D. S. Neuhauser

Designing a Network‐Based Earthquake Early Warning Algorithm for California: ElarmS‐2

The California Integrated Seismic Network (CISN) is developing an earthquake early warning (EEW) demonstration system for the state of California. Within this CISN ShakeAlert project, three 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 in the new production-grade version of the ElarmS version 2 (referred to as ElarmS-2 or E2) code maximize the current seismic networks configuration, hardware, and software per- formance capabilities, improving both the speed of the early warning processing and the accuracy of the warnings. E2 is designed as a modular code and consists of a new event monitor module with an improved associator that allows for more rapid association with fewer triggers, while also adding several new alert filter checks that help minimize false alarms. Here, we outline the methodology and summarize the performance of this new online real-time system. The online performance from 2 October 2012 to 15 February 2013 shows, on average, ElarmS currently issues an alert 8:68 � 3:73 sa fter the first P-wave detection for all events across California. This time is reduced by 2 s in regions with dense station instrumentation. Standard deviations of magnitude, origin time are 0.4 magnitude units, 1.2 s, and the median location errors is 3.8 km. E2 successfully detected 26 of 29 earthquakes (MANSS >3:5) across California, while issuing two false alarms. E2 is now delivering alerts to ShakeAlert, which in turn distributes warnings to test users.

MOISE: A pilot experiment towards long term sea-floor geophysical observatories

We describe the scientific purposes and experimental set-up of an international deployment of a 3 component broadband seismometer package on the ocean floor in Monterey Bay which took place during the summer of 1997. Highlights of this experiment were the installation, performed using a remotely operated vehicle (ROV), the underwater connection of the different components of the package, and the successful retrieval of 3 months of broadband seismic and auxiliary data. Examples of recordings of teleseisms and regional earthquakes are presented and the background noise characteristics are discussed, in comparison with those of near-by broadband land sites, current-meter data from the vicinity of the ocean bottom package, as well as pressure data from deeper ocean sites.

CISN ShakeAlert: An Earthquake Early Warning Demonstration System for California

To demonstrate the feasibility of earthquake early warning (EEW) in California, we have developed and implemented the CISN ShakeAlert demonstration system. A Decision Module combines estimates and uncertainties determined by three algorithms implemented in parallel, \(\tau _\mathrm{{c}}-\mathrm{{P}}_\mathrm{{d}}\) Onsite, Virtual Seismologist, and ElarmS, to calculate and report at a given time the most probable earthquake magnitude and location, as well as the likelihood of correct alarm. A User Display receives the alert messages in real-time, calculates the expected local shaking intensity, and displays the information on a map. Currently, CISN ShakeAlert is being tested by \(\sim \)70 individuals and test users from industries and emergency response organizations in California. During the next 3 years we plan to expand this demonstration warning system to the entire US West Coast.

Accessing northern California earthquake data via Internet

The Northern California Earthquake Data Center (NCEDC) provides easy access to central and northern California digital earthquake data. It is located at the University of California, Berkeley, and is operated jointly with the U.S. Geological Survey (USGS) in Menlo Park, Calif., and funded by the University of California and the National Earthquake Hazard Reduction Program. It has been accessible to users in the scientific community through Internet since mid-1992. The data center provides an on-line archive for parametric and waveform data from two regional networks: the Northern California Seismic Network (NCSN) operated by the USGS and the Berkeley Digital Seismic Network (BDSN) operated by the Seismographic Station at the University of California, Berkeley.

77 - The Rapid Earthquake Data Integration Project

This chapter focuses on the rapid earthquake data integration project. Interest in rapid access to earthquake information has grown enormously in the last few years. In addition to satisfying inquiries from the public and the media, rapid notification programs provide valuable information for earthquake disaster response. Recognizing the importance of this information for seismic hazard mitigation, efforts to design and implement systems to provide earthquake parameters in a timely manner have expanded over the last 10 years at both the regional and the national level. Similar to most automated earthquake processing systems, rapid earthquake data integration (REDI) operations can be divided into two major elements: event identification and event processing. The event identification element includes operations such as phase picking, event association, and event selection. The event processing element is separated into several stages, with each earthquake assessed for a particular type of processing based on its location and size. The Rapid Earthquake Data Integration System has been developed for the automated estimation of earthquake parameters using data from a sparse, broadband network. The system is designed on the basis of a staged hierarchy of processing, with the goal of providing control of the type and number of processes running at any time. The current processing capabilities include the determination of local and energy magnitude, peak ground motions, and the seismic moment tensor.