Location performance of the Alaska regional seismic network: an evaluation by the SNES method

Seismic networks are powerful tools for understanding the state of seismo-tectonic processes taking place in a region. Their numerous applications, from monitoring seismicity to characterizing seismogenic volumes, make seismic networks essential tools for the seismic risk assessment. Appropriately structured seismic network may also be a valuable tool for the study of deep geological structures through seismic tomography. The ability to detect small and medium sized events requires a seismic network with sufficient number of low noise stations that are optimally distributed. It is, therefore, important to assess existing capabilities of a seismic network, to identify seismic areas that are not adequately covered, and to further ascertain measures for the network improvement. Alaska is the most seismically active region of the United States. Seismicity is associated with the subduction of the P acific plate beneath the North American plate, with the transform boundary in the southeast Alaska, and with numerous crustal faults throughout the State. Regional seismicity in Alaska is monitored by the Alaska Earthquake Information Center (AEIC) utilizing combined regional seismic network that comprises over 400 seismic sites. In this poster we will evaluate earthquake location performance of the Alaska regional seismic network though SNES (Seismic Networks Evaluation through Simulation) method. This method analyzes noise levels of existing stations, location errors, and velocity uncertainties and produces certain metrics that allow to asses capabilities of an existing network. In particular, through SNES we have identified high and low seismic noise areas of Alaska seismic network. Through statistical analysis of P and S residual times we have assessed validity of velocity models used by AEIC in their earthquake location routines and produced empirical formulas that link travel time residual time variance to the hypocentral distance. Finally, from analysis of produced SNES maps, we will identify regions in Alaska where it may be opportune to improve the existing seismic network

Alaska Earthquake Center Quarterly Technical Report October-December 2022

This series of technical quarterly reports from the Alaska Earthquake Center (AEC) includes detailed summaries and updates on Alaska seismicity, the AEC seismic network and stations, field work, our social media presence, and lists publications and presentations by AEC staff. Multiple AEC staff members contribute to this report. It is issued in the following month after the completion of each quarter Q1: January-March, Q2: April-June, Q3: July-September, and Q4: October-December. The first report was published for January-March, 2021.1. Introduction 2. Seismicity 3. Field network 4. Data Quality assurance 4.1 Seismic data 4.2 Environmental data 5. Real-time earthquake detection system 6. Computer systems 6.1 Computer resources 6.2 Waveform storage 6.3 Metadata 6.4 Software development 7. Fieldwork 8. Social media and outreach 8.1. Website 8.2. Twitter 8.3. Facebook Page 9. Publications and presentations 9.1. Publications 9.2. Public Presentations 9.3. Lunch Seminar Talks 10. References Appendix A: Data availability for broadband stations from the AK network. Appendix B: Gaps for broadband stations from the AK network

2022 Alaska Seismicity Summary

The Alaska Earthquake Center reported 47,045 seismic events in Alaska and neighboring regions in 2022. The largest earthquake was a magnitude 6.8 event that occurred on January 11 in the Fox Islands region of the Aleutian Islands. Other active spots include two M6.3 earthquakes in the Rat Islands on June 4 and December 14, both of which were followed by moderate aftershock sequences. A magnitude 5.4 earthquake was recorded in an unusual location in the Bering Sea, east of St. George Island, on July 4. The two largest earthquakes in mainland Alaska, both magnitude 5.2, occurred in the Yakutat Bay region on January 8 and in central Alaska on February 6. We continued to monitor ongoing activity within the 2018 M7.1 Anchorage, 2018 M6.4 Kaktovik, 2018 M7.9 Offshore Kodiak, 2020 M7.6 Simeonof, and 2021 M8.2 Chignik aftershock sequences, the Purcell Mountains earthquake swarm, and the Wright Glacier cluster northeast of Juneau. All aftershock sequences continued to slow down compared to the previous years.1. Abstract 2. Introduction 3. Notable earthquakes and sequences of 2022 3.1. January 11 M6.8 and M6.6 and January 22 M6.2 earthquakes in Fox Islands 3.2. June 4 M6.3 and December 14 M6.3 earthquakes in Rat Islands 3.2. July 4 M5.4 in Pribilof Islands 4. Ongoing aftershock sequences and swarms 4.1. 2021 M8.2 Chignik aftershock sequence 4.2. 2020 M7.8 Simeonof aftershock sequence 4.3. 2018 M7.1 Anchorage aftershock sequence 4.4. 2018 M6.4 Kaktovik aftershock sequence 4.5. 2018 M7.9 Offshore Kodiak aftershock sequence 4.6. Purcell Mountains earthquake swarm 5. Glacial seismicity and Wright Glacier cluster 6. Acknowledgments 7. Reference

Alaska Earthquake Center Quarterly Technical Report January-March 2022

This series of technical quarterly reports from the Alaska Earthquake Center (AEC) includes detailed summaries and updates on Alaska seismicity, the AEC seismic network and stations, field work, our social media presence, and lists publications and presentations by AEC staff. Multiple AEC staff members contribute to this report. It is issued in the following month after the completion of each quarter Q1: January-March, Q2: April-June, Q3: July-September, and Q4: October-December. First report was published for January-March, 2021.Contents 1 Introduction 2 Seismicity 2 Field network 9 Data Quality assurance 11 4.1 Seismic data 11 4.2 Environmental data 12 Real-time earthquake detection system 13 Computer systems 17 6.1 Computer resources 17 6.2 Waveform storage 17 6.3 Metadata 18 6.4 Software development 18 Fieldwork 18 Social media and outreach 19 8.1. Website 19 8.2. Twitter 20 8.3. Facebook (Page) 22 Publications and presentations 24 9.1. Publications 24 9.2. Public Presentations 25 9.3. Lunch Seminar Talks 25 References 26 Appendix A: Data availability for broadband stations from the AK network. 27 Appendix B: Gaps for broadband stations from the AK network. 3

Alaska Earthquake Center Quarterly Technical Report July-September 2021

This series of technical quarterly reports from the Alaska Earthquake Center (AEC) includes detailed summaries and updates on Alaska seismicity, the AEC seismic network and stations, field work, our social media presence, and lists publications and presentations by AEC staff. Multiple AEC staff members contributed to this report. It is issued in the following month after the completion of each quarter Q1: January-March, Q2: April-June, Q3: July-September, and Q4: October-December.1. Introduction 2. Seismicity 3. Field network 4. Data Quality assurance 5. Real-time earthquake detection system 6. Computer systems 6.1 Computer resources 6.2 Waveform storage 6.3 Metadata 6.4 Software development 7. Fieldwork 8. Social media and outreach 8.1. Website 8.2. Twitter 8.3. Facebook (Page) 8.4. Facebook (Group) 9. Publications and presentations 9.1. Publications 9.2. Public Presentations 9.3. Lunch Seminar Talks 10. References Appendix A: Data availability for broadband stations from the AK network. Appendix B: Gaps for broadband stations from the AK network

Alaska Earthquake Center Quarterly Technical Report January-March 2021

This is the first in a series of technical quarterly reports from the Alaska Earthquake Center (AEC). It includes detailed summaries and updates on Alaska seismicity, the AEC seismic network and stations, field work, our social media presence, and lists publications and presentations by AEC staff. Multiple AEC staff members contributed to this report. It is issued in the following month after the completion of each quarter Q1: January-March, Q2: April-June, Q3: July-September, and Q4: October-December.1. Introduction 2. Seismicity 3. Field network 4. Data Quality assurance 5. Real-time earthquake detection system 6. Computer systems 6.1 Computer resources 6.2 Waveform storage 6.3 Metadata 6.4 Software development 7. Fieldwork 8. Social media and outreach 8.1. Website 8.2. Twitter 8.3. Facebook (Page) 8.4. Facebook (Group): 9. Publications and presentations 9.1. Publications 9.2. Public Presentations 9.3. Brown Bag Talks 10. References Appendix A: Data availability for broadband stations from AK network. Appendix B: Gaps for broadband stations from AK network

Alaska Earthquake Center Quarterly Technical Report January-March 2023

This series of technical quarterly reports from the Alaska Earthquake Center (AEC) includes detailed summaries and updates on Alaska seismicity, the AEC seismic network and stations, field work, our social media presence, and lists publications and presentations by AEC staff. Multiple AEC staff members contribute to this report. It is issued in the following month after the completion of each quarter Q1: January-March, Q2: April-June, Q3: July-September, and Q4: October-December. The first report was published for January-March, 2021.1. Introduction 2. Seismicity 3. Field network 4. Data Quality assurance 4.1 Seismic data 4.2 Environmental data 5. Real-time earthquake detection system 6. Computer systems 6.1 Computer resources 6.2 Waveform storage 6.3 Metadata 6.4 Software development 7. Fieldwork 8. Social media and outreach 8.1 Website 8.2 Twitter 8.3 Facebook Page 9. Publications and presentations 9.1 Publications 9.2 Public Presentations 9.3 Lunch Seminar Talks 10. References Appendix A: Data availability for broadband stations from the AK network. Appendix B: Gaps for broadband stations from the AK network

Alaska Earthquake Center Quarterly Technical Report April-June 2021

This series of technical quarterly reports from the Alaska Earthquake Center (AEC) includes detailed summaries and updates on Alaska seismicity, the AEC seismic network and stations, field work, our social media presence, and lists publications and presentations by AEC staff. Multiple AEC staff members contributed to this report. It is issued in the following month after the completion of each quarter Q1: January-March, Q2: April-June, Q3: July-September, and Q4: October-December.1.Introduction 2. Seismicity 3. Field network 4. Data Quality assurance 5. Real-time earthquake detection system 6. Computer systems 6.1. Computer resources 6.2. Waveform storage 6.3. Metadata 6.4. Software development 7. Fieldwork 8. Social media and outreach 8.1. Website 8.2. Twitter 8.3. Facebook (Page) 8.4. Facebook (Group) 9. Publications and presentations 9.1. Publications 9.2. Public Presentations 9.3. Lunch Seminar Talks 10. References Appendix A: Data availability for broadband stations from AK network. Appendix B: Gaps for broadband stations from AK network

Alaska Earthquake Center Quarterly Technical Report July-September 2022

This series of technical quarterly reports from the Alaska Earthquake Center (AEC) includes detailed summaries and updates on Alaska seismicity, the AEC seismic network and stations, field work, our social media presence, and lists publications and presentations by AEC staff. Multiple AEC staff members contribute to this report. It is issued in the following month after the completion of each quarter Q1: January-March, Q2: April-June, Q3: July-September, and Q4: October-December. The first report was published for January-March, 2021.1 Introduction 2 Seismicity 3 Field network 4 Data Quality assurance 4.1 Seismic data 4.2 Environmental data 5 Real-time earthquake detection system 6 Computer systems 6.1 Computer resources 6.2 Waveform storage 6.3 Metadata 6.4 Software development 7 Fieldwork 8 Social media and outreach 8.1. Website 8.2. Twitter 8.3. Facebook Page 8.4 K-12 and Community Outreach 9 Publications and presentations 9.1. Publications 9.2. Public Presentations 9.3. Lunch Seminar Talks 10 References Appendix A: Data availability for broadband stations from the AK network. Appendix B: Gaps for broadband stations from the AK network

2021 Alaska Seismicity Summary

The Alaska Earthquake Center reported 49,120 seismic events in Alaska and neighboring regions in 2021. The largest earthquake was a magnitude 8.2 event that occurred on July 29 southwest of Kodiak Island. It was followed by about 1,300 aftershocks including two magnitude 6.9 events on August 14 and October 11. Other active spots include sequences near Harding Lake in Interior Alaska in July-September and near Yakutat Bay in September. The largest earthquake in mainland Alaska was the M6.1 Chickaloon Earthquake on May 31. We continued to monitor ongoing activity within the 2018 M7.1 Anchorage, 2018 M6.4 Kaktovik, and 2018 M7.9 Offshore Kodiak aftershock sequences, the Purcell Mountains earthquake swarm, and the Wright Glacier cluster northeast of Juneau.1. Abstract 2. Introduction 3. Notable earthquakes and sequences of 2021 3.1. January 3 and September 24 M6.1 earthquakes in Andreanof Islands 3.2. May 31 M6.1 Chickaloon Earthquake 3.3. July 29 M8.2 Chignik Earthquake 3.4. July 23 M4.7 and September 14 M4.9 Harding Lake earthquakes 3.5. September 5-6 M4.0 and M4.1 Yakutat earthquakes 4. Ongoing aftershock sequences and swarms 4.1. 2020 M7.8 Simeonof aftershock sequence 4.2. 2018 M7.1 Anchorage aftershock sequence 4.3. 2018 M6.4 Kaktovik aftershock sequence 4.4. 2018 M7.9 Offshore Kodiak aftershock sequence 4.5. Purcell Mountains earthquake swarm 4.6. Northeast Brooks Range earthquake swarm 5. Glacial seismicity and Wright Glacier cluster 6. Acknowledgments 7. Reference