of significant crises. In 2018, the NEIC assisted the Hawaiian Volcano Observatory with the Kīlauea volcano eruption by responding to large events, implementing contingency monitoring procedures, and calculating moment magnitudes for the low-frequency caldera collapses. Impacts of a crisis extend beyond the immediate response and often require a significant postevent assessment and a rebuilding phase. After the 2017 Hurricane Maria, the NEIC, the USGS National Strong-Motion Program, and the USGS Albuquerque Seismological Laboratory worked with the Puerto Rico Seismic Network and the Puerto Rico Strong-Motion program to assess, plan, and implement upgrades at sites that experienced storm damage.

New Insights into the Lake Erie Fault System from the 2019 ML 4.0 Ohio Earthquake Sequence

AbstractWe present a detailed analysis of the 10 June 2019 ML 4.0 Ohio earthquake sequence, which is the largest earthquake that struck Lake County, northeastern Ohio, since 1986. This sequence is well recorded by local seismic networks, which provides an unprecedented opportunity to understand the local seismotectonics. We utilize a waveform-based cross-correlation method to identify ∼12 times more events than reported by the Advanced National Seismic System (ANSS) Comprehensive Earthquake Catalog: the whole sequence started with several small earthquakes (ML 1–2) beginning 12 March 2019, and the last one occurred ∼1min immediately before the ML 4.0 mainshock; many previously unreported aftershocks (ML 0.3–2.2) are found, which were active for the first week after the mainshock; another major sequence with a 7 December 2019 ML 2.6 mainshock occurred and also started with a few smaller events beginning in mid-November and was followed by its own aftershocks. The relocated seismicity delineates a linear feature, orientation of which is consistent with the resolved focal plane that may correspond to the ruptured fault. Our results highlight that closer monitoring of local seismicity is crucial for understanding the seismotectonics and mitigating future seismic hazard around the southern Great Lakes.

Nevada Seismological Laboratory Rapid Seismic Monitoring Deployment and Data Availability for the 2020 Mww 6.5 Monte Cristo Range, Nevada, Earthquake Sequence

Abstract The Nevada Seismological Laboratory (NSL) at the University of Nevada, Reno, installed eight temporary seismic stations following the 15 May 2020 Mww 6.5 Monte Cristo Range earthquake. The mainshock and resulting aftershock sequence occurred in an unpopulated and sparsely instrumented region of the Mina deflection in the central Walker Lane, approximately 55 km west of Tonopah, Nevada. The temporary stations supplement NSL’s permanent seismic network, providing azimuthal coverage and near-field recording of the aftershock sequence beginning 1–3 days after the mainshock. We expect the deployment to remain in the field until May 2021. NSL initially attempted to acquire the Monte Cristo Range deployment data in real time via cellular telemetry; however, unreliable cellular coverage forced NSL to convert to microwave telemetry within the first week of the sequence to achieve continuous real-time acquisition. Through 31 August 2020, the temporary deployment has captured near-field records of three aftershocks ML≥5 and 25 ML 4–4.9 events. Here, we present details regarding the Monte Cristo Range deployment, instrumentation, and waveform availability. We combine this information with waveform availability and data access details from NSL’s permanent seismic network and partner regional seismic networks to create a comprehensive summary of Monte Cristo Range sequence data. NSL’s Monte Cristo Range temporary and permanent station waveform data are available in near-real time via the Incorporated Research Institutions for Seismology Data Management Center. Derived earthquake products, including NSL’s earthquake catalog and phase picks, are available via the Advanced National Seismic System Comprehensive Earthquake Catalog. The temporary deployment improved catalog completeness and location quality for the Monte Cristo Range sequence. We expect these data to be useful for continued study of the Monte Cristo Range sequence and constraining crustal and seismogenic properties of the Mina deflection and central Walker Lane.

Is the Aftershock Zone Area a Good Proxy for the Mainshock Rupture Area?

ABSTRACTThe locations of aftershocks are often observed to be on the same fault plane as the mainshock and used as proxies for its rupture area. Recent developments in earthquake relocation techniques have led to great improvements in the accuracy of earthquake locations, offering an unprecedented opportunity to quantify both the aftershock distribution and the mainshock rupture area. In this study, we design a consistent approach to calculate the area enclosed by aftershocks of 12 Mw≥5.4 mainshocks in California, normalized by the mainshock rupture area derived from slip contours. We also investigate the Coulomb stress change from mainshock slip and compare it with the aftershock zone. We find that overall, the ratios of aftershock zone area to mainshock rupture area, hereinafter referred to as “aftershock ratio”, lie within a range of 0.5–5.4, with most values being larger than 1. Using different slip-inversion models for the same mainshock can have a large impact on the results, but the ratios estimated from both the relocated catalogs and Advanced National Seismic System catalog have similar patterns. The aftershock ratios based on relocated catalogs of southern California fall between 0.5 and 4.3, whereas they exhibit a wider range from 1 to 5.4 for northern California. Aftershock ratios for the early aftershock window (within one-day) show a similar range but of smaller values than using the entire aftershock duration, and we propose that continuing afterslip could contribute to the expanding aftershock zone area following several mainshocks. Our results show that areas with positive Coulomb stress change scale with aftershock zone areas, and spatial distribution of aftershocks represents stress release from mainshock rupture and continuing postseismic slip.

Natural Seismicity in and around the Rome Trough, Eastern Kentucky, from a Temporary Seismic Network

AbstractThe Rome trough is a northeast-trending graben system extending from eastern Kentucky northeastward across West Virginia and Pennsylvania into southern New York. The oil and gas potential of a formation deep in the trough, the Rogersville shale, which is ∼1 km above Precambrian basement, is being tested in eastern Kentucky. Because induced seismicity can occur from fracking formations in close proximity to basement, a temporary seismic network was deployed along the trend of the Rome trough from June 2015 through May 2019 to characterize natural seismicity.Using empirical noise models and theoretical Brune sources, minimum detectable magnitudes, Mmin, were estimated in the study area. The temporary stations reduced Mmin by an estimated 0.3–0.8 magnitude units in the vicinity of wastewater-injection wells and deep oil and gas wells testing the Rogersville shale. The first 3 yr of seismicity detected and located in the study area has been compiled. Consistent with the long-term seismicity patterns in the Advanced National Seismic System Comprehensive Catalog, very few earthquakes occurred in the crust beneath the Rome trough—only three events were recorded—where the temporary network was most sensitive. None of these events appear to have been associated with Rogersville shale oil and gas test wells. Outside of the trough boundary faults, earthquakes are diffusely distributed in zones extending into southern Ohio to the north, and into the eastern Tennessee seismic zone to the south. The orientations of P axes from the seven first-motion focal mechanisms determined in this study are nearly parallel with both the trend of the Rome trough and with the orientation of maximum horizontal compressive stress in the region. This apparent alignment between the regional stress field and the strikes of faults in the trough at seismogenic depths may explain the relative lack of earthquake activity in the trough compared with the surrounding crust to the north and south.

Evaluation of Earthquake Magnitude Estimation and Event Detection Thresholds for Real-Time GNSS Networks: Examples from Recent Events Captured by the Network of the Americas

Abstract Several studies have shown that real-time (RT) Global Navigation Satellite Systems (GNSS) measurements can provide an estimate of an earthquake’s moment magnitude (Mw) using scaling laws that relate peak ground displacements (PGDs) and hypocentral distance with Mw. In this study, we use data from GNSS stations operated by UNAVCO as part of the National Science Foundation Geodetic Facility for the Advancement of Geoscience (GAGE) that comprises the Network of the Americas (NOTA) to show that precise point positioning (PPP) solutions distributed in RT during five recent earthquakes could be used to calculate Mw rapidly and reliably. We analyze solutions distributed by UNAVCO during the 8 September 2017 Mw 8.2 Tehuantepec, Mexico, 10 January 2018 Mw 7.5 Great Swan Island, Honduras, 23 January 2018 Mw 7.9 Gulf of Alaska earthquake, and the 4 July 2019 Mw 6.4 and 6 July 2019 Mw 7.1 Ridgecrest, California, earthquakes. We find that RT-GNSS Mw estimates consistent with Advanced National Seismic System Comprehensive Earthquake Catalog values are available tens of seconds to a few minutes after the event origin time. The speed with which an estimate is available is dependent on the proximity to the epicenter of the closest NOTA stations. The results demonstrate that RT-GNSS networks could be used to mitigate the problem of magnitude saturation observed in seismic-based earthquake early warning (EEW) systems. RT-GNSS effectively expands the spectrum of events for which a seismic EEW system can provide accurate warnings of impending ground shaking and provides an independent verification of seismically derived magnitudes. We also analyze the RT-PPP solutions from more than 800 RT-GNSS stations to determine the ambient-noise levels of each NOTA station and combine that with PGD magnitude scaling laws to construct regional network sensitivity maps for the NOTA network. Such maps may be used to determine “blind spots” or regions of lower sensitivity in RT-GNSS networks under consideration for EEW.

Probabilistic estimation of seismic parameters for Bangladesh

This paper estimates the following seismic parameters: the maximum recorded magnitude (Mmax), the Gutenberg-Richter b-value, the annual rate of exceedance of particular magnitude, and return period of that magnitude are examined. The catalog is extracted from the Advanced National Seismic System (ANSS) catalog. The working catalog, originated from longitude 87 to 93 and latitude 20 to 27 that covers the whole Bangladesh and some parts of India and Myanmar, contains 406 events from 1918 to 2017. To define the working catalog, magnitudes were converted into moment magnitude. All parameters had been calculated from the time-independent catalog. Since no formula available in the literature to calculate the confidence interval for annual rate and return period, the confidence interval of the estimates were calculated using simulation technique. For this case, 100,000 simulations were considered and calculated 0.025th and 0.975th quantiles of the simulated values as 95% confidence interval.

Open-Source ANSS Quake Monitoring System Software

AbstractANSS stands for the Advanced National Seismic System of the U.S.A., and ANSS Quake Monitoring System (AQMS) is the earthquake management system (EMS) that most of its member regional seismic networks (RSNs) use. AQMS is based on Earthworm, but instead of storing files on disk, it uses a relational database with replication capability to store pick, amplitude, waveform, and event parameters. The replicated database and other features of AQMS make it a fully redundant system. A graphical user interface written in Java, Jiggle, is used to review automatically generated picks and event solutions, relocate events, and recalculate magnitudes. Add-on mechanisms to produce various postearthquake products such as ShakeMaps and focal mechanisms are available as well. It provides a configurable automatic alarming and notification system. The Pacific Northwest Seismic Network, one of the Tier 1 ANSS RSNs, has modified AQMS to be compatible with a freely available, capable, open-source database system, PostgreSQL, and is running this version successfully in production. The AQMS Software Working Group has moved the software from a subversion repository server hosted at the California Institute of Technology to a public repository at gitlab.com. The drawback of AQMS as a whole is that it is complex to fully configure and comprehend. Nevertheless, the fact that it is very capable, documented, and now free to use, might make it an attractive EMS choice for many seismic networks.

The Oklahoma Geological Survey Statewide Seismic Network

AbstractThe Oklahoma Geological Survey (OGS) monitors seismicity throughout the state of Oklahoma utilizing permanent and temporary seismometers installed by OGS and other agencies, while producing a real-time earthquake catalog. The OGS seismic network was recently added to the Advanced National Seismic System (ANSS) as a self-supporting regional seismic network, and earthquake locations and magnitudes are automatically reported through U.S. Geological Survey and are part of the ANSS Comprehensive Earthquake Catalog. In Oklahoma, before 2009, background seismicity rates were about 2 M 3.0+ earthquakes per year, which increased to 579 and 903 M 3.0+ earthquakes in 2014 and 2015, respectively. After seismicity peaked, the rate fell to 624, 304, and 194 M 3.0+ earthquakes in 2016, 2017, and 2018, respectively. The catalog is complete down to M 2.2 from mid-2014 to present, despite the significant workload for a primarily state-funded regional network. That astonishing uptick in seismicity has been largely attributed to wastewater injection practices. The OGS provides the Oklahoma Corporation Commission, the agency responsible for regulating oil and gas activities within the state, with technical guidance and earthquake products that inform their “traffic-light” mitigation protocol and other mitigating actions. We have initiated a citizen-scientist-driven, educational seismometer program by installing Raspberry Shake geophones throughout the state at local schools, museums, libraries, and state parks. The seismic hazard of the state portends a continued need for expansion and densification of seismic monitoring throughout Oklahoma.

Current Status and Future of Regional Seismic Network Monitoring in the Central and Eastern United States

AbstractThe central and eastern United States (CEUS) is an area of generally low-to-moderate seismic hazard with a number of large cities with high seismic risk, a history of occasional damaging earthquakes, and seismic activity induced by wastewater disposal. Seismic monitoring in the CEUS, which began at the beginning 1900s, has undergone many changes through time. Over the past two decades, broadband digital seismic stations connected by internet communications have become widespread. Modern data processing systems to automatically locate earthquakes and assign event magnitudes in near-real time have become the norm, and, since the inception of the Advanced National Seismic System in 2000, more than 10,000 earthquakes have been located and cataloged. Continuously recorded digital seismic data at 100 samples per second are allowing new avenues of research into earthquake source parameters, ground-motion excitation, and seismic wave propagation. Unfortunately, over the past two decades the number of regional seismic network (RSN) centers has diminished due to consolidations and terminations, as funding has tightened. Nevertheless, the public in different parts of the CEUS still looks to local experts for information when earthquakes take place or when they have questions about earthquakes and seismic hazard. The current RSNs must evolve to encompass the need for local seismic information centers and to serve the needs of present and future research into the causes and effects of CEUS earthquakes.

Beyond Earthworm: Keeping the Promise

AbstractThe founding of the Advanced National Seismic System (ANSS) vision was originally presented in U.S. Geological Survey Circular 1188 (U.S. Geological Survey [USGS], 1999), after many years of discussions and workshops, described in detail by Filson and Arabasz (2016). Much has been accomplished in the ensuing two decades. Disparate and sometimes divergent developments that had been previously explored at individual private and public universities were finally centralized with increased efficiency and coherency of effort. The stated mission of the ANSS is to “… provide accurate and timely data and information products for seismic events, including their effects on buildings and structures, employing modern monitoring methods and technologies.” In this article, an approach (xQuake) is proposed that does not interfere in any way with the mission of the National Earthquake Information Center and ANSS but instead restores much of the community focus and international collaboration that has been lost over the past two decades. xQuake uses an executable graph framework in a pipeline architecture; this framework can be seamlessly integrated into current ANSS quake monitoring systems. This new approach incorporates modern approaches to computer analytics, including multitopic Kafka exchange rings, cloud computing, a self-configuring phase associator, and machine learning. The xGraph system is free for noncommercial use, open source, hardware agnostic (Windows, Linux, Mac), with no requirement for commercial datastores.

Forecasting the Full Distribution of Earthquake Numbers Is Fair, Robust, and Better

Forecasting the full distribution of the number of earthquakes is revealed to be inherently superior to forecasting their mean. Forecasting the full distribution of earthquake numbers is also shown to yield robust projections in the presence of surprise large earthquakes, which in the past have strongly deteriorated the scores of existing models. We show this with pseudo-prospective experiments on synthetic as well as real data from the Advanced National Seismic System (ANSS) database for California, with earthquakes with magnitude larger than 2.95 that occurred between the period 1971-2016. Our results call in question the testing methodology of the Collaboratory for the study of earthquake predictability (CSEP), which amounts to assuming a Poisson distribution of earthquake numbers, which is known to be a poor representation of the heavy-tailed distribution of earthquake numbers. Using a spatially varying ETAS model, we demonstrate a remarkable stability of the forecasting performance, when using the full distribution of earthquake numbers for the forecasts, even in the presence of large earthquakes such as Mw 7.1 Hector Mine, Mw 7.2 El Mayor-Cucapah, Mw 6.6 Sam Simeon earthquakes, or in the presence of intense swarm activity in Northwest Nevada in 2014. While our results have been derived for ETAS type models, we propose that all earthquake forecasting models of any type should embrace the full distribution of earthquake numbers, such that their true forecasting potential is revealed.