Seismotectonic analyses of Karachi Arc, Southern Kirthar Fold Belt, Pakistan

In this study geomorphological and seismotectonic analyses were carried out in Karachi arc area, southernPakistan to locate relatively safe areas from earthquakes disasters. Karachi arc is the southern extremity of the Kirtharmountain chain that occupies a major part of southern Pakistan and is comprised of a number of narrow, elongatedmountain ranges, i.e. Laki, Kirthar, Khud, Pab and Mor ranges. Based on geomorphological and seismotectonicanalyses Karachi arc area has been divided into three parts. These parts are northern, frontal and southern part. Thenorthern part of Karachi arc is seismically active where minor to moderate (3-5.9Mb) earthquakes occurred. Somebasement structures in Sehwan area seem to be still active and affected by the present-day transpressional stress field.The frontal part of Karachi arc is also active as manifested by the existence of active faults in Jhimpir, Surjan andMeting areas. These embryonic structures in the eastern part of the Arc are indicators of active deformation of Karachiarc. Presently the active deformation is taking place in frontal and northern parts of the arc, while the southern part thathas experienced deformation prior to Quaternary time is inactive and is relatively stable geoblock. The instrumental andhistoric seismicity record of the adjoining areas of Karachi arc show that the area has experienced light to moderateseismic events (4-5.9) with occasional occurrence of strong and major earthquakes. Any major or strong event in Katchrift zone, Makran subduction zone and Ornach-Nal fault zone may cause intensity of VII to VIII in Karachi arc area aswell as Karachi city of environmental seismic intensity scale 2007.

Seismotectonic analyses of Karachi Arc, Southern Kirthar Fold Belt, Pakistan

In this study geomorphological and seismotectonic analyses were carried out in Karachi arc area, southernPakistan to locate relatively safe areas from earthquakes disasters. Karachi arc is the southern extremity of the Kirtharmountain chain that occupies a major part of southern Pakistan and is comprised of a number of narrow, elongatedmountain ranges, i.e. Laki, Kirthar, Khud, Pab and Mor ranges. Based on geomorphological and seismotectonicanalyses Karachi arc area has been divided into three parts. These parts are northern, frontal and southern part. Thenorthern part of Karachi arc is seismically active where minor to moderate (3-5.9Mb) earthquakes occurred. Somebasement structures in Sehwan area seem to be still active and affected by the present-day transpressional stress field.The frontal part of Karachi arc is also active as manifested by the existence of active faults in Jhimpir, Surjan andMeting areas. These embryonic structures in the eastern part of the Arc are indicators of active deformation of Karachiarc. Presently the active deformation is taking place in frontal and northern parts of the arc, while the southern part thathas experienced deformation prior to Quaternary time is inactive and is relatively stable geoblock. The instrumental andhistoric seismicity record of the adjoining areas of Karachi arc show that the area has experienced light to moderateseismic events (4-5.9) with occasional occurrence of strong and major earthquakes. Any major or strong event in Katchrift zone, Makran subduction zone and Ornach-Nal fault zone may cause intensity of VII to VIII in Karachi arc area aswell as Karachi city of environmental seismic intensity scale 2007.

History of the Environmental Seismic Intensity Scale ESI-07

This brief note aims to describe the history, from its early original idea, of the new macroseismic scale: The Environmental Seismic Intensity Scale 2007 (ESI 2007). It can be used together with other existing scales or alone when needed for measuring the intensity of an earthquake on the basis of the primary and secondary effects of a seismic event on the natural environment. These effects could be the major sources of earthquake hazards, as recently proved. This note also aims to contribute to the understanding of processes that induced the researcher to develop an idea, to pursue it, and bring it to its end, first through the help of valuable Italian researchers and then through the constructive exchange of ideas with researchers of different cultural backgrounds operating almost everywhere in the world. This note is sponsored and approved by the International Union for Quaternary Research (INQUA), and the Environmental Seismic Intensity scale (ESI-07) was published in 2007 after a revision process of about eight years.

A Study on the 2016 Kumamoto Earthquake: Citizen’s Evaluation of Earthquake Information and Their Evacuation and Sheltering Behaviors

In order to reveal the current status and issues of the victims of the 2016 Kumamoto Earthquake eight months after its occurrence, we conducted large-scale random sample questionnaire surveys with victims aged 18 and over in the most affected municipalities from November to December 2016. We decided to sample a total of 7,000 victims (1,600 from Kumamoto City and 5,400 from the other thirteen municipalities) with an expected collection rate of 25% and a sampling error of 5%; 3,272 victims effectively responded to the questionnaires (effective collection rate: 46.7%). The Kumamoto Earthquake was a series of earthquakes including foreshocks and main shocks of magnitude 7 on the Japanese seismic intensity scale, and aftershocks that appear to have significantly influenced the victims’ response behaviors as well as the recovery and reconstruction of the affected areas.The questionnaire survey on whether the victims’ pre-earthquake knowledge and awareness had any influence on their post-earthquake behaviors reveals that not more than 30% were aware of the active faults present in their areas before the earthquake occurred and that half of them hoped that no earthquakes would occur. On the other hand, the victims who were aware of the active faults present in their areas and who were afraid that an earthquake could occur within 10 years had planned accordingly and had stocked the necessary goods and provisions.The questionnaire survey on how the victims behaved in the event of the foreshocks and main shocks reveals that about half of them evacuated and found shelter after the foreshocks. Those who feared any aftershocks, and the damage to their buildings due to the aftershocks, evacuated and took shelter. Those whose buildings were not damaged and whose lifelines were available did not evacuate or take shelter. After the main shock, about 70% of the victims evacuated and took shelter because, in addition to their fears of the aftershocks, their buildings were actually damaged and their lifelines had been rendered unavailable.The questionnaire survey on whether the victims’ pre-earthquake knowledge and awareness had any influence on their post-earthquake behaviors reveals that in the event of an earthquake, like in the case of the foreshocks of the Kumamoto Earthquake in which human beings and buildings were not so scathed and people could not decide whether to evacuate or take shelter, those with more pre-earthquake knowledge and with awareness of earthquake damage better anticipated the aftershock occurrences. On the other hand, in the event of the main shocks of the Kumamoto Earthquake, in which there was great damage to humans and buildings, people with or without pre-earthquake knowledge and awareness on earthquake damage were urged to evacuate and take shelter.The questionnaire survey on whether aftershock information was properly communicated to the victims reveals that they followed the information on aftershocks broadcast by TVs and radios immediately after the foreshock had occurred. The victims did not follow the Meteorological Agency’s press release on the aftershocks on the afternoon of the following day in order to get an update. Instead, they took the information broadcast by TVs and radios as “no great aftershocks would occur in the future,” which was completely different from what the Meteorological Agency’s press release intended. The questionnaire survey on the influences of the aftershock information on the victims’ evacuation and sheltering behaviors reveals that the Meteorological Agency’s press release on the following day of the foreshock occurrence stated that the probability of the aftershock occurrence of lower 6 or over on the Japanese seismic intensity scale is 20% in the following three days, and that of the aftershock occurrence of upper 5 or over on the Japanese seismic intensity scale is 40%. This seems to have had a greater influence on the behaviors of the victims who assumed that “no great aftershocks would occur in the future” as compared to the behaviors of those who assumed that “an aftershock could occur anytime in the future” and “a big aftershock might occur in the future.”With regard to the movements in the victims’ long-term post-earthquake residences and evacuation destinations, 57.5% of the total victims stayed at home after the foreshock occurrence, which is not so different from the case of the Hanshin-Awaji (Kobe) Earthquake, an inland earthquake with relatively few aftershock activities. However, the ratio of the victims who stayed at home stood at 28.7% after the main shock occurrence, at 32.8% on the first weekend or about four days after the foreshock occurrence, and at 49% in the week following the earthquake occurrence, which indicates that more victims evacuated and sought shelter outdoors in cars, tents, and vacant grounds as seen in the case of the Mid-Niigata Earthquake, which witnessed many aftershock activities. Therefore, the evacuation behavior pattern in the Kumamoto Earthquake may be regarded as a cross between the Hanshin-Awaji (Kobe) Earthquake and the Mid-Niigata Earthquake.

Re-evaluation of the macroseismic effects produced by the March 4, 1977, strong Vrancea earthquake in Romanian territory

<p>In this paper, the macroseismic effects of the subcrustal earthquake in Vrancea (Romania) that occurred on March 4, 1977, have been re-evaluated. This was the second strongest seismic event that occurred in this area during the twentieth century, following the event that happened on November 10, 1940. It is thus of importance for our understanding of the seismicity of the Vrancea zone. The earthquake was felt over a large area, which included the territories of the neighboring states, and it produced major damage. Due to its effects, macroseismic studies were developed by Romanian researchers soon after its occurrence, with foreign scientists also involved, such as Medvedev, the founder of the Medvedev-Sponheuer-Karnik (MSK) seismic intensity scale. The original macroseismic questionnaires were re-examined, to take into account the recommendations for intensity assessments according to the MSK-64 macroseismic scale used in Romania. After the re-evaluation of the macroseismic field of this earthquake, the intensity dataset was obtained for 1,620 sites in Romanian territory. The re-evaluation was necessary as it has confirmed that the previous macroseismic map was underestimated. On this new map, only the intensity data points are plotted, without tracing the isoseismals.</p>

Study on Instrumental Intensity Using Wenchuan Earthquake Records

This paper invesigates the peak ground acceleration (PGA) and peak ground velocity (PGV) regression equations as well as the PGA or PGV middle values in Chinese seismic intensity scale 2008 (the CSIS 2008), using the Wenchuan earthquake records of China with the full seismic information. Based on the analytical results, the PGA-V method is proposed to assess the instrumental intensity which combines both PGA and PGV. Besides, a problem is raised to further verify and modify the middle values of PGA or PGV for the seismic intensity VI and VII in the CSIS 2008.

Application of Environmental Seismic Intensity scale (ESI 2007) to Krn Mountains 1998 <i>M</i>_w = 5.6 earthquake (NW Slovenia) with emphasis on rockfalls

The 12 April 1998 Mw = 5.6 Krn Mountains earthquake with a maximum intensity of VII–VIII on the EMS-98 scale caused extensive environmental effects in the Julian Alps. The application of intensity scales based mainly on damage to buildings was limited in the epicentral area, because it is a high mountain area and thus very sparsely populated. On the other hand, the effects on the natural environment were prominent and widespread. These facts and the introduction of a new Environmental Seismic Intensity scale (ESI 2007) motivated a research aimed to evaluate the applicability of ESI 2007 to this event. All environmental effects were described, classified and evaluated by a field survey, analysis of aerial images and analysis of macroseismic questionnaires. These effects include rockfalls, landslides, secondary ground cracks and hydrogeological effects. It was realized that only rockfalls (78 were registered) are widespread enough to be used for intensity assessment, together with the total size of affected area, which is around 180 km2. Rockfalls were classified into five categories according to their volume. The volumes of the two largest rockfalls were quantitatively assessed by comparison of Digital Elevation Models to be 15 × 106 m3 and 3 × 106 m3. Distribution of very large, large and medium size rockfalls has clearly defined an elliptical zone, elongated parallel to the strike of the seismogenic fault, for which the intensity VII–VIII was assessed. This isoseismal line was compared to the tentative EMS-98 isoseism derived from damage-related macroseismic data. The VII–VIII EMS-98 isoseism was defined by four points alone, but a similar elongated shape was obtained. This isoseism is larger than the corresponding ESI 2007 isoseism, but its size is strongly controlled by a single intensity point lying quite far from others, at the location where local amplification is likely. The ESI 2007 scale has proved to be an effective tool for intensity assessment in sparsely populated mountain regions not only for very strong, but for moderate earthquakes as well. This study has shown that the quantitative definition of rockfall size and frequency, which is diagnostic for each intensity, is not very precise in ESI 2007, but this is understandable since the rockfall size is related not only to the level of shaking, but also depends highly on the vulnerability of rocky slopes.