Skip Nav Destination
Close Modal
![First thumbnail for: An Earthquake Early Warning System for Northern Ch...]()
![Second thumbnail for: An Earthquake Early Warning System for Northern Ch...]()
![Third thumbnail for: An Earthquake Early Warning System for Northern Ch...]()
![First thumbnail for: Optimizing Earthquake Early Warning Performance: <...]()
![Second thumbnail for: Optimizing Earthquake Early Warning Performance: <...]()
![Third thumbnail for: Optimizing Earthquake Early Warning Performance: <...]()
![First thumbnail for: Implementing the <span class="search-highlight">El...]()
![Second thumbnail for: Implementing the <span class="search-highlight">El...]()
![Third thumbnail for: Implementing the <span class="search-highlight">El...]()
![First thumbnail for: Designing a Network‐Based Earthquake Early Warning...]()
![Second thumbnail for: Designing a Network‐Based Earthquake Early Warning...]()
![Third thumbnail for: Designing a Network‐Based Earthquake Early Warning...]()
![First thumbnail for: Testing <span class="search-highlight">ElarmS</spa...]()
![Second thumbnail for: Testing <span class="search-highlight">ElarmS</spa...]()
![Third thumbnail for: Testing <span class="search-highlight">ElarmS</spa...]()
![First thumbnail for: The Potential for Earthquake Early Warning in Ital...]()
![Second thumbnail for: The Potential for Earthquake Early Warning in Ital...]()
![Third thumbnail for: The Potential for Earthquake Early Warning in Ital...]()
![Same as Figure 3 for the 1 July 2015 Mw 8.2 ElarmS false alarm at the time of the first ElarmS report (34 s after the OT reported by ElarmS). The P‐ and S‐wave positions are drawn relative to the location and OT of the ElarmS false earthquake source. ElarmS predicts large motions at stations that have no apparent motion, guiding the CDM to assign an almost 97.5% probability that this is a false alarm. Numbers in circles identify locations for which PDFs of expected ground motion are plotted in Figure 7.]()
![Illustration of the new split event check criteria. Each circle represents a subsequent ElarmS‐2 solution compared to the first ElarmS‐2 solution for a split earthquake. The horizontal axis is the difference in estimated origin time, and the vertical axis shows the horizontal distance between the two solutions. PNW ElarmS‐2 now rejects a subsequent ElarmS‐2 trial solution if it falls between the two lines. Previously ElarmS‐2 rejected a split event solution only if its origin time was within 15 s of an existing event and its location was within 90 km (rectangular box).]()
![(a) Final observed peak horizontal shaking intensity for the 2014 Mw 6 South Napa earthquake. The triangles are the locations of stations used in this analysis. All other symbols are the same as in Figure 3. (b,c) Hypocenter location (star) and predicted distribution of shaking from the most recent Onsite and ElarmS solutions, respectively. (d) Posterior hyper‐robust prediction of ground motion from the CDM. The probabilities used in the PHRP PDF were obtained via a maximum‐likelihood estimate. (These are the probabilities that were computed from an LSQ fit between the observed and predicted waveform envelopes in Fig. 3 and shown in the previous pie charts.) (a) and (e) are the final observed ShakeMap for the Napa earthquake, with the P‐ and S‐wave positions plotted at 6 and 12 s after OT, respectively. (b)–(d) uses data and EEW algorithm reports from 6 s after OT. This is the time of the first ElarmS report, and Onsite has not yet reported. Note that the CDM immediately confirms the accuracy of the ElarmS report and produces a shaking prediction that is very close to the ElarmS solution and that accurately predicts the final observed shaking intensities. (f)–(h) Solution at 12 s after OT. This is when the first Onsite report is released. Note that the CDM correctly identifies that the ElarmS solution is preferable to the Onsite solution and creates a combined solution that favors the ElarmS shaking predictions and thus matches the observed shaking values.]()
![(a) Catalog locations (circles) and initial ElarmS‐2 solutions (stars) for all events with a single ElarmS‐2 alert. 67.5% of solutions are within 25 km of the catalog solution and 83.5% are within 50 km. (b) same as (a), except that the 23 events that were split into multiple ElarmS‐2 detections are removed (see text).The color version of this figure is available only in the electronic edition.]()
![Recent event dataset replay results for (a) Earthquake Alert Systems (ElarmS) v.2.0 (E2) and (b) E3 showing alerts for ANSS or ElarmS M≥3.0 events. On the maps, the following are plotted: yellow circles, ANSS locations; green circles, ElarmS location estimates; orange circles, missed events; and red circles, false events. The ShakeAlert reporting region is shown by the white boxy outline encompassing Washington, Oregon, and California, and extending into the Pacific Ocean.]()
![First thumbnail for: Earthquake Early Warning: ShakeAlert in the Pacifi...]()
![Second thumbnail for: Earthquake Early Warning: ShakeAlert in the Pacifi...]()
![Third thumbnail for: Earthquake Early Warning: ShakeAlert in the Pacifi...]()
![Same as Figure 5 for the 1 July 2015 Mw 8.2 ElarmS false alarm. (a)–(c) Snapshot of CDM performance at the time of the first ElarmS report (34 s after the OT reported by ElarmS). The CDM’s estimate of the algorithm probabilities immediately identifies that it is highly probable that this is not an earthquake and that, in turn, correctly pushes the most probable prediction to one of no shaking. As time progresses and more data become available, the probabilities even more strongly support this alert as a false alarm (d–f).]()
![Comparison of the ElarmS predicted magnitude and network determined ML. The ElarmS magnitude estimate is computed using equation (1). All event estimates fall within ±0.75 magnitude units of the ML.]()
![(a) E2 replay performance for the Testing and Certification group’s test suite showing alerts for ANSS or ElarmS M≥3.0 events. (b) E3 replay performance for the same dataset. Ⓔ Images from screenshots of the ElarmS review tool (available in the electronic supplement to this article).]()
![PDFs of expected PGA for the 1 July 2015 Mw 8.2 ElarmS false alarm at the four locations marked in Figure 6. The blue line is the PDF of expected ground motion based on the ElarmS source parameters. The magenta line is the PHRP PDF calculated by combining the ElarmS PDF and a prediction of zero ground motion, weighted by the probabilities given in the pie chart at top. Medians and 95% confidence bounds are given by the circles and brackets below the PDFs. The probability associated with the No Event algorithm, that is, the probability that the user should expect zero ground motion because an earthquake is not actually happening, is shown by the delta function to the left of the break in the scale. Because the probability of No Event is >95% at all times, the median and 95% confidence bounds of the CDM’s PDF are all identically zero‐predicted ground motion.]()
![Waveform comparisons for the 2014 Mw 6 South Napa earthquake (left) at 6 s after origin time (OT; the time of the first Earthquake Alarm Systems [ElarmS] report) and (right) 12 s after OT (the time of the first Onsite report). The observed envelopes of vertical acceleration are shown in black. The predictions from the most recent ElarmS report are shown in blue. Onsite predictions are shown in red. The black star is the location of the earthquake (38.22° N, 122.31° W), and the pink line shows the observed surface rupture. Yellow and red circles are the farthest reach of P and S waves after 6 (left) and 12 (right) s, assuming velocities of 6 and 3.5 km/s, respectively. The blue and red stars are the current estimated epicenters from ElarmS and Onsite, respectively. The probabilities for each algorithm calculated from these envelope comparisons are shown in the pie charts. Numbers in circles identify locations for which PDFs of expected ground motion are plotted in Figure 4.]()
![ElarmS review tool snapshot of the first alert of Mw 4.5 earthquake that occurred on 5 December 2016 at 18:55. Yellow circle marks the ANSS catalog location (latitude: 40.28, longitude: −124.39); green circle marks ElarmS calculated location. Seismic stations used for solving the event parameters are marked as green triangles, while other stations are marked as blue triangles. The blind zone is marked as a red circle and the propagating S-wave front in increments of 1 s are marked as white circles.]()
![Sum of squared errors (SSE) misfits between earthquake early warning (EEW) algorithm predictions and observations as a function of differing data availability. The predicted envelopes of acceleration from the first report from each EEW algorithm (Earthquake Alarm Systems [ElarmS], Virtual Seismologist) for the 2014 Mw 6.8 off Cape Mendocino earthquake are compared with the observed accelerations over a 5 min window, ending at the time given on the x axis. The P‐wave arrival times at the five stations nearest to the epicenter and the time of the first EEW report (issued by ElarmS) are marked.]()
![ElarmS v.3.0 (E3) Waveform Processor flowchart.]()
1-20 OF 169 RESULTS FOR
ElarmS
Results shown limited to content with bounding coordinates.
Follow your search
Access your saved searches in your account
Would you like to receive an alert when new items match your search?
1
Journal Article
An Earthquake Early Warning System for Northern Chile Based on ElarmS‐3 Available to Purchase
Journal: Seismological Research Letters
Publisher: Seismological Society of America
Published: 10 August 2022
Seismological Research Letters (2022) 93 (6): 3337–3347.
...–300 km depth) using ElarmS‐3, an earthquake early warning algorithm from the University of California, Berkeley. The alert time, or the time between when an earthquake alert is issued and the S ‐wave arrival at the location, is on average ∼24 s, and 96% of shallow and intermediate depth earthquakes (0...
FIGURES
Includes: Supplemental Content
Journal Article
Optimizing Earthquake Early Warning Performance: ElarmS‐3 Available to Purchase
Journal: Seismological Research Letters
Publisher: Seismological Society of America
Published: 16 January 2019
Seismological Research Letters (2019) 90 (2A): 727–743.
...Angela I. Chung; Ivan Henson; Richard M. Allen ABSTRACT The University of California Berkeley’s (UCB) Earthquake Alert Systems (ElarmS) is a network‐based earthquake early warning (EEW) algorithm that was one of the original algorithms developed for the U.S. west‐coast‐wide ShakeAlert EEW system...
FIGURES
Includes: Supplemental Content
Journal Article
Implementing the ElarmS Earthquake Early Warning Algorithm on the Israeli Seismic Network Available to Purchase
Publisher: Seismological Society of America
Published: 23 August 2016
Bulletin of the Seismological Society of America (2016) 106 (5): 2332–2344.
... phase, we demonstrate implementation of one of its three algorithms, ElarmS, to the Israel region. We provide new tools and approaches for implementing and assessing ElarmS outside of California. The main challenges of this research are to identify, verify, and adjust the embedded location‐dependent...
FIGURES
Journal Article
Designing a Network‐Based Earthquake Early Warning Algorithm for California: ElarmS‐2 Available to Purchase
Publisher: Seismological Society of America
Published: 24 December 2013
Bulletin of the Seismological Society of America (2014) 104 (1): 162–173.
... algorithms are being tested, one of which is the network‐based Earthquake Alarm Systems (ElarmS) EEW system. Over the last three years, the ElarmS algorithms have undergone a large‐scale reassessment and have been recoded to solve technological and methodological challenges. The improved algorithms...
FIGURES
Journal Article
Testing ElarmS in Japan Available to Purchase
Journal: Seismological Research Letters
Publisher: Seismological Society of America
Published: 01 September 2009
Seismological Research Letters (2009) 80 (5): 727–739.
...Holly M. Brown; Richard M. Allen; Veronica F. Grasso © 2009 by the Seismological Society of America 2009 ElarmS performs each of these scaling calculations independently, resulting in one τ p max -based magnitude estimate and one P d -based magnitude estimate each second. The two...
FIGURES
Journal Article
The Potential for Earthquake Early Warning in Italy Using ElarmS Available to Purchase
Publisher: Seismological Society of America
Published: 01 February 2008
Bulletin of the Seismological Society of America (2008) 98 (1): 495–503.
... is the rapid detection of an event in progress, assessment of the hazard it poses, and transmission of a warning ahead of any significant ground motion. We explore the potential for using the INSN real-time network for the purpose of earthquake early warning. We run the ElarmS early warning methodology off...
FIGURES
Image
Same as Figure 3 for the 1 July 2015 M w 8.2 ElarmS false alarm ... Available to Purchase
in Combining Multiple Earthquake Models in Real Time for Earthquake Early Warning
> Bulletin of the Seismological Society of America
Published: 13 June 2017
Figure 6. Same as Figure 3 for the 1 July 2015 M w 8.2 ElarmS false alarm at the time of the first ElarmS report (34 s after the OT reported by ElarmS). The P ‐ and S ‐wave positions are drawn relative to the location and OT of the ElarmS false earthquake source. ElarmS predicts
Image
Illustration of the new split event check criteria. Each circle represents ... Available to Purchase
in Earthquake Early Warning: ShakeAlert in the Pacific Northwest
> Bulletin of the Seismological Society of America
Published: 05 July 2016
Figure 9. Illustration of the new split event check criteria. Each circle represents a subsequent ElarmS‐2 solution compared to the first ElarmS‐2 solution for a split earthquake. The horizontal axis is the difference in estimated origin time, and the vertical axis shows the horizontal distance
Image
(a) Final observed peak horizontal shaking intensity for the 2014 M w ... Available to Purchase
in Combining Multiple Earthquake Models in Real Time for Earthquake Early Warning
> Bulletin of the Seismological Society of America
Published: 13 June 2017
of shaking from the most recent Onsite and ElarmS solutions, respectively. (d) Posterior hyper‐robust prediction of ground motion from the CDM. The probabilities used in the PHRP PDF were obtained via a maximum‐likelihood estimate. (These are the probabilities that were computed from an LSQ fit between
Image
(a) Catalog locations (circles) and initial ElarmS‐2 solutions (stars) for ... Available to Purchase
in Earthquake Early Warning: ShakeAlert in the Pacific Northwest
> Bulletin of the Seismological Society of America
Published: 05 July 2016
Figure 10. (a) Catalog locations (circles) and initial ElarmS‐2 solutions (stars) for all events with a single ElarmS‐2 alert. 67.5% of solutions are within 25 km of the catalog solution and 83.5% are within 50 km. (b) same as (a), except that the 23 events that were split into multiple ElarmS‐2
Image
Recent event dataset replay results for (a) Earthquake Alert Systems (Elarm... Available to Purchase
Published: 16 January 2019
Figure 6. Recent event dataset replay results for (a) Earthquake Alert Systems (ElarmS) v.2.0 (E2) and (b) E3 showing alerts for ANSS or ElarmS M ≥ 3.0 events. On the maps, the following are plotted: yellow circles, ANSS locations; green circles, ElarmS location estimates; orange circles
Journal Article
Earthquake Early Warning: ShakeAlert in the Pacific Northwest Available to Purchase
Publisher: Seismological Society of America
Published: 05 July 2016
Bulletin of the Seismological Society of America (2016) 106 (4): 1875–1886.
...Figure 9. Illustration of the new split event check criteria. Each circle represents a subsequent ElarmS‐2 solution compared to the first ElarmS‐2 solution for a split earthquake. The horizontal axis is the difference in estimated origin time, and the vertical axis shows the horizontal distance...
FIGURES
Includes: Supplemental Content
Image
Same as Figure 5 for the 1 July 2015 M w 8.2 ElarmS false alarm.... Available to Purchase
in Combining Multiple Earthquake Models in Real Time for Earthquake Early Warning
> Bulletin of the Seismological Society of America
Published: 13 June 2017
Figure 8. Same as Figure 5 for the 1 July 2015 M w 8.2 ElarmS false alarm. (a)–(c) Snapshot of CDM performance at the time of the first ElarmS report (34 s after the OT reported by ElarmS). The CDM’s estimate of the algorithm probabilities immediately identifies that it is highly
Image
Comparison of the ElarmS predicted magnitude and network determined M L .... Available to Purchase
in The Potential for Earthquake Early Warning in Italy Using ElarmS
> Bulletin of the Seismological Society of America
Published: 01 February 2008
Figure 5. Comparison of the ElarmS predicted magnitude and network determined M L . The ElarmS magnitude estimate is computed using equation (1) . All event estimates fall within ±0.75 magnitude units of the M L .
Image
(a) E2 replay performance for the Testing and Certification group’s test su... Available to Purchase
Published: 16 January 2019
Figure 8. (a) E2 replay performance for the Testing and Certification group’s test suite showing alerts for ANSS or ElarmS M ≥ 3.0 events. (b) E3 replay performance for the same dataset. Ⓔ Images from screenshots of the ElarmS review tool (available in the electronic supplement
Image
PDFs of expected PGA for the 1 July 2015 M w 8.2 ElarmS false alar... Available to Purchase
in Combining Multiple Earthquake Models in Real Time for Earthquake Early Warning
> Bulletin of the Seismological Society of America
Published: 13 June 2017
Figure 7. PDFs of expected PGA for the 1 July 2015 M w 8.2 ElarmS false alarm at the four locations marked in Figure 6 . The blue line is the PDF of expected ground motion based on the ElarmS source parameters. The magenta line is the PHRP PDF calculated by combining the ElarmS PDF
Image
![Waveform comparisons for the 2014 Mw 6 South Napa earthquake (left) at 6 s after origin time (OT; the time of the first Earthquake Alarm Systems [ElarmS] report) and (right) 12 s after OT (the time of the first Onsite report). The observed envelopes of vertical acceleration are shown in black. The predictions from the most recent ElarmS report are shown in blue. Onsite predictions are shown in red. The black star is the location of the earthquake (38.22° N, 122.31° W), and the pink line shows the observed surface rupture. Yellow and red circles are the farthest reach of P and S waves after 6 (left) and 12 (right) s, assuming velocities of 6 and 3.5 km/s, respectively. The blue and red stars are the current estimated epicenters from ElarmS and Onsite, respectively. The probabilities for each algorithm calculated from these envelope comparisons are shown in the pie charts. Numbers in circles identify locations for which PDFs of expected ground motion are plotted in Figure 4.](https://gsw.silverchair-cdn.com/gsw/Content_public/Journal/bssa/107/4/10.1785_0120160331/2/s_0120160331fig3.png?Expires=2147483647&Signature=01zNp4gXM59lbg0yff9CJNfXr6HbD64biLv4KdOuBogENc9sk5Hn6Een97WLKGSk-qnMrNX-6Oz5rUzxnfrg0EMz0O~B3GtTo8EtOFzncq5lcM3V9COBApsA4Erk3xRBB5SOIe8sFn3NDQVaMSD7wPjhBphlFowGj33Wn1pUVyuHfr-1JKpvGA~rXfoqqMB9wlqn7baWdVPjZS2wy64wD6buz-E5lwqSImWpLKd1RFYRdlOpl6PL78d8rkoEdUzPSC~oXSunGf2TQGnwNdD620kXLdJ1q2oUjJZNHOPrfNbf4JwRYvUEftsjh-KhTjFgQAxc5hYQfRLcURI1rv9~6g__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
Waveform comparisons for the 2014 M w 6 South Napa earthquake (lef... Available to Purchase
in Combining Multiple Earthquake Models in Real Time for Earthquake Early Warning
> Bulletin of the Seismological Society of America
Published: 13 June 2017
Figure 3. Waveform comparisons for the 2014 M w 6 South Napa earthquake (left) at 6 s after origin time (OT; the time of the first Earthquake Alarm Systems [ElarmS] report) and (right) 12 s after OT (the time of the first Onsite report). The observed envelopes of vertical acceleration
Image
ElarmS review tool snapshot of the first alert of Mw 4.5 earthquake that oc... Available to Purchase
in MEMS Accelerometer Mini-Array (MAMA): A Low-Cost Implementation for Earthquake Early Warning Enhancement
> Earthquake Spectra
Published: 01 February 2019
Figure 9. ElarmS review tool snapshot of the first alert of Mw 4.5 earthquake that occurred on 5 December 2016 at 18:55. Yellow circle marks the ANSS catalog location (latitude: 40.28, longitude: −124.39); green circle marks ElarmS calculated location. Seismic stations used for solving the event
Image
![Sum of squared errors (SSE) misfits between earthquake early warning (EEW) algorithm predictions and observations as a function of differing data availability. The predicted envelopes of acceleration from the first report from each EEW algorithm (Earthquake Alarm Systems [ElarmS], Virtual Seismologist) for the 2014 Mw 6.8 off Cape Mendocino earthquake are compared with the observed accelerations over a 5 min window, ending at the time given on the x axis. The P‐wave arrival times at the five stations nearest to the epicenter and the time of the first EEW report (issued by ElarmS) are marked.](https://gsw.silverchair-cdn.com/gsw/Content_public/Journal/bssa/107/4/10.1785_0120160331/2/s_0120160331figA1.png?Expires=2147483647&Signature=CIRZf7GAXa3hde7wvSXSO4VQ~BdbT5-2uSrvHqAcrnjv4-cI~7H97WpjdQPsWrGRGOauksUTvkCpHto5XKL16wXiHetHR3J2uGJbqGlCSLpofAPn~kXwvGx9eLGGItimhWWtuaSC3-7dMbLCWTszLDe4B-3by6ygd~d~JajTX-zyvvt2WKmaVsXJKPEHEAUgy1B8SsD9HsaZoYFPK0BF91emPxg83tU4VSRg-su7JqSjAOjL5j1772HGU5qDRTob-BhiL3ZV1UlC8zJRfcWF9VzBn~~6N4fz8VCUeI7trMZskJ~PJzUxSdVitFJ7g-lupb~XA-KtD6i3RN3sV-CkMg__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
Sum of squared errors (SSE) misfits between earthquake early warning (EEW) ... Available to Purchase
in Combining Multiple Earthquake Models in Real Time for Earthquake Early Warning
> Bulletin of the Seismological Society of America
Published: 13 June 2017
Figure A1. Sum of squared errors (SSE) misfits between earthquake early warning (EEW) algorithm predictions and observations as a function of differing data availability. The predicted envelopes of acceleration from the first report from each EEW algorithm (Earthquake Alarm Systems [ElarmS
Image
ElarmS v.3.0 (E3) Waveform Processor flowchart. Available to Purchase
Published: 16 January 2019
Figure 4. ElarmS v.3.0 (E3) Waveform Processor flowchart.
1
