This script can be used to add shake to a camera in Unity. This is useful for explosions or erratic movements of the camera that can either be sustained or short.

Camera Shake

using UnityEngine;
using System.Collections;

public class Shake : MonoBehaviour
{

	public float shakeDuration = 0f;	
	public float shakeAmount = 0.7f;
	public float decreaseFactor = 1.0f;
	public bool soloStart;
	private float resetDuration; 
	private Transform camTransform;
	
	Vector3 originalPos;
	
	void Awake()
	{		
		camTransform = GetComponent<Transform>();	
	}
	

	void Start ()
	{
		originalPos = camTransform.localPosition;
		resetDuration = shakeDuration;
	
		if(soloStart){
			StartCoroutine("ExplosionShake");
		}
	}

	public void StartExplosionShake ()
	{
		StartCoroutine("ExplosionShake");
	}

	IEnumerator ExplosionShake ()
	{
		 while (shakeDuration > 0)
		{
			camTransform.localPosition = originalPos + Random.insideUnitSphere * shakeAmount;			
			shakeDuration -= Time.deltaTime * decreaseFactor;
			yield return new WaitForEndOfFrame();
		}
			shakeDuration = resetDuration;
			camTransform.localPosition = originalPos;
	}

	
}