Investigation of the Relationship of Earthquakes and Underground Waste Disposal in The El Dorado Area, Arkansas

From December, 1983 to September, 1989 twelve small earthquakes were recorded for the El Dorado, Arkansas area. Magnitudes of these earthquakes were well below damaging levels. Prior to this time no seismicity was reported in the area, suggesting that the earthquakes were not naturally occurring and may have been the result of human activity. El Dorado is located at the margin of a region of underground waste brine disposal and along a major fault zone. Elevated pore pressures resulting from brine disposal may have reduced the normal (locking) stresses across fault surfaces and triggered fault movement. Two injection wells (Great Lakes Chemical Corporation SWD# 7 and 13) in the El Dorado South field are in closest proximity to fault surfaces at the depth of injection. The two wells also lie at the center of the macroseismic area and show increases in injection rates prior to periods of seismicity. These relationships suggest that pressured fluid injection triggers earthquakes in the area. Future research to corroborate these results should include detailed seismological studies of the El Dorado South field and detailed studies of formation pressures, in situ stresses and geologic structure for all sites of pressured fluid injection and secondary oil recovery operations in the region

Seismic vulnerability assessment of the old city centre of Seixal, Portugal

The seismic vulnerability assessment of old traditional masonry building stocks, in a seismic risk mitigation perspective, is truly essential not only for buildings with recognized historical and patrimonial value, but also, in relation to regular buildings. In this sense, this paper approaches the issue of the seismic vulnerability assessment of masonry buildings through the application of a simplified methodology to building stock of the old city centre of Seixal, Portugal. This methodology is based on a vulnerability index, suitable in the evaluation of damage and in the creation of large scale loss scenarios (economical and human). Over 500 buildings were evaluated in accordance with the referred methodology and the results obtained were then integrated into a Geographical Information System tool. The integration of this kind of vulnerability and loss results into a GIS tool allows that city councils or regional authorities make their decisions based on a global view of the site under analysis, which led to more accurate and faster decisions either in terms of risk mitigation strategies or rehabilitation plans. This tool can also assumes great importance in the construction of safety and rescue plans

Seismic risk in the city of Al Hoceima (north of Morocco) using the vulnerability index method, applied in Risk-UE project

The final publication is available at Springer via http://dx.doi.org/10.1007/s11069-016-2566-8Al Hoceima is one of the most seismic active regions in north of Morocco. It is demonstrated by the large seismic episodes reported in seismic catalogs and research studies. However, seismic risk is relatively high due to vulnerable buildings that are either old or don’t respect seismic standards. Our aim is to present a study about seismic risk and seismic scenarios for the city of Al Hoceima. The seismic vulnerability of the existing residential buildings was evaluated using the vulnerability index method (Risk-UE). It was chosen to be adapted and applied to the Moroccan constructions for its practicality and simple methodology. A visual inspection of 1102 buildings was carried out to assess the vulnerability factors. As for seismic hazard, it was evaluated in terms of macroseismic intensity for two scenarios (a deterministic and probabilistic scenario). The maps of seismic risk are represented by direct damage on buildings, damage to population and economic cost. According to the results, the main vulnerability index of the city is equal to 0.49 and the seismic risk is estimated as Slight (main damage grade equal to 0.9 for the deterministic scenario and 0.7 for the probabilistic scenario). However, Moderate to heavy damage is expected in areas located in the newer extensions, in both the east and west of the city. Important economic losses and damage to the population are expected in these areas as well. The maps elaborated can be a potential guide to the decision making in the field of seismic risk prevention and mitigation strategies in Al Hoceima.Peer ReviewedPostprint (author's final draft

Analysis of the 2016 Amatrice earthquake macroseismic data

On August 24, 2016, a sudden MW 6.0 seismic event hit central Italy, causing 298 victims and significant damage to residential buildings and cultural heritage. In the days following the mainshock, a macroseismic survey was conducted by teams of the University of Padova, according to the European Macroseismic Scale (EMS98). In this contribution, a critical analysis of the collected macroseismic data is presented and some comparisons were performed with the recent 2012 Emilia sequence

Instrumental intensity as a tool for post-earthquake damage assessment: validation for the strong Vrancea earthquakes of August 1986 and May 1990

The frequency-dependent spectrum based seismic intensity, also called instrumental intensity, is calculated basically from the integration of the square values of spectral acceleration ordinates. The values of the instrumental intensity are calibrated to match the values of the EMS-98 intensity scale, providing a promising analytical indicator for estimating the destructive potential of earthquakes. Previous studies have shown that the proposed index could be used as a basis for the development of a new improved seismic intensity scale. The paper presents a set of maps describing the spatial distribution of instrumental intensity ordinates for three seismic events recorded in 1986 and 1990. These events, generated by the Vrancea source, are the strongest earthquakes in Romania for which accelerographic data was recorded at multiple stations. Intensity maps were generated for separate significant frequency bands, in order to reveal the destructiveness of the considered earthquakes for different building categories. Results were compared and correlated with previous studies on Vrancea earthquakes and with information provided by building damage reports from the considered earthquakes.spectrum based seismic intensity; Vrancea earthquakes; EMS-98 seismic intensity scale; seismic intensity maps

The macroseismic survey of the 27 February 2008 Market Rasen earthquake

Immediately following the occurrence of the Market Rasen earthquake on 27 February 2008 (5.2 ML, 4.5 Mw), an online questionnaire was opened on the BGS web site to collect felt reports. In addition, questionnaire data were collected automatically by USGS as part of the “Did You Feel It?” (DYFI) programme (Wald et al. 1999), and also by EMSC as part of its European monitoring. Some additional data were also gathered by agencies on the fringe of the felt area, notably ROB in Brussels, and DIAS in Dublin. This report summarises the findings

The vulnerability assessment of current buildings by a macroseismic approach derived from the EMS-98 scale

A hierarchical family of Damage Probability Matrices (DPM) has been derived in this paper from the ones implicitly contained in the EMS-98 Macroseismic Scale for 6 vulnerability classes. To this aim the linguistic definitions provided by the scale, and the associated fuzzy sub-sets of the percentage of buildings, have been completed according to reliable hypotheses. A parametric representation of the corresponding cumulative probability distributions is moreover provided, through a unique parameter: a vulnerability index variable in the range from 0 to 1 and independent of the macroseismic intensity. Finally, an innovative macroseismic approach allowing the vulnerability analysis of building typologies is defined within the European Macroseismic Scale (EMS-98) and qualitatively related to the vulnerability classes. Bayes’ theorem allows the upgrading of the frequencies when further data about the built-environment or specific properties of the buildings are available, allowing the identification of a different behaviours with respect to the one generally considered for the typology. Fuzzy measures of any damage function can be derived, using parametric or nonparametric damage probability matrices. For every result of the seismic analysis, the procedure allows supply to the user of the final uncertainty connected with the aforementioned fuzzy relation between the probability of the damage grade, the macroseismic intensity and the vulnerability classes