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Degree: Master of Science Department: Science / This study examined conceptions about earthquakes held by the selected high school students in Lesotho. A survey was carried out at one high school with students from three different grades; Form A students who had not yet received formal instruction about earthquakes, and Form C and Form D students who had dealt with the topic in school. Some of the students in the sample had experienced an earthquake. A diagnostic test was used to elicit conceptions from 130 students. Follow-up interviews were conducted with 6 students, with the purpose of probing certain responses from the test. In particular, test responses that were probed included; first, those which showed confusion between earthquakes and volcanoes, and second, those which used indigenous beliefs to explain causes of earthquakes. The conceptions held by students in the three grades were analysed and compared. From the results the following findings emerged: First, many students appear to be confused in their understanding between earthquakes and volcanoes, particularly those who had received classroom instruction on these concepts. Some of the students could not distinguish between an earthquake and a volcano, while others seem to think that earthquake occurrences are always linked to volcanic activity. Second, several students across the three grades could not differentiate between movements of the earth’s crust which result in earthquakes and the larger scale movements, i.e. the rotation and revolution of the earth. Third, generally students across the three grades appear to have scientifically correct ideas about the causes of earthquakes. Also, the majority of students attributed the causes of earthquakes to water, perhaps because the earthquake in their area was caused by impoundment of the dam. However, students seemed to be uninformed about the mechanisms or processes behind the occurrence of earthquakes. Finally, a few students across the grades used indigenous beliefs to explain earthquakes. With an awareness of the conceptual and cultural difficulties students in Lesotho are likely to encounter in the learning of earthquakes, teachers can prepare in advance to handle such issues, as they are critical in the understanding of the phenomenon of earthquakes.

Thesis advisor: John E. Ebel / In 1638, an earthquake with an estimated MLg of 6.5 ± 0.5 struck New England and adjacent southeastern Canada producing severe shaking in Boston, Massachusetts and Trois-Rivieres, Quebec. Previously published analyses of felt reports place the possible epicenter somewhere within a broad region including NY, NH, VT and ME. The possible source region had been further refined by the application of Omori's Law rate of aftershock decay combined with estimated rupture extent based on modern seismicity, which together suggest that a seismic event of MLg 6.5 ± 0.5 could have occurred in central New Hampshire in 1638. In order to more clearly define the possible active fault for this earthquake and determine its seismotectonic framework within central New Hampshire, three geophysical methods were used to analyze recent, digitally recorded seismic data. The three methods are a relative location analysis, computation of focal mechanisms and computation of focal depths based on fundamental mode Rayleigh waves. The combined results of the analyses are consistent with a thrust fault trending NNW - SSE and possibly dipping eastward in this postulated 1638 epicentral zone. Modern earthquakes in the postulated source area of the 1638 earthquake occur at focal depths of ~3 to 10 km with many of the events occurring below 5 km, suggesting, that this is the depth range of the 1638 rupture. Depending on the depth of the pre-Silurian basement of the Central Maine Terrane, the source of the MLg 6.5 ± 0.5 earthquake of 1638 may be a basement-involved thrust fault or a reactivated east-dipping thrust fault located between the nappes of the overlying Silurian-Devonian aged metasedimentary rocks. When the postulated fault plane is projected to the surface, portions of the Pemigewasset and Merrimack Rivers are found to flow within its surface expression, which suggests that the courses of these rivers may be fault controlled. A fourth research technique, a field survey, was undertaken to search for earthquake-induced liquefaction features along the Pemigewasset, Merrimack and Winnipesaukee Rivers as well as of the Suncook River Avulsion site. Several small strata-bound soft-sediment deformation structures were found during the survey. Although some of the features may be seismically induced, they may also have formed as the result of depositional processes and therefore cannot be attributed to the 1638 earthquake. / Thesis (MS) — Boston College, 2013. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Earth and Environmental Sciences.