17:
253:
120:-bar instruments in tunnels and borehole strainmeters, with a few laser instruments. Starting in 2003 there has been a major effort (the Plate Boundary Observatory) to install many more strainmeters along the Pacific/North-America plate boundary in the
36:
of the Earth. Linear strainmeters measure the changes in the distance between two points, using either a solid piece of material (over a short distance) or a
323:
58:
to measure small changes in the diameter of the borehole. Another type of borehole instrument detects changes in a volume filled with fluid (such as
234:
294:
54:. Modern instruments of this type can make measurements of length changes over very small distances, and are commonly placed in
81:
to periods of days, months, and years. This allows them to measure signals at lower frequencies than can be detected with
66:
invented by Sacks and
Evertson in the USA (patent 3,635,076); a design that uses specially shaped volumes to measure the
318:
16:
287:
164:
219:
328:
74:
33:
280:
149:
179:
154:
228:
8:
313:
125:
268:
188:
98:
238:
223:
102:
264:
40:
307:
121:
67:
192:
159:
90:
82:
29:
63:
260:
137:
133:
106:
94:
86:
50:
in 1932, using an iron pipe; later instruments used rods made of fused
124:. The aim is to install about 100 borehole strainmeters, primarily in
97:. At longer periods, they can also record the gradual accumulation of
55:
211:
59:
47:
129:
117:
51:
206:
113:
78:
37:
216:
112:
The most extensive network of strainmeters is installed in
46:
The type using a solid length standard was invented by
252:
43:(over a long distance, up to several hundred meters).
109:, and rapid changes of stress following earthquakes.
85:. Most strainmeter records show signals from the
305:
177:Agnew DC (1986). "Strainmeters and tiltmeters".
207:Piñon Flat Observatory, CA: laser strainmeters
288:
212:GTSM Technologies, AUS: borehole strainmeters
324:Length, distance, or range measuring devices
73:All these types of strainmeters can measure
295:
281:
176:
15:
70:has been developed by Sakata in Japan.
306:
136:, and five laser strainmeters, all in
247:
13:
62:oil). The most common type is the
14:
340:
200:
251:
229:US Geological Survey, see under
105:, the release of this stress in
1:
170:
267:. You can help Knowledge by
77:over frequencies from a few
7:
165:Infinitesimal strain theory
143:
10:
345:
246:
217:Plate Boundary Observatory
28:is an instrument used by
193:10.1029/RG024i003p00579
319:Seismology instruments
263:-related article is a
150:Deformation monitoring
21:
20:Distortion seismometer
180:Reviews of Geophysics
155:Deformation (physics)
116:; it includes mostly
19:
237:2010-04-12 at the
222:2009-11-24 at the
22:
276:
275:
336:
329:Geophysics stubs
297:
290:
283:
255:
248:
231:Fault Monitoring
196:
99:stress (physics)
344:
343:
339:
338:
337:
335:
334:
333:
304:
303:
302:
301:
244:
239:Wayback Machine
224:Wayback Machine
203:
173:
146:
103:plate tectonics
32:to measure the
12:
11:
5:
342:
332:
331:
326:
321:
316:
300:
299:
292:
285:
277:
274:
273:
256:
242:
241:
226:
214:
209:
202:
201:External links
199:
198:
197:
187:(3): 579–624.
172:
169:
168:
167:
162:
157:
152:
145:
142:
41:interferometer
9:
6:
4:
3:
2:
341:
330:
327:
325:
322:
320:
317:
315:
312:
311:
309:
298:
293:
291:
286:
284:
279:
278:
272:
270:
266:
262:
257:
254:
250:
249:
245:
240:
236:
233:
232:
227:
225:
221:
218:
215:
213:
210:
208:
205:
204:
194:
190:
186:
182:
181:
175:
174:
166:
163:
161:
158:
156:
153:
151:
148:
147:
141:
139:
135:
131:
127:
123:
122:United States
119:
115:
110:
108:
104:
100:
96:
92:
91:seismic waves
88:
84:
80:
76:
71:
69:
68:strain tensor
65:
61:
57:
53:
49:
44:
42:
39:
35:
31:
30:geophysicists
27:
18:
269:expanding it
258:
243:
230:
184:
178:
160:Extensometer
111:
83:seismometers
72:
45:
25:
23:
107:earthquakes
95:earthquakes
87:earth tides
75:deformation
64:dilatometer
34:deformation
26:strainmeter
314:Geophysics
308:Categories
261:geophysics
171:References
138:California
134:California
126:Washington
101:caused by
56:boreholes
235:Archived
220:Archived
144:See also
60:silicone
48:Benioff
130:Oregon
118:quartz
89:, and
52:quartz
259:This
114:Japan
93:from
38:laser
265:stub
132:and
189:doi
310::
185:24
183:.
140:.
128:,
79:Hz
24:A
296:e
289:t
282:v
271:.
195:.
191::
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
