Originally posted by randomname
to put it in perspective, an earthquake in toronto is about as common as snow in death valley during summer.
Recent earthquakes in Ontario and Quebec:
- June 23, 2010 — 5.0 magnitude quake. Epicentre was 61 km north of Ottawa.
- Feb. 24, 2006 — 4.5 magnitude quake. Epicentre was seven kilometres north of Thurso, Que.
- Jan. 1, 2000 — 5.2 magnitude quake. Epicentre was 70 km northeast of North Bay.
- Oct. 19, 1990 — 5.0 magnitude quake. Epicentre was nine km southwest of Mont-Laurier, Que.
- Dec. 25, 1989 — 5.9 magnitude quake in northern Quebec.
- Nov. 1, 1935 — 6.2 magnitude quake. Epicentre was about 10 km east of Temiscaming, Que.
If the Indo-Australian Plate is not only tilting up on its eastern side but also tipping sideways to raise the curve just under Java and Sumatra, what would this do to relieve pressure in the small platelets just above New Guinea? Here three great plates meet, so the little platelets are fragments very much susceptible to changes in any arrangement the larger plates make. The tipping of the Indo-Australia Plate has allowed this platelet to drop where before it was under pressure from the Pacific, and snagged at the edges, thus lifted with the Indo-Australian Plate.
I'm not sure where liquefaction plays into this scenario, though.
The powerful earthquake produced earthquake liquefaction in the region. Ground fissures and failures caused major structural damage in several communities, much damage to property and several landslides. Anchorage sustained great destruction or damage to many inadequately engineered houses, buildings, and infrastructure (paved streets, sidewalks, water and sewer mains, electrical systems, and other man-made equipment), particularly in the several landslide zones along Knik Arm. Two hundred miles southwest, some areas near Kodiak were permanently raised by 30 feet (9.1 m). Southeast of Anchorage, areas around the head of Turnagain Arm near Girdwood and Portage dropped as much as 8 feet (2.4 m), requiring reconstruction and fill to raise the Seward Highway above the new high tide mark.
I read somewhere a while back in a thread about an eastern US quake that the damage was greater than in the West due to geology differences, but I hadn't considered the effect liquefaction has on that damage until now. It makes a lot of sense
The story begins with an account of how geologists in the mid-1960s came to understand that the "Kiowa fault" in the state of Colorado was actually part of a larger fault system running along the eastern edge of the Rocky Mountains from Texas to the Canadian border. In the summer of 1973 the land east of the fault slips downward, slowly but inexorably over the next few months, until the major rivers of the region (including the Mississippi) flood the new lowlands. The process is slow enough for people to flee eastwards, though conditions become more and more hazardous as the flooding increases. The story recounts how, during this time the various authorities such as the Federal government and the State governors, try to quell panic by invoking patriotism or, in the case of the governors, the stalwart nature of the people of the "great Southland". However the next act of nature proves even more cataclysmic. The Gulf coast of the United States, from western Florida to Lake Ponchartrain, simply sinks below sea level. The sea floods the new lowlands from the Texas Panhandle to North Dakota. As many as 14 million people perish. The state of Oklahoma is completely lost, as are most of the Dakotas, Kansas, Nebraska, and Arkansas. The Ozarks become an archipelago.