453/01 GEOLOGY - GL3 GEOLOGY AND THE HUMAN ENVIRONMENT. P.M. TUESDAY, 11 January (1 hour 15 minutes)

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1 Candidate Name Centre Number Candidate Number WELSH JOINT EDUCATION COMMITTEE General Certificate of Education Advanced Subsidiary/Advanced CYD-BWYLLGOR ADDYSG CYMRU Tystysgrif Addysg Gyffredinol Uwch Gyfrannol/Uwch 453/01 GEOLOGY - GL3 GEOLOGY AND THE HUMAN ENVIRONMENT P.M. TUESDAY, 11 January 2005 (1 hour 15 minutes) For Examiner s Use. Section A 1 2 Section B Total 50 INSTRUCTIONS TO CANDIDATES TJ* Write your name, centre number and candidate number in the spaces at the top of this page. Answer all questions from Section A and one question from Section B. All questions must be answered in this booklet. INFORMATION FOR CANDIDATES The number of marks is given in brackets at the end of each question or part-question. Candidates are reminded that marking will take into account the use of examples and the quality of communication used in answers, especially in the structured essay. No certificate will be awarded to a candidate detected in any unfair practice during the examination.

2 2 SECTION A Examiner Answer both questions, 1 and 2, on the lines provided in the question. 1. Table 1 is an account of the events leading up to the major eruption of Mount St. Helens in Figure 1 shows profiles of Mount St. Helens together with earthquake data associated with the May 18 th eruption. Volcanic activity at Mount St. Helens began on 27th March, 1980 with explosive ash and steam eruptions. At 8:32 A.M. on May 18, Mount St. Helens was shaken by a magnitude 5 earthquake, centred 1 to 2 kilometres beneath its north flank. Geologists Keith and Dorothy Stoffel, who were flying in a light plane about 400 metres above the summit at just that moment, saw several icefalls start down the steep crater walls. About fifteen seconds later they were the closest witnesses to the onset of the largest landslide in recorded history, closely followed by a huge volcanic eruption. The whole north side of the summit crater began to move instantaneously as one gigantic mass, Dorothy recalled. Seconds later a massive explosion shook the mountain. Source Volcanoes - Decker 1998: W.H. Freeman and Co. Table 1 kilometres South 1979 profile Feature X (500m by 300m, by 200m deep) Post-eruption profile North 12th May 1980 profile (bulge - 150m, swelling by 1m per day) Sea Level -1 high Typical seismogram -2 Key pre-eruption eathquake foci amplitude high 15 secs kilometres Figure 1 Source-adapted from Volcanoes - Decker 1998: W.H. Freeman and Co.

3 3 Examiner Refer to Table 1 and Figure 1. (a) Give a name for Feature X on Figure 1 (12 th May profile) and explain its origin. [2] Feature X... Origin... (b) Explain how the distribution and type of seismic activity in Figure 1 might indicate a possible volcanic eruption. [3] (c) (i) Suggest two factors most likely to have been responsible for triggering the landslide. [2] Factor... Factor... (ii) Using all the data provided, account for the shape of the post-eruption profile. [3] (d) Explain the use of one technique by which ground deformation of the northern bulge might have been monitored. [2] Total 12 marks Turn over.

4 4 Examiner 2. Figure 2a shows ground subsidence in the Santa Clara valley, California, together with changes in water table levels caused by groundwater extraction. water table level 0 surface ground subsidence (m) ground subsidence depth of water table (m) time Figure 2a Source: Waltham T. (2002) Foundations of Engineering Geology (2nd edition) Spon Press; London (a) What is meant by the term water table? [1]... (b) Refer to Figure 2a. (i) Calculate the average rate of ground subsidence (mm/year) for the 10 year period between Show your working. [2] Average rate of subsidence... mm/year (ii) Compare the variation in rates of subsidence from with that for [3]

5 (c) 5 Examiner With reference to Figure 2a, describe the relationship between changes in water table levels and ground subsidence. Explain your answer. [4] (d) Mexico City has also subsided as a result of groundwater extraction. Figure 2b shows how buildings of different size, shape and foundation design in Mexico City have subsided by different amounts compared with street level. Water extraction from sand also results in loss of water from clays (dewatering) building on raft foundation has subsided 3 metres more than street level A dewatered clay B basements building on piles subsided at same rate as streets. original street level current street level streets have subsided 1m more than building on deep piles C sand dewatered clay depth>100m to main aquifer sand Refer to Figure 2b. dewatered clay depths of 30-50m to sand beds aquifer sand Figure 2b sand dewatered clay not to scale Source: Geology Today (Volume 18 Issue 3) May 2002 Blackwell Publishing Give a geological explanation for differences in the amount of subsidence of any one building (A, B or C) compared with the subsidence of the current street level. [3] Chosen building (A, B or C) Total 13 marks Turn over.

6 6 SECTION B Answer one question from this Section on the following pages. You are advised to make use of examples where possible in your answer. EITHER, 3. (a) Describe the difference between the magnitude and intensity of an earthquake and the scales used in their measurement. [10] (b) With reference to one or more case studies, explain the use of two of the following methods used to predict earthquakes: (i) electrical resistivity; (ii) radon gas emissions; (iii) the presence of earthquake lights; (iv) seismic activity. [15] OR, 4. (a) Using one or more diagrams, describe how the excavation of a roadway cutting in an area of dipping sandstone and shale strata might lead to slope instability. [10] (b) Explain how slope instability might be overcome by good engineering practice. [15] OR, 5. (a) Describe, giving reasons, the geological factors that need to be considered in the disposal of highly toxic and/or radioactive waste compared with the disposal of domestic waste. [15] (b) With specific reference to one actual (or potential) landfill or underground site, analyse the suitability of the site for the type of waste disposed. [10]

7 7 Examiner Turn over.

8 8 Examiner

9 9 Examiner Turn over.

10 10 Examiner