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At least 37 records · Page 2Linked to original sources
USGS2000

The 1999 Southern California Seismic Network bulletin

The Pasadena office of the U.S. Geological Survey (USGS), together with the Caltech Seismological Laboratory, operates a network of more than 350 remote seismometers in southern California called the S outhern C alifornia S eismic N etwork (SCSN). SCSN is part of TriNet, a cooperative project between the USGS, Caltech, and the California Division of Mines and Geology (CDMG). The TriNet project is halfway completed and is upgrading the existing network to digital, adding new stations, and developing real-time and earthquake-alert capabilities. Signals from the SCSN sites are telemetered to a central processing location at the Caltech Seismological Lab in Pasadena. Computers that detect and record thousands of earthquakes each year continuously monitor these signals. Phase arrival times for these events are picked by analysts and are archived along with digital seismograms. Data acquisition, processing, and archiving are achieved using the Caltech/USGS Seismic Processing (CUSP) system ( Dollar, 1989 ). These data have been compiled into the SCSN Catalog of Earthquakes, a list beginning in 1932 that currently contains more than 356,300 events. Waveform, phase, and catalog data are archived by the Southern California Earthquake Center Data Center (SCEC_DC). This data set is critical to the evaluation of earthquake hazards in California and to the advancement of geoscience as a whole.

California↗
USGS1982

Test and calibration of the Digital World-Wide Standardized Seismograph

During the past decade there has been steady progress in the modernization of the global seismograph network operated by the U.S. Geological Survey (USGS). The World-Wide Standardized Seismograph Network (WWSSN) has been augmented by new stations with advanced instrumentation, including the Seismic Research Observatories (SRO) and the modified High-Gain Long-Period (ASRO) stations. One goal in the modernization effort has been to improve signal resolution in the long-period band. A second goal has been to generate a global digital data base to support contemporary computer-based analysis and research. In 1976, a Panel on Seismograph Networks was established by the Committee on Seismology of the National Academy of Sciences to review progress in network seismology and recommend actions that would lead to an improved global data base for seismology. One recommendation in the Panel report (Engdahl, 1977) called for upgrading selected WWSSN stations by the installation of digital recorders. This was viewed as an economical way of expanding the digital network, which had proven itself to be a very promising new tool for earthquake and explosion research. Funds for the development and assembly of 15 digital recorders were provided to the USGS by the Defense Advanced Research Projects Agency and an ad Inoc panel of scientists was convened by the Committee on Seismology to advise the USGS on the selection of stations to be upgraded and on data recording requirements, A total of 19 digital World-Wide Standardized Seismograph (DWWSS) systems will be operational when all are installed. The additional systems were made available through purchase by the USGS and other organizations; for example, the University of Bergen purchased and installed a DWWSS-type recorder and agreed to furnish the USGS with the data. A list of operational and planned DWWSS network stations is given in Table 1.1. As one might expect, the digital recorder turned out to be somewhat more sophisticated than the original concept. It was decided to record three components of long-period data continuously, three components of intermediateperiod data in an event mode, and the vertical-component short-period data in and event mode (with the capability of adding short-period horizontal channels in the future). Special amplifiers were developed for use with the WWSS seismometers, and a 16-bit fixed-point analog-to-digital converter was chosen to provide increased resolution (as opposed to a 16-bit gain-ranged encoder). The microprocessor-based digital recording systems were developed and assembled at the USGS Albuquerque Seismological Laboratory (ASL) and ASL-based technicians began installation at WWSSN stations in 1980. The current and proposed locations of the DWWSSN stations, together with other stations in the Global Digital Seismograph Network (GDSN), are shown on the map in Figure 1.1. A system was operated at Albuquerque for about 18 months, serving as a test bed for evaluation studies. Although the network hardware has been available for some time, the installation of the DWWSSN has proceeded slowly. The National Science Foundation supported installation of six stations and the USGS is funding installation of most of the others; however, the network completion date is conjectural because of funding uncertainties. The DWWSSN stations are supported with supplies and technical assistance from ASL (subject to availability of funds). Data recorded on magnetic tapes are mailed to ASL where they are reviewed for quality, then merged with other GDSN station data on the network-day tapes. Hoffman (1980) provides a description of the network-day tape format. Zirbes and Buland (1981) have developed and published user software for reading and interpreting the day tapes. This report will serve several purposes. One is to provide nominal system transfer functions and calibration information that are needed in the analysis of DWWSSN data. A second purpose is to report on an evaluation of operating characteristics (calibration stability, noise levels, and linearity) that may limit the usefulness of the data and to determine if modifications may be needed to improve the data. It is not an exhaustive study in this respect. We continue to depend mostly on data user feedback to point out deficiencies and we solicit comments whenever anomalies are observed in the data.

Open-File Report↗
USGS2017

Reexamination of the magnitudes for the 1906 and 1922 Chilean earthquakes using Japanese tsunami amplitudes: Implications for source depth constraints

Far-field tsunami records from the Japanese tide gauge network allow the reexamination of the moment magnitudes ( M w ) for the 1906 and 1922 Chilean earthquakes, which to date rely on limited information mainly from seismological observations alone. Tide gauges along the Japanese coast provide extensive records of tsunamis triggered by six great ( M w >8) Chilean earthquakes with instrumentally determined moment magnitudes. These tsunami records are used to explore the dependence of tsunami amplitudes in Japan on the parent earthquake magnitude of Chilean origin. Using the resulting regression parameters together with tide gauge amplitudes measured in Japan we estimate apparent moment magnitudes of M w 8.0–8.2 and M w 8.5–8.6 for the 1906 central and 1922 north-central Chile earthquakes. The large discrepancy of the 1906 magnitude estimated from the tsunami observed in Japan as compared with those previously determined from seismic waves ( M s 8.4) suggests a deeper than average source with reduced tsunami excitation. A deep dislocation along the Chilean megathrust would favor uplift of the coast rather than beneath the sea, giving rise to a smaller tsunami and producing effects consistent with those observed in 1906. The 1922 magnitude inferred from far-field tsunami amplitudes appear to better explain the large extent of damage and the destructive tsunami that were locally observed following the earthquake than the lower seismic magnitudes ( M s 8.3) that were likely affected by the well-known saturation effects. Thus, a repeat of the large 1922 earthquake poses seismic and tsunami hazards in a region identified as a mature seismic gap.

Journal of Geophysical Research B: Solid Earth↗
USGS2020

Six-axis ground motion measurements of caldera collapse at Kīlauea Volcano, Hawaiʻi - More data, more puzzles?

Near‐field recordings of large earthquakes and volcano‐induced events using traditional seismological instrumentation often suffer from unaccounted effects of local tilt and saturation of signals. Recent hardware advances have led to the development of the blueSeis‐3A, a very broadband, highly sensitive rotational motion sensor. We installed this sensor in close proximity to permanently deployed classical instrumentation (i.e., translational seismometer, accelerometer, and tiltmeter) at the Hawaiian Volcano Observatory (USGS). There, we were able to record three ~Mw 5 earthquakes associated with large collapse events during the later phase of the 2018 Kīlauea summit eruption. Located less than 2 km from the origins of these sources, the combined six‐axis translational and rotational measurements revealed clear static rotations around all three coordinate axes. With these six component recordings, we have been able to reconstruct the complete time history of ground motion of a fixed point during an earthquake for the first time.

Hawaii↗
USGS2020

The U.S. Geological Survey’s Rapid Seismic Array Deployment for the 2019 Ridgecrest Earthquake Sequence

Rapid seismic deployments following large earthquakes capture ephemeral near‐field recordings of aftershocks and ambient noise that can provide valuable data for seismological studies. The U.S. Geological Survey installed 19 temporary seismic stations following the 4 July 2019 M w 6.4 and 6 July 2019 (UTC) M w 7.1 earthquakes near the city of Ridgecrest, California. The stations record the aftershock sequence beginning two days after the mainshock and are expected to remain in the field through approximately January 2020. The deployment augments the permanent seismic network in the area to improve azimuthal coverage and provide additional near‐field observations. This article summarizes the motivation and goals of the deployment; details of station installation, instrumentation, and configurations; and initial data quality and observations from the network. We expect these data to be useful for a range of studies including detailing near‐field variability in strong ground motions, determining stress drops and rupture directivity of small events, imaging the fault zone, documenting the evolution of crustal properties within and outside of the fault zone, and others.

California↗
USGS1991

The Loma Prieta earthquake, ground motion, and damage in Oakland, Treasure Island, and San Francisco

The basis of this study is the acceleration, velocity, and displacement wave-forms of the Loma Prieta earthquake (18 October 1989; M = 7.0) at two rock sites in San Francisco, a rock site on Yerba Buena Island, an artificial-fill site on Treasure Island, and three sites in Oakland underlain by thick sections of poorly consolidated Pleistocene sediments. The waveforms at the three rock sites display a strong coherence, as do the three sedimentary sites in Oakland. The duration of strong motion at the rock sites is very brief, suggestive of an unusually short source duration for an earthquake of this size, while the records in Oakland show strong amplification effects due to site geology. The S -wave group at Treasure Island is phase coherent with the Oakland records, but at somewhat diminished amplitudes, until the steps in acceleration at approximately 15 sec, apparently signaling the onset of liquefaction. All seven records clearly show shear-wave first motion opposite to that expected for the mainshock radiation pattern and peak amplitudes greater than expected for sites at these distances (95 ± 3 km) from an earthquake of this magnitude. While the association between these ground motion records and related damage patterns in nearby areas has been easily and eagerly accepted by seismological and engineering observers of them, we have had some difficulty in making such relationships quantitative or even just clear. The three Oakland records, from sites that form a nearly equilateral triangle about the Cypress Street viaduct collapse, are dominated by a long-period resonance (≃ 1 1/2-sec period) far removed from the natural frequency of the structure to transverse motion (2.5 Hz) or from high-frequency amplification bands observed in aftershock studies. A spectral ratio arbiter of this discrepancy confuses it further. The failure of the East Bay crossing of the San Francisco-Oakland Bay Bridge cannot be attributed to relative displacements of the abutments in Oakland and Yerba Buena Island, but the motions of the Bay Bridge causing failure remain unknown. The steps in acceleration at Treasure Island present unusual strong-motion accelerogram processing problems, and modeling suggests that the velocity and displacement waveforms are contaminated by a spurious response of the filtering operations to the acceleration steps. A variety of coincidences suggests that the Treasure island accelerogram is the most likely strong-motion surrogate for the filled areas of the Marina District, for which no mainshock records are available, but the relative contributions of bad ground, poor construction and truly strong ground motion to damage in the Marina District will never by known in any quantitative way. The principal lesson of all of this is that until a concerted effort is mounted to instrument ground and structures that are likely to fail during earthquakes, our understanding of the very complex relationships between strong ground motion and earthquake damage will, in general, remain rudimentary, imprecise, and vague.

California↗
USGS2025

Revisiting seismological discoveries of the inner core

Seismology has been used as a tool for understanding the current physical properties of the interior of the Earth and its dynamic evolution with remarkable success over the last century. Much of this progress is due to the ever‐expanding set of high‐quality quantitative observations of teleseismic waveforms recorded at seismographic stations worldwide. In this work, we revisit historical seismological studies that helped first identify a core distinct in physical properties from the overlying mantle, followed by the detection of an inner core that was eventually verified to be solid based on normal‐mode eigenperiods. Along with a brief overview of past studies of the Earth’s inner core, we examine the reproducibility of these results and discuss how historical data compare against modern observations. After accounting for past normal‐mode misidentifications, we confirm that introducing a solid inner core is required to afford significant improvements in fits to both radial modes and core‐sensitive spheroidal overtones. Strong shear dissipation in the inner core of the radial reference Earth model, REM1D ( ⁠⁠ Q u = 89.54 ), fits the reference datasets of both normal‐mode eigenperiods and quality factors accounting for physical dispersion. Because a liquid region would only have bulk dissipation, a narrow range of low Q u values that are preferred by the reference datasets affords additional evidence of a solid inner core. In addition, we find that there is little systematic bias in the timing accuracy of historical data, although large variances exist. Investigations into the temperature, composition, and evolution of the inner core, as well as the reproducibility of past studies, can benefit from the reconciliation of historical and modern seismological datasets.

Seismological Research Letters↗
USGS2017

Eastern Denali Fault surface trace map, eastern Alaska and Yukon, Canada

We map the 385-kilometer (km) long surface trace of the right-lateral, strike-slip Denali Fault between the Totschunda-Denali Fault intersection in Alaska, United States and the village of Haines Junction, Yukon, Canada. In Alaska, digital elevation models based on light detection and ranging and interferometric synthetic aperture radar data enabled our fault mapping at scales of 1:2,000 and 1:10,000, respectively. Lacking such resources in Yukon, we developed new structure-from-motion digital photogrammetry products from legacy aerial photos to map the fault surface trace at a scale of 1:10,000 east of the international border. The section of the fault that we map, referred to as the Eastern Denali Fault, did not rupture during the 2002 Denali Fault earthquake (moment magnitude 7.9). Seismologic, geodetic, and geomorphic evidence, along with a paleoseismic record of past ground-rupturing earthquakes, demonstrate Holocene and contemporary activity on the fault, however. This map of the Eastern Denali Fault surface trace complements other data sets by providing an openly accessible digital interpretation of the location, length, and continuity of the fault’s surface trace based on the accompanying digital topography dataset. Additionally, the digitized fault trace may provide geometric constraints useful for modeling earthquake scenarios and related seismic hazard.

Alaska, Yukon↗
USGS1913

Hawaiian Volcano Observatory bulletins

The Hawaiian Volcano Observatory (HVO) Bulletin series was an informal publication issued between the years 1913 to 1929. Individual issues contain information on volcanic and earthquake activity, volcano research, and volcano monitoring in Hawaii, and issues often included photographs, sketches, and data plots. Information on volcanic activity at other locations is also occasionally included. The Bulletin series was published by HVO through the Hawaiian Volcano Research Association. Weekly Bulletins (initially called Reports) were issued between June 28, 1913, and July 1, 1914. Bulletins were issued monthly after July 1, 1914, though they were still named Weekly Bulletins until January 1919. Starting with the February 1919 issue, the Bulletins were named Monthly Bulletins, and they continued to be issued monthly until the series ceased in July 1929. During a single year, 1915, Seismometric Bulletins were also issued quarterly. These four issues contain summaries of seismic observations recorded by the then-nascent Whitney Laboratory of Seismology, located underground in a vault near the summit of Kīlauea. Two of the bulletins are misnumbered: • April 1916 volume IV no. 4 incorrectly says April 1915 volume III no. 4 • September 1916 volume IV no. 9 incorrectly says September 1916 volume VI no. 9

Hawaii↗
USGS1913

Hawaiian Volcano Observatory bulletins - 1913

The Hawaiian Volcano Observatory (HVO) Bulletin series was an informal publication issued between the years 1913 to 1929. Individual issues contain information on volcanic and earthquake activity, volcano research, and volcano monitoring in Hawaii, and issues often included photographs, sketches, and data plots. Information on volcanic activity at other locations is also occasionally included. The Bulletin series was published by HVO through the Hawaiian Volcano Research Association. Weekly Bulletins (initially called Reports) were issued between June 28, 1913, and July 1, 1914. Bulletins were issued monthly after July 1, 1914, though they were still named Weekly Bulletins until January 1919. Starting with the February 1919 issue, the Bulletins were named Monthly Bulletins, and they continued to be issued monthly until the series ceased in July 1929. During a single year, 1915, Seismometric Bulletins were also issued quarterly. These four issues contain summaries of seismic observations recorded by the then-nascent Whitney Laboratory of Seismology, located underground in a vault near the summit of Kīlauea. Two of the bulletins are misnumbered: • April 1916 volume IV no. 4 incorrectly says April 1915 volume III no. 4 • September 1916 volume IV no. 9 incorrectly says September 1916 volume VI no. 9

Hawaii↗
USGS1914

Hawaiian Volcano Observatory bulletins - 1914

The Hawaiian Volcano Observatory (HVO) Bulletin series was an informal publication issued between the years 1913 to 1929. Individual issues contain information on volcanic and earthquake activity, volcano research, and volcano monitoring in Hawaii, and issues often included photographs, sketches, and data plots. Information on volcanic activity at other locations is also occasionally included. The Bulletin series was published by HVO through the Hawaiian Volcano Research Association. Weekly Bulletins (initially called Reports) were issued between June 28, 1913, and July 1, 1914. Bulletins were issued monthly after July 1, 1914, though they were still named Weekly Bulletins until January 1919. Starting with the February 1919 issue, the Bulletins were named Monthly Bulletins, and they continued to be issued monthly until the series ceased in July 1929. During a single year, 1915, Seismometric Bulletins were also issued quarterly. These four issues contain summaries of seismic observations recorded by the then-nascent Whitney Laboratory of Seismology, located underground in a vault near the summit of Kīlauea. Two of the bulletins are misnumbered: • April 1916 volume IV no. 4 incorrectly says April 1915 volume III no. 4 • September 1916 volume IV no. 9 incorrectly says September 1916 volume VI no. 9

Hawaii↗
USGS1915

Hawaiian Volcano Observatory bulletins - 1915

The Hawaiian Volcano Observatory (HVO) Bulletin series was an informal publication issued between the years 1913 to 1929. Individual issues contain information on volcanic and earthquake activity, volcano research, and volcano monitoring in Hawaii, and issues often included photographs, sketches, and data plots. Information on volcanic activity at other locations is also occasionally included. The Bulletin series was published by HVO through the Hawaiian Volcano Research Association. Weekly Bulletins (initially called Reports) were issued between June 28, 1913, and July 1, 1914. Bulletins were issued monthly after July 1, 1914, though they were still named Weekly Bulletins until January 1919. Starting with the February 1919 issue, the Bulletins were named Monthly Bulletins, and they continued to be issued monthly until the series ceased in July 1929. During a single year, 1915, Seismometric Bulletins were also issued quarterly. These four issues contain summaries of seismic observations recorded by the then-nascent Whitney Laboratory of Seismology, located underground in a vault near the summit of Kīlauea. Two of the bulletins are misnumbered: • April 1916 volume IV no. 4 incorrectly says April 1915 volume III no. 4 • September 1916 volume IV no. 9 incorrectly says September 1916 volume VI no. 9

Hawaii↗
USGS1916

Hawaiian Volcano Observatory bulletins - 1916

The Hawaiian Volcano Observatory (HVO) Bulletin series was an informal publication issued between the years 1913 to 1929. Individual issues contain information on volcanic and earthquake activity, volcano research, and volcano monitoring in Hawaii, and issues often included photographs, sketches, and data plots. Information on volcanic activity at other locations is also occasionally included. The Bulletin series was published by HVO through the Hawaiian Volcano Research Association. Weekly Bulletins (initially called Reports) were issued between June 28, 1913, and July 1, 1914. Bulletins were issued monthly after July 1, 1914, though they were still named Weekly Bulletins until January 1919. Starting with the February 1919 issue, the Bulletins were named Monthly Bulletins, and they continued to be issued monthly until the series ceased in July 1929. During a single year, 1915, Seismometric Bulletins were also issued quarterly. These four issues contain summaries of seismic observations recorded by the then-nascent Whitney Laboratory of Seismology, located underground in a vault near the summit of Kīlauea. Two of the bulletins are misnumbered: • April 1916 volume IV no. 4 incorrectly says April 1915 volume III no. 4 • September 1916 volume IV no. 9 incorrectly says September 1916 volume VI no. 9

Hawaii↗
USGS1917

Hawaiian Volcano Observatory bulletins - 1917

The Hawaiian Volcano Observatory (HVO) Bulletin series was an informal publication issued between the years 1913 to 1929. Individual issues contain information on volcanic and earthquake activity, volcano research, and volcano monitoring in Hawaii, and issues often included photographs, sketches, and data plots. Information on volcanic activity at other locations is also occasionally included. The Bulletin series was published by HVO through the Hawaiian Volcano Research Association. Weekly Bulletins (initially called Reports) were issued between June 28, 1913, and July 1, 1914. Bulletins were issued monthly after July 1, 1914, though they were still named Weekly Bulletins until January 1919. Starting with the February 1919 issue, the Bulletins were named Monthly Bulletins, and they continued to be issued monthly until the series ceased in July 1929. During a single year, 1915, Seismometric Bulletins were also issued quarterly. These four issues contain summaries of seismic observations recorded by the then-nascent Whitney Laboratory of Seismology, located underground in a vault near the summit of Kīlauea. Two of the bulletins are misnumbered: • April 1916 volume IV no. 4 incorrectly says April 1915 volume III no. 4 • September 1916 volume IV no. 9 incorrectly says September 1916 volume VI no. 9

Hawaii↗
USGS1918

Hawaiian Volcano Observatory bulletins - 1918

The Hawaiian Volcano Observatory (HVO) Bulletin series was an informal publication issued between the years 1913 to 1929. Individual issues contain information on volcanic and earthquake activity, volcano research, and volcano monitoring in Hawaii, and issues often included photographs, sketches, and data plots. Information on volcanic activity at other locations is also occasionally included. The Bulletin series was published by HVO through the Hawaiian Volcano Research Association. Weekly Bulletins (initially called Reports) were issued between June 28, 1913, and July 1, 1914. Bulletins were issued monthly after July 1, 1914, though they were still named Weekly Bulletins until January 1919. Starting with the February 1919 issue, the Bulletins were named Monthly Bulletins, and they continued to be issued monthly until the series ceased in July 1929. During a single year, 1915, Seismometric Bulletins were also issued quarterly. These four issues contain summaries of seismic observations recorded by the then-nascent Whitney Laboratory of Seismology, located underground in a vault near the summit of Kīlauea. Two of the bulletins are misnumbered: • April 1916 volume IV no. 4 incorrectly says April 1915 volume III no. 4 • September 1916 volume IV no. 9 incorrectly says September 1916 volume VI no. 9

Hawaii↗
USGS1919

Hawaiian Volcano Observatory bulletins - 1919

The Hawaiian Volcano Observatory (HVO) Bulletin series was an informal publication issued between the years 1913 to 1929. Individual issues contain information on volcanic and earthquake activity, volcano research, and volcano monitoring in Hawaii, and issues often included photographs, sketches, and data plots. Information on volcanic activity at other locations is also occasionally included. The Bulletin series was published by HVO through the Hawaiian Volcano Research Association. Weekly Bulletins (initially called Reports) were issued between June 28, 1913, and July 1, 1914. Bulletins were issued monthly after July 1, 1914, though they were still named Weekly Bulletins until January 1919. Starting with the February 1919 issue, the Bulletins were named Monthly Bulletins, and they continued to be issued monthly until the series ceased in July 1929. During a single year, 1915, Seismometric Bulletins were also issued quarterly. These four issues contain summaries of seismic observations recorded by the then-nascent Whitney Laboratory of Seismology, located underground in a vault near the summit of Kīlauea. Two of the bulletins are misnumbered: • April 1916 volume IV no. 4 incorrectly says April 1915 volume III no. 4 • September 1916 volume IV no. 9 incorrectly says September 1916 volume VI no. 9

Hawaii↗
USGS1920

Hawaiian Volcano Observatory bulletins - 1920

The Hawaiian Volcano Observatory (HVO) Bulletin series was an informal publication issued between the years 1913 to 1929. Individual issues contain information on volcanic and earthquake activity, volcano research, and volcano monitoring in Hawaii, and issues often included photographs, sketches, and data plots. Information on volcanic activity at other locations is also occasionally included. The Bulletin series was published by HVO through the Hawaiian Volcano Research Association. Weekly Bulletins (initially called Reports) were issued between June 28, 1913, and July 1, 1914. Bulletins were issued monthly after July 1, 1914, though they were still named Weekly Bulletins until January 1919. Starting with the February 1919 issue, the Bulletins were named Monthly Bulletins, and they continued to be issued monthly until the series ceased in July 1929. During a single year, 1915, Seismometric Bulletins were also issued quarterly. These four issues contain summaries of seismic observations recorded by the then-nascent Whitney Laboratory of Seismology, located underground in a vault near the summit of Kīlauea. Two of the bulletins are misnumbered: • April 1916 volume IV no. 4 incorrectly says April 1915 volume III no. 4 • September 1916 volume IV no. 9 incorrectly says September 1916 volume VI no. 9

Hawaii↗
USGS1921

Hawaiian Volcano Observatory bulletins - 1921

The Hawaiian Volcano Observatory (HVO) Bulletin series was an informal publication issued between the years 1913 to 1929. Individual issues contain information on volcanic and earthquake activity, volcano research, and volcano monitoring in Hawaii, and issues often included photographs, sketches, and data plots. Information on volcanic activity at other locations is also occasionally included. The Bulletin series was published by HVO through the Hawaiian Volcano Research Association. Weekly Bulletins (initially called Reports) were issued between June 28, 1913, and July 1, 1914. Bulletins were issued monthly after July 1, 1914, though they were still named Weekly Bulletins until January 1919. Starting with the February 1919 issue, the Bulletins were named Monthly Bulletins, and they continued to be issued monthly until the series ceased in July 1929. During a single year, 1915, Seismometric Bulletins were also issued quarterly. These four issues contain summaries of seismic observations recorded by the then-nascent Whitney Laboratory of Seismology, located underground in a vault near the summit of Kīlauea. Two of the bulletins are misnumbered: • April 1916 volume IV no. 4 incorrectly says April 1915 volume III no. 4 • September 1916 volume IV no. 9 incorrectly says September 1916 volume VI no. 9

Hawaii↗