The Alaska Amphibious Community Seismic Experiment

Abstract

The Alaska Amphibious Community Seismic Experiment (AACSE) is a shoreline-crossing passive- and active-source seismic experiment that took place from May 2018 through August 2019 along an ∼700 km long section of the Aleutian subduction zone spanning Kodiak Island and the Alaska Peninsula. The experiment featured 105 broadband seismometers; 30 were deployed onshore, and 75 were deployed offshore in Ocean Bottom Seismometer (OBS) packages. Additional strong-motion instruments were also deployed at six onshore seismic sites. Offshore OBS stretched from the outer rise across the trench to the shelf. OBSs in shallow water (<262 m depth) were deployed with a trawl-resistant shield, and deeper OBSs were unshielded. Additionally, a number of OBS-mounted strong-motion instruments, differential and absolute pressure gauges, hydrophones, and temperature and salinity sensors were deployed. OBSs were deployed on two cruises of the R/V Sikuliaq in May and July 2018 and retrieved on two cruises aboard the R/V Sikuliaq and R/V Langseth in August–September 2019. A complementary 398-instrument nodal seismometer array was deployed on Kodiak Island for four weeks in May–June 2019, and an active-source seismic survey on the R/V Langseth was arranged in June 2019 to shoot into the AACSE broadband network and the nodes. Additional underway data from cruises include seafloor bathymetry and sub-bottom profiles, with extra data collected near the rupture zone of the 2018 Mw 7.9 offshore-Kodiak earthquake. The AACSE network was deployed simultaneously with the EarthScope Transportable Array (TA) in Alaska, effectively densifying and extending the TA offshore in the region of the Alaska Peninsula. AACSE is a community experiment, and all data were made available publicly as soon as feasible in appropriate repositories.

Amphibious Shear Wave Structure Beneath the Alaska‐Aleutian Subduction Zone From Ambient Noise Tomography

“…Barcheck et al. (2020) provided a timing correction list for six stations (KT06, KT09, EP23, LT02, LT08, LT11, colored in green in Figure 1) which suffer from large and long period timing errors. Continuous daily records from those stations are corrected according to the clock correction list.…”

“…The very first step of data pre-processing is to correct the timing of daily seismic records. Barcheck et al (2020) provided a timing correction list for six stations (KT06, KT09, EP23, LT02, LT08, LT11, colored FENG 10.1029/2020GC009438 4 of 18 A map illustrating all the seismic stations used in this study. The stations are plotted in six different colors.…”

“…The Alaska Amphibious Community Seismic Experiment (AACSE) project (Barcheck et al., 2020), which deployed an array of 75 broadband ocean seismometers (OBSs) and 30 onshore broadband seismometers for 15 months, partially fills the offshore seismic data coverage gap across the Alaska‐Aleutian subduction zone. The array presents an unprecedented opportunity to help us better image the seismic structure beneath the subduction zone in order to better understand the plate attributes and associated seismicity variation.…”

“…The red, green, cyan, black, and yellow ones are located inside the study region. Red, green, cyan, and black triangles represent AACSE array: green ones are the stations with large and long period timing error (Barcheck et al., 2020) and the cyan station is the station XO.WD61 which is identified as anomalous station in intermediate to long period (∼20–50 s) tomographic results. The black ones are the stations without data.…”

Improving Detectability of Seafloor Deformation From Bottom Pressure Observations Using Numerical Ocean Models

“…Figure 9 shows the result at the Aleutian Trench in which the AASCE project (Barcheck et al, 2020) was carried out. Time series of 10 stations from June 2018 to March 2019 were used.…”