Lecture 20

That was the year* that Lisbon townSaw the earth opened up and gulp her down.

(*1755)

- Oliver Wendell Holmes (The Deacon’s Masterpiece)

Earthquakes

Webpage for course (daytime)

Webpage for course (nighttime)

2nd test scores

125 (2)

123 (2)

122

121

120

118

113

112 (2)

110

109

108

107

106 (2)

103

101

100

95 (2)

93

91

88 (2)

84

82

81

80

74

67

64

Seismology – the study of earthquakes

Seismometer

Seismograph

Seismogram

Fig. 14.7, p. 325

Ripple analogy

Three basic types of waves:

Longitudinal (compressive, Primary, P-wave)

Transverse (shear, secondary, S-wave)

Surface waves

Three basic types of waves:

Longitudinal (compressive, Primary, P-wave)

Sound

Three basic types of waves:

Transverse (shear, secondary, S-wave)

Light, radio, RADAR(electromagnetic waves)

Three basic types of waves:

Surface waves

P- and S-waves:

P-waves travel faster than S-waves

P-waves travel through solids and fluidsS-waves do not travel through fluids

So, three questions:

How do you tell how far away a quake is?How do you tell where a quake is?How do we know the earth’s core is molten?

How do you tell how far away a quake is?

How do you tell where a quake is?

How do we know the earth’s core is molten?

Earthquake measurement

Richter scale

logarithmic

Earthquake measurement

Table 14.2, p. 329

Big earthquakes in human history deaths

Shen-shu, China, 1556, 830,000Tangshan, China, 1976 750,000Lisbon, Portugual, 1755 60,000San Francisco, CA, 1906 (8.3) 700Alaska, 1964 (8.5) 114

The killers are:

collapsefirelandslidestsunami

Safety

Safety

Stay calmGo to under some strong objectIf in open, get away from structures

Before earthquakeBuilding codesZoning lawsGood foundation on bedrockHeavy furniture should be bolted downWater mains compartmentalized