Network Bulletin Research Articles

Telephone networks, BBSes, and the emergence of the transnational ‘warez scene’

ABSTRACTThis article analyzes how software pirates who formed the ‘warez scene’ appropriated telephone network infrastructures and Bulletin Board System (or BBS) technology to circulate computer software across national borders. This paper is shedding more light on the roots of contemporary internet-based software piracy by investigating how appropriation of international telephone networks contributed to the globalization of digital software distribution. It also highlights the mundane aspects of the organization of media convergence on the junction between analog and digital technologies. Here I argue that the use of telephone networks as a means of transnational software distribution is an instance of actors setting up a convergent media environment driven by the cultural logic of a specific subculture. My paper provides an overview of BBS technology to demonstrate how it linked analog and digital domains and then outlines its cultural significance, ultimately discussing the appropriation of BBSes and their role in transnational expansion of ‘the scene’.

Spatiotemporal characterization of interswarm period seismicity in the focal area Nový Kostel (West Bohemia/Vogtland) by a short-term microseismic study

The West Bohemia/Vogtland region is one of the seismically most interesting areas in Europe because of its swarm-like occurrence of seismicity. The installation of the local West Bohemian seismological network (WEBNET) has made the recording of small magnitude seismicity (detection threshold ML≈−0.5) possible. We investigated if microseismicity exists below the detection threshold of WEBNET. A microseismic field campaign was carried out in the focal area Nový Kostel. The measurement was performed with three small arrays lasting for 6 d in a seismically quiet, interswarm period. We were able to detect and locate 13 microearthquakes in the magnitude range −1.5 ≤ ML ≤−0.1 and achieved a detection threshold about one magnitude lower than the local network. A relative location suggests that the recorded seismicity is rather related to a specific fault segment than randomly distributed. The determined fault zone is aligned NW—SW and confirms the viability of mapping active faults with short-term measurements. The results demonstrate that a linear extrapolation of the b-value, determined by the network bulletin, down to ML = −0.5 fits well with the amount of our recorded events.

Fogo Volcano, Cape Verde Islands: seismicity-derived constraints on the mechanism of the 1995 eruption

Seismic data recorded in the vicinity of the active vent of the 1995 Fogo eruption [Global Volcanism Network Bulletin, 1995, 20(3) 2–4.] is used to constrain the associated stress field and deformation. Using the frequency content of the seismograms to distinguish between brittle fracture of cold host rock and deformation in the vicinity of the intruding magma, a sub-vertical dyke with 060° strike is identified as the feeder of the eruption, and delineated down to a depth of about 4 km. The local stress field during the eruption is estimated from composite focal mechanisms. Besides the expected σ3 direction normal to the dyke, a group of focal solutions point to a stress field with nearly dyke-parallel σ3, which is interpreted as a re-adjustment of the edifice following the eruption, maybe partially controlled by gravity. This effect may have increased the instability of the steep eastern flank of the island, since the deformation detected during the magma drainback is compatible with predominantly dip-slip motion on east-dipping surfaces.

The 1994 Southern California Network Bulletin

The Pasadena Office of the U.S. Geological Survey and the California Institute of Technology Seismology Laboratory (Caltech Seismo Lab) operate a network of more than 300 remote seismometers in southern California called the S outhern C alifornia S eismic N etwork (SCSN). Signals from these sites are telemetered to the central processing site at the Caltech Seismo Lab in Pasadena. These signals are continuously monitored by computers that detect and record thousands of earthquakes each year. Phase arrival times for these events are picked by analysts and archived along with digital seismograms. Data acquisition, processing and archiving is achieved using the CUSP system (Dollar, 1989). These data are used to compile the SCSN Catalog of Earthquakes, a list beginning in 1932 that currently contains more than 258,000 events. This article contains selected parts from the USGS OpenFile Report entitled “Southern California Network Bulletin: January–December 1994” (Wald et al. , 1995). SEISMICITY SUMMARY & STATUS OF...

The Southern California Network Bulletin: 1990-1993 Summary

INTRODUCTION The Southern California Network Bulletin began publication semi-annually as a U.S. Geological Survey Open-File Report in 1985. In 1988 it became an annual publication. The Network Bulletin is completed at the beginning of each year and contains information about Southern California Seismic Network (SCSN) activities during the previous year. Information in each bulletin includes: new stations, discontinued stations, status of earthquake data processing, CUSP (California-USGS Seismic Processing) activities, a summary of seismicity, short research articles about recent significant earthquakes in southern California or other topics related to the SCSN, and information about accessing and using the SCSN and TERRAscope data. TERRAscope is the network of high dynamic range, broadband instruments in southern California. This article contains selected parts from the Network Bulletins from 1990-1993 (Wald et al. , 1991; Wald et al. , 1992; Wald et al. , 1993; Wald et al. , 1994). The Pasadena Office of the U.S. Geological Survey together...

An exercise in automating seismic record analysis and network bulletin production

A long-standing problem in observational seismology is that of automating network operation. In this study we report an experiment that uses the detector described in Ruud and Husebye (1992) for automatically picking P and S arrivals in local event records from the Norwegian Seismic Network (NSN). The analysis was performed on prescreened waveform segments known to contain local events. For automatic epicenter determination a novel, robust grid-search method well-suited for estimation problems with nonGaussian observational errors is introduced in order to handle outliers. In our experiment, 49 local events from the August 1991 NSN bulletin were located. The number of detecting stations varied from 3 to 10, with an average of 5 of a total of 15 stations. P - and S -picking errors were small, mostly within 0.5 sec for both P and S . Mis-identification of the P - and S -phase was more frequent; this affected about 15% of the picks. Even for events with several large arrival time outliers (up to 40 to 50% of total) satisfactory epicenter determinations were obtained. The median location difference of our “automatic” solutions compared with those in the NSN bulletin based on analyst picked and identified phases was 15 km. For 90% of the events the difference was less than 50 km.

Transport of Cerro Hudson SO2 clouds

The Cerro Hudson volcano in southern Chile (45.92°S, 73.0°W) emitted large ash and sulfur dioxide clouds on August 12–15, following several days of minor activity [Global Volcanism Network Bulletin, 1991]. The SO2 clouds were observed using (preliminary) near real‐time data from the Total Ozone Mapping Spectrometer (TOMS) as they encircled the south polar region. The injection of SO2 into the stratosphere has essentially created a gigantic chemical tracer that could provide new insights into the wind patterns and seasonal circulation around the Antarctic region.around the Antarctic region. The TOMS instrument, on board the National Aeronautic and Space Administration's Nimbus 7 satellite, measures the ratio of backscattered Earth radiance to incoming solar irradiance in the ultraviolet spectrum. Although originally designed to measure ozone, it was later discovered that the TOMS instrument could also detect and quantify SO2 [Krueger, 1985]. After this discovery, measurements from TOMS were examined for SO2 emissions for all recorded volcanic eruptions since Nimbus‐7 was launched in October 1978, and current data are analyzed as new eruptions occur. The satellite is in a polar, Sun‐synchronous orbit so that it crosses the equator at local noon and observes the whole sunlit Earth in approximately 14 orbits each day. Total column amounts of SO2 are determined that represent the amount of gas affecting the reflection of ultraviolet light through a column of the atmosphere from the satellite to the reflecting surface, Earth, given in terms of milli atmospheres centimeter (1000 milli atm cm = a gas layer 1‐cm thick at STP). The mass of SO2 is calculated by integrating over the cloud area to obtain a volume, then converting to tons.

Initial results from the Intelligent Monitoring System

AbstractThe Intelligent Monitoring System (IMS) integrates advanced technologies in a knowledge-based distributed system that automates most of the seismic data interpretation process. Results from IMS during its first 8 weeks of operation (1 October through 25 November 1989) are analyzed to evaluate its performance. During this test period, the IMS processed essentially all data recorded by the NORESS and ARCESS high-frequency arrays in Norway. The emphasis was on detection and location of regional events within 2,000 km of these arrays. All events were reviewed and corrected if necessary by a skilled analyst. The final IMS Bulletin for the period includes 1,580 regional events (∼280 events/day). Approximately 55 per cent were smaller than MLg 1, with the largest just over MLg 3.Comparison of IMS locations in southern Finland and northwestern USSR (800 to 900 km from both arrays) with event locations from the University of Helsinki's local network bulletin are used to assess the detection and location capabilities of the system. Two or more phases (minimum needed to locate) were detected for 96 per cent of the events with magnitude greater than 2.5. The median separation between the IMS and Helsinki locations for all common events was 23.5 km. A consistent bias in arrival-time and azimuth residuals was observed for events in small geographic areas, indicating that refined travel-time models and path corrections could further improve location accuracy.The knowledge base in this first version of IMS was based on analysis of NORESS data, and many of the errors in interpretation corrected by the analysts can be attributed to differences encountered when this knowledge is used to interpret ARCESS data. Nevertheless, nearly 60 per cent of the events appearing in the final bulletin are automatic solutions approved without change or moved (by analyst corrections) less than 25 km from the automatic locations. The IMS had the most difficulty interpreting the overlapping signals generated by closely spaced explosions commonly detonated at mines in the Kola Peninsula and northern Sweden. Using the knowledge acquisition facilities included in the system, the deficiencies responsible for these and other errors are isolated, leading to development of new knowledge to be incorporated in the next version of the IMS knowledge base.