Historic Earthquakes: Tectonic Summary

Magnitude 7.4 HINDU KUSH REGION, AFGHANISTAN
2002 March 03 12:08:19 UTC

TECTONIC SETTING

This subduction zone earthquake occurred near the boundary of the Eurasian and Indian tectonic plates. The two plates are converging towards each other at a rate of about 4.4 cm per year. The earthquake occurred in a subducted part of the Eurasian plate, at a depth of about 200 km. The faulting that produced the earthquake reflects internal deformation of the subducted Eurasian plate rather than slip on the boundary between the Eurasian and Indian plates.

This earthquake occurred in the highly-seismic Hindu Kush region. On average, there are four magnitude 5 or greater earthquakes per year whose epicenters are within 60 km of this event. Earthquake depths in this region range from the surface to depths of 330 km.

Although small near-surface earthquakes have been generated by human activity such as mining and reservoir loading, the depth and magnitude of this event preclude any connection with human activity including the recent bombing.

SHALLOW EARTHQUAKES CAUSE MORE DEATHS AND DAMAGE THAN INTERMEDIATE ONES

According to the latest reports, about 150 people were killed in this earthquake. However, the casualty and damage toll would likely have been much higher if the quake had occurred within 35 km (20 miles) of the Earth's surface. Shallow earthquakes cause more damage than intermediate and deep ones since the energy generated by the shallow events is released closer to buildings and therefore produces stronger shaking than by quakes that are deeper within the Earth.

On February 4, 1998, a magnitude 5.9 shallow earthquake struck 70 km (45 miles) northwest of the March 3 quake. That earthquake killed at least 2,323 people, injured 818 and destroyed 8,094 houses in the Rostaq area of Afghanistan. A magnitude 6.6 earthquake, also shallow, hit the same area on May 30, 1998, and killed at least 4,000 people and destroyed many homes in Badakhshan and Takhar Provinces.

By comparison, on February 20, 1998, a magnitude 6.4 earthquake occurred about 60 km (35 miles) east of the March 3, 2002 earthquake, at a depth of about 235 km (145 miles) below the surface. That earthquake killed only one person and destroyed 35 houses in northern Pakistan.

Shallow-depth earthquakes:
1998 Feb 04 14:33:21 37.075N 70.089E  33 km 5.9M  at least 2,323 killed
1998 May 30 06:22:28 37.106N 70.110E  33 km 6.6M  at least 4,000 killed

Intermediate-depth earthquakes:
1998 Feb 20 12:18:06 36.479N 71.076E 236 km 6.4M  1 person killed
2002 Mar 04 12:08:22 36.533N 70.100E 256 km 7.3M  about 150 killed